Mark Reynolds

Publications

Refereed

48) Deep Chandra Observations of the Compact Starburst Galaxy Henize 2-10: X-rays from the Massive Black Hole
Amy Reines, Mark Reynolds, Jon Miller, Gregory Sivakoff, Jenny Grenne, Ryan Hickox, Kelsey Johnson, 2016, ApJL, in press: We present follow-up X-ray observations of the candidate massive black hole (BH) in the nucleus of the low-mass, compact starburst galaxy Henize 2-10. Using new high-resolution observations from the Chandra X-ray Observatory totaling 200 ks in duration, as well as archival Chandra observations from 2001, we demonstrate the presence of a previously unidentified X-ray point source that is spatially coincident with the known nuclear radio source in Henize 2-10 (i.e., the massive BH). We show that the hard X-ray emission previously identified in the 2001 observation is dominated by a source that is distinct from the nucleus, with the properties expected for a high-mass X-ray binary. The X-ray luminosity of the nuclear source suggests the massive BH is radiating significantly below its Eddington limit (~1e-6 L_Edd), and the soft spectrum resembles other weakly accreting massive BHs including Sagittarius A*. Analysis of the X-ray light curve of the nucleus reveals the tentative detection of a ~9-hour periodicity, although additional observations are required to confirm this result. Our study highlights the need for sensitive high-resolution X-ray observations to probe low-level accretion, which is the dominant mode of BH activity throughout the Universe.
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47) A cold neutron star in the transient low-mass X-ray binary HETE J1900.1-2455 after 10 years of active accretion
Nathalie Degenaar, Laura Ootes, Mark Reynolds, Rudy Wijnands, Dany Page, 2016, MNRAS, in press: The neutron star low-mass X-ray binary and intermittent millisecond X-ray pulsar HETE J1900.1-2455 returned to quiescence in late 2015, after a prolonged accretion outburst of ~10 yr. Using a Chandra observation taken ~180 d into quiescence we detect the source at a luminosity of ~4.5E31 (D/4.7 kpc)^2 erg/s (0.5-10 keV). The X-ray spectrum can be described by a neutron star atmosphere model with a temperature of ~54 eV for an observer at infinity. We perform thermal evolution calculations based on the 2016 quiescent data and a <98 eV temperature upper limit inferred from a Swift observation taken during an unusually brief (<2 weeks) quiescent episode in 2007. We find no evidence in the present data that the thermal properties of the crust, such as the heating rate and thermal conductivity, are different than those of non-pulsating neutron stars. Finding this neutron star so cold after its long outburst imposes interesting constraints on the heat capacity of the stellar core; these become even stronger if further cooling were to occur.
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46) The Intermediate Luminosity Optical Transient SN 2010da: The Progenitor, Eruption, and Aftermath of a Peculiar Supergiant High-mass X-Ray Binary
Ashley Villar, Edo Berger, Ryan Chornock, Rafaella Margutti, Tanmoy Laskar, Peter Brown, Peter Blanchard, Ian Czekala, Ragnhild Lunnan, Mark Reynolds, 2016, ApJ, 830, 37: We present optical spectroscopy, ultraviolet-to-infrared imaging, and X-ray observations of the intermediate luminosity optical transient (ILOT) SN 2010da in NGC 300 (d = 1.86 Mpc) spanning from ‑6 to +6 years relative to the time of outburst in 2010. Based on the light-curve and multi-epoch spectral energy distributions of SN 2010da, we conclude that the progenitor of SN 2010da is a ≈10–12 M ⊙ yellow supergiant possibly transitioning into a blue-loop phase. During outburst, SN 2010da had a peak absolute magnitude of M bol ≲ ‑10.4 mag, dimmer than other ILOTs and supernova impostors. We detect multi-component hydrogen Balmer, Paschen, and Ca ii emission lines in our high-resolution spectra, which indicate a dusty and complex circumstellar environment. Since the 2010 eruption, the star has brightened by a factor of ≈5 and remains highly variable in the optical. Furthermore, we detect SN 2010da in archival Swift and Chandra observations as an ultraluminous X-ray source (L_X ≈ 6 × 1e39 erg/s). We additionally attribute He ii 4686 Å and coronal Fe emission lines in addition to a steady X-ray luminosity of ≈1e37 erg/s to the presence of a compact companion.
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45) NuSTAR Observations of the Black Hole GS 1354-645: Evidence of Rapid Black Hole Spin
Adham El-Batal, Jon Miller, Mark Reynolds, Steve Boggs, Finn Chistensen, Will Craig, Felxi Fuerst, Craig Hailey, Fiona Harrison, Daniel Stern, Jon Tomsick, Dominic Walton, Will Zhang, 2016, ApJL, 826, 12: We present the results of a NuSTAR study of the dynamically confirmed stellar-mass black hole GS 1354-645. The source was observed during its 2015 “hard” state outburst; we concentrate on spectra from two relatively bright phases. In the higher-flux observation, the broadband NuSTAR spectra reveal a clear, strong disk reflection spectrum, blurred by a degree that requires a black hole spin of a={cJ}/{{GM}}2≥slant 0.98 (1σ statistical limits only). The fits also require a high inclination: θ ≃ 75{(2)}\circ . Strong “dips” are sometimes observed in the X-ray light curves of sources viewed at such an angle; these are absent, perhaps indicating that dips correspond to flared disk structures that only manifest at higher accretion rates. In the lower flux observation, there is evidence of radial truncation of the thin accretion disk. We discuss these results in the context of spin in stellar-mass black holes, and inner accretion flow geometries at moderate accretion rates.
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44) High-resolution Chandra HETG Spectroscopy of V404 Cygni in Outburst
Ashley King, Jon Miller John Raymond, Mark Reynolds, Warren Morningstar, 2015, ApJL, 813, 37: As one of the best-characterized stellar-mass black holes, with good measurements of its mass, distance, and inclination, V404 Cyg is the ideal candidate to study Eddington-limited accretion episodes. After a long quiescent period, V404 Cyg underwent a new outburst in 2015 June. We obtained two Chandra HETG exposures of 20 and 25 ks. Many strong emission lines are observed; the ratio of Si He-like triplet lines gives an estimate for the formation region distance of 4e11 cm. A narrow Fe K_alpha line is detected with an equivalent width greater than 1 keV in many epochs, signaling that we do not directly observe the central engine. Obscuration of the central engine and strong narrow emission lines signal that the outer disk may be illuminated, and its structure may help to drive the strong variability observed in V404 Cyg. In the highest flux phases, strong P-Cygni profiles consistent with a strong disk wind are observed, likely radiation or thermally driven as V404 Cyg approaches its Eddington limit. The kinetic power of this wind may be extremely high at > 0.1 L_Bol.
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43) Flows of X-ray gas reveal the disruption of a star by a massive black hole
Jon Miller, Jelle Kaastra, Coleman Miller, Mark Reynolds, Gregory Brown, Bradley Cenko, Jeremy Drake, Suvi Gezari, James Guillochon, Kayhan Gultekin, Jimmy Irwin, Andrew Levan, Dipankar Maitra, Peter Makysm, Richard Mushotzky, Paul O'Brien, Frits Paerels, Jelle de Plaa, Enrico Ramirez-Ruiz, Tod Strohmayer, Nial Tanvir, 2015, Natur, 526, 542: Tidal forces close to massive black holes can violently disrupt stars that make a close approach. These extreme events are discovered via bright X-ray and optical/ultraviolet flares in galactic centres. Prior studies based on modelling decaying flux trends have been able to estimate broad properties, such as the mass accretion rate. Here we report the detection of flows of hot, ionized gas in high-resolution X-ray spectra of a nearby tidal disruption event, ASASSN-14li in the galaxy PGC 043234. Variability within the absorption-dominated spectra indicates that the gas is relatively close to the black hole. Narrow linewidths indicate that the gas does not stretch over a large range of radii, giving a low volume filling factor. Modest outflow speeds of a few hundred kilometres per second are observed; these are below the escape speed from the radius set by variability. The gas flow is consistent with a rotating wind from the inner, super-Eddington region of a nascent accretion disk, or with a filament of disrupted stellar gas near to the apocentre of an elliptical orbit. Flows of this sort are predicted by fundamental analytical theory and more recent numerical simulations.
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42) A Dynamical Study of the Black Hole X-ray Binary Nova Muscae 1991
Jianfeng Wu, Jerome Orosz, Jeffrey McClintock, Danny Steeghs, Penelope Longa-Pena, Paul Callanan, Lijon Gou, Luis Ho, Peter Jonker, Mark Reynolds, Manuel Torres, 2015, ApJ, 806, 92: We present a dynamical study of the Galactic black hole binary system Nova Muscae 1991 (GS/GRS 1124-683). We utilize 72 high resolution Magellan Echellette (MagE) spectra and 72 strictly simultaneous V-band photometric observations; the simultaneity is a unique and crucial feature of this dynamical study. The data were taken on two consecutive nights and cover the full 10.4-hour orbital cycle. The radial velocities of the secondary star are determined by cross-correlating the object spectra with the best-match template spectrum obtained using the same instrument configuration. Based on our independent analysis of five orders of the echellette spectrum, the semi-amplitude of the radial velocity of the secondary is measured to be K_2 = 406.8+/-2.2 km/s, which is consistent with previous work, while the uncertainty is reduced by a factor of 3. The corresponding mass function is f(M) = 3.02+/-0.05 M_\odot. We have also obtained an accurate measurement of the rotational broadening of the stellar absorption lines (v sin i = 80.9+/-1.3 km/s) and hence the mass ratio of the system q = 0.070+/-0.003. Finally, we have measured the spectrum of the non-stellar component of emission that veils the spectrum of the secondary. In a future paper, we will use our veiling-corrected spectrum of the secondary and accurate values of K_2 and q to model multi-color light curves and determine the systemic inclination and the mass of the black hole.
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41) Broad Iron Emission from Gravitationally Lensed Quasars Observed by Chandra
Domonic Walton, Mark Reynolds, Jon Miller, Rubens Reis, Daniel Stern, Fiona Harrison, 2015, ApJ, 805, 161: Recent work has demonstrated the potential of gravitationally lensed quasars to extend measurements of black hole spin out to high-redshift with the current generation of X-ray observatories. Here we present an analysis of a large sample of 27 lensed quasars in the redshift range 1.0 < z < 4.5 observed with Chandra, utilizing over 1.6 Ms of total observing time, focusing on the rest-frame iron K emission from these sources. Although the X-ray signal-to-noise (S/N) currently available does not permit the detection of iron emission from the inner accretion disk in individual cases in our sample, we find significant structure in the stacked residuals. In addition to the narrow core, seen almost ubiquitously in local AGN, we find evidence for an additional underlying broad component from the inner accretion disk, with a clear red wing to the emission profile. Based on simulations, we find the detection of this broader component to be significant at greater than the 3-sigma level. This implies that iron emission from the inner disk is relatively common in the population of lensed quasars, and in turn further demonstrates that, with additional observations, this population represents an opportunity to significantly extend the sample of AGN spin measurements out to high-redshift.
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40) Tomography of X-ray Nova Muscae 1991: Evidence for ongoing mass transfer and stream-disc overflow
Charith Peris, Saeqa Vrtilek, James Steiner, Jianfeng Wu, Jeffrey McClintock, Penelope Longa-Pena, Danny Steeghs, Paul Callanan, Luis Ho, Jerome Orosz, Mark Reynolds, 2015, MNRAS, 449, 1584: We present a spectroscopic analysis of the black hole binary Nova Muscae 1991 in quiescence using data obtained in 2009 with MagE on the Magellan Clay telescope and in 2010 with IMACS on the Magellan Baade telescope at the Las Campanas Observatory. Emission from the disc is observed in H alpha, H beta and Ca II (8662 A). A prominent hotspot is observed in the Doppler maps of all three emission lines. The existence of this spot establishes ongoing mass transfer from the donor star in 2009-2010 and, given its absence in the 1993-1995 observations, demonstrates the presence of a variable hotspot in the system. We find the radial distance to the hotspot from the black hole to be consistent with the circularization radius. Our tomograms are suggestive of stream-disc overflow in the system. We also detect possible Ca II (8662 A) absorption from the donor star.
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39) Are spectral and timing correlations similar in different spectral states in black hole X-ray binaries?
Maithili Kalamkar, Mark Reynolds, Michel van der Klis, Diego Altamirano, Jon Miller, 2015, ApJ, 802, 32: We study the outbursts of the black hole X-ray binaries MAXI J1659-152, SWIFT J1753.5--0127 and GX 339-4 with the Swift X-ray Telescope. The bandpass of the X-ray Telescope has access to emission from both components of the accretion flow: the accretion disk and the corona/hot flow. This allows a correlated spectral and variability study, with variability from both components of the accretion flow. We present for the first time, a combined study of the evolution of spectral parameters (disk temperature and radius) and timing parameters (frequency and strength) of all power spectral components in different spectral states. Comparison of the correlations in different spectral states shows that the frequency and strength of the power spectral components exhibit dependencies on the disk temperature that are different in the (low-)hard and the hard-intermediate states; most of these correlations that are clearly observed in the hard-intermediate state (in MAXI J1659-152 and GX 339-4) are not seen in the (low-)hard state (in GX 339-4 and SWIFT J1753.5-0127). Also, the responses of the individual frequency components to changes in the disk temperature are markedly different from one component to the next. Hence, the spectral-timing evolution cannot be explained by a single correlation that spans both these spectral states. We discuss our findings in the context of the existing models proposed to explain the origin of variability.
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38) The Rate of Gas Accretion onto Black Holes Drives Jet Velocity
Ashley King, Jon Miller, Micheal Bietenholz, Kayhan Gultekin, Mark Reynolds, Amy Mioduszewski, Micheal Rupen, Norbert Bartel 2015, ApJL, 799, 8: Accreting black holes are observed to launch relativistic, collimated jets of matter and radiation. In some sources, discrete ejections have been detected with highly relativistic velocities. These particular sources typically have very high mass accretion rates, while sources lower knot velocities are predominantly associated with black holes with relatively low mass accretion rates. We quantify this behavior by examining knot velocity with respect to X-ray luminosity, a proxy for mass accretion rate onto the black hole. We find a positive correlation between the mass-scaled X-ray luminosity and jet knot velocity. In addition, we find evidence that the jet velocity is also a function of polar angle, supporting the "spine-sheath" model of jet production. Our results reveal a fundamental aspect of how accretion shapes mechanical feedback from black holes into their host environments.
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37) Swift Monitoring of 4U 1957+11: Constraints on Binary Parameters and Nature of the Accretor
Dipankar Maitra, Jon Miller, Mark Reynolds, Rubens Reis, Mike Nowak 2014, ApJ, 794, 85: We present new results of uniform spectral analysis of Swift/XRT observations of the X-ray binary system 4U 1957+11. This includes 26 observations of the source made between MJD 54282-55890 (2007 July 01 - 2011 November 25). All 26 spectra are predominantly thermal, and can be modeled well with emission from an accretion disk around a black hole. We analyze all 26 spectra jointly using traditional chi-squared fitting as well as Markov Chain Monte Carlo simulations. The results from both methods agree, and constrains on model parameters like inclination, column density, and black hole spin. These results indicate that the X-ray emitting inner accretion disk is inclined to our line-of-sight by 77.6^{+1.5}_{-2.2} degrees. Additionally, the other constraints we obtain on parameters like the column density and black hole spin are consistent with previous X-ray observations. Distances less than 5 kpc are unlikely and not only ruled out based on our analysis but also from other independent observations. Based on model-derived bolometric luminosities, we require the source distance to be >10 kpc if the black hole's mass is >10 M_Sun. If the hole's mass is <10 M$_{Sun}$, then the distance could be in the range of 5-10 kpc.
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36) A Rapidly Spinning Black Hole Powers the Einstein Cross
Mark Reynolds, Dominic Walton, Jon Miller, Rubens Reis, 2014, ApJL, 792, 19: Observations over the past 20 years have revealed a strong relationship between the properties of the supermassive black hole (SMBH) lying at the center of a galaxy and the host galaxy itself. The magnitude of the spin of the black hole will play a key role in determining the nature of this relationship. To date, direct estimates of black hole spin have been restricted to the local Universe. Herein, we present the results of an analysis of ~ 0.5 Ms of archival Chandra observations of the gravitationally lensed quasar Q 2237+0305 (aka the "Einstein-cross"), lying at a redshift of z = 1.695. The boost in flux provided by the gravitational lens allows constraints to be placed on the spin of a black hole at such high redshift for the first time. Utilizing state of the art relativistic disk reflection models, the black hole is found to have a spin of a_* = 0.74^{+0.06}_{-0.03} at the 90% confidence level. Placing a lower limit on the spin, we find a_* > 0.65 (4σ). The high value of the spin for the ~ 10^9 M_sun black hole in Q 2237+0305 lends further support to the coherent accretion scenario for black hole growth. This is the most distant black hole for which the spin has been directly constrained to date.
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35) The peculiar Galactic center neutron star X-ray binary XMM J174457-2850.3
Nathalie Degenaar, Rudy Wijnands, Mark Reynolds, Jon Miller, Diego Altamirano, Jamie Kennea, Neil Gehrels, Daryl Haggard, Gabriele Ponti, 2014, ApJ, 792, 109: The recent discovery of a milli-second radio pulsar experiencing an accretion outburst similar to those seen in low mass X-ray binaries, has opened up a new opportunity to investigate the evolutionary link between these two different neutron star manifestations. The remarkable X-ray variability and hard X-ray spectrum of this object can potentially serve as a template to search for other X-ray binary/radio pulsar transitional objects. Here we demonstrate that the transient X-ray source XMM J174457-2850.3 near the Galactic center displays similar X-ray properties. We report on the detection of an energetic thermonuclear burst with an estimated duration of ~2 hr and a radiated energy output of ~5E40 erg, which unambiguously demonstrates that the source harbors an accreting neutron star. It has a quiescent X-ray luminosity of Lx~5E32 erg/s and exhibits occasional accretion outbursts during which it brightens to Lx~1E35-1E36 erg/s for a few weeks (2-10 keV). However, the source often lingers in between outburst and quiescence at Lx~1E33-1E34 erg/s. This unusual X-ray flux behavior and its relatively hard X-ray spectrum, a power law with an index of ~1.4, could possibly be explained in terms of the interaction between the accretion flow and the magnetic field of the neutron star.
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34) The quiescent X-ray spectrum of accreting black holes
Mark Reynolds, Rubens Reis, Jon Miller, Edward Cackett, Nathalie Degenaar, 2014, MNRAS, 441, 3656: The quiescent state is the dominant accretion mode for black holes on all mass scales. Our knowledge of the X-ray spectrum is limited due to the characteristic low luminosity in this state. Herein, we present an analysis of the sample of dynamically-confirmed stellar-mass black holes observed in quiescence in the \textit{Chandra/XMM-Newton/Suzaku} era resulting in a sample of 8 black holes with $\sim$ 570 ks of observations. In contrast to the majority of AGN where observations are limited by contamination from diffuse gas, the stellar-mass systems allow for a clean study of the X-ray spectrum resulting from the accretion flow alone. The data are characterized using simple models. We find a model consisting of a power-law or thermal bremsstrahlung to both provide excellent descriptions of the data, where we measure Γ = 2.06 +/- 0.03 and kT = 5.03^{+0.33}_{-0.31} keV respectively in the 0.3 -- 10 keV bandpass, at a median luminosity of L_x ~ 5.5e-7 L_{Edd}. This result in discussed in the context of our understanding of the accretion flow onto stellar and supermassive black holes at low luminosities.
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33) The 2013 outburst of a transient very faint X-ray binary, 23'' from Sgr A*
Eric Koch, Arash Bahramian, Craig Heinke, Kaya Mori, Nanda Rea, Nathalie Degenaar, Daryl Haggard, Rudi Wijnands, Gabriele Ponti, Jon Miller, Farhad Yusef-Zadeh, Francois Dufour, William Cotton, Fred Baganoff, Mark Reynolds, 2014, MNRAS, 442, 372: We report observations using the Swift/XRT, NuSTAR, and Chandra X-ray telescopes of the transient X-ray source CXOGC J174540.0-290005, during its 2013 outburst. Due to its location in the field of multiple observing campaigns targeting Sgr A*, this is one of the best-studied outbursts of a very faint X-ray binary (VFXB; peak L_x < 1e36 erg/s) yet recorded, with detections in 173 ks of X-ray observations over 50 days. VFXBs are of particular interest, due to their unusually low outburst luminosities and time-averaged mass transfer rates, which are hard to explain within standard accretion physics and binary evolution. The 2013 outburst of CXOGC J174540.0-290005 peaked at L_x(2-10 keV)=$5.0e35 erg/s, and all data above 1e34 ergs/s were well-fit by an absorbed power-law of photon index ~1.7, extending from 2 keV out to ~70 keV. We discuss the implications of these observations for the accretion state of CXOGC J174540.0-290005.
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32) Chandra Spectroscopy of MAXI J1305-704: Detection of an Infalling Black Hole Disk Wind?
Jon Miller, John Raymond, Tim Kallman, Dipankar Maitra, Andy Fabian, Daniel Proga, Chris Reynolds, Mark Reynolds, Nathalie Degenaar, Ed Cackett, Jamie Kennea, Andrew Beardmore 2014, ApJ, 788, 53: We report on a Chandra/HETG X-ray spectrum of the transient X-ray binary MAXI J1305-704. A rich absorption complex is detected in the Fe L band, including density-sensitive lines from Fe XX, XXI, and XXII. Spectral analysis over three wavelength bands with a large grid of XSTAR photoionization models generally requires a gas density of n > 1 E+17 cm^-3. Assuming a luminosity of L = 1 E+37 erg/s, fits to the 10-14 Angstrom band constrain the absorbing gas to lie within r = 3.9 +/- 0.7 E+3 km from the central engine, or about r = 520 +/- 90 (M/5 Msun) r_g, where r_g = GM/c^2. At this small distance from the compact object, gas in stable orbits should have a gravitational red-shift of z = v/c = 3 +/- 1 E-3 (M/5 Msun), and any tenuous inflowing gas should have a free-fall velocity of v/c = 6 +/- 1 E-2 (M/5 Msun)^(1/2). The best-fit single-zone photoionization models measure a red-shift of v/c = 2.6-3.2 E-3. Models with two absorbing zones provide significantly improved fits, and the additional zone is measured to have a red-shift of v/c =4.6-4.9 E-2. Thus, the observed shifts are broadly consistent with those expected at the photoionization radius. The absorption spectrum revealed in MAXI J1305-704 may be best explained in terms of a "failed wind" like those predicted in some recent numerical simulations of black hole accretion flows. The robustness of the velocity shifts was explored through detailed simulations with the Chandra/MARX ray-tracing package, and analysis of the zeroth-order ACIS-S3 spectrum. The simulations and ACIS spectrum suggest that the shifts are not instrumental; however, strong caution is warranted. We discuss our results in the context of accretion flows in stellar-mass black holes and active galactic nuclei, and the potential role of failed winds in emerging connections between disk outflows and black hole state transitions.
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31) Multi-wavelength Coverage of State Transitions in the New Black Hole X-Ray Binary Swift J1910.2-0546
Nathalie Degenaar, Dipankar Maitra, Edward Cackett, Mark Reynolds, Jon Miller, Rubens Reis, Ashley King, Kayhan Gultekin, Charles Bailyn, Michelle Buxton, Racheal MacDonald, Andrew Fabian, Derek Fox, Eli Rykoff, 2014, ApJ, 784, 122: Understanding how black holes accrete and supply feedback to their environment is one of the outstanding challenges of modern astrophysics. Swift J1910.2-0546 is a candidate black hole low-mass X-ray binary that was discovered in 2012 when it entered an accretion outburst. To investigate the binary configuration and the accretion morphology, we monitored the evolution of the outburst for sime3 months at X-ray, UV, optical (B, V, R, I), and near-infrared (J, H, K) wavelengths using Swift and SMARTS. The source evolved from a hard to a soft X-ray spectral state with a relatively cold accretion disk that peaked at sime0.5 keV. A Chandra/HETG spectrum obtained during this soft state did not reveal signatures of an ionized disk wind. Both the low disk temperature and the absence of a detectable wind could indicate that the system is viewed at relatively low inclination. The multi-wavelength light curves revealed two notable features that appear to be related to X-ray state changes. First, a prominent flux decrease was observed in all wavebands ~= 1-2 weeks before the source entered the soft state. This dip occurred in (0.6-10 keV) X-rays ~= 6 days later than at longer wavelengths, which could possibly reflect the viscous timescale of the disk. Second, about two weeks after the source transitioned back into the hard state, the UV emission significantly increased while the X-rays steadily decayed. We discuss how these observations may reflect changes in the accretion morphology, perhaps related to the quenching/launch of a jet or the collapse/recovery of a hot flow.
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30) Reflection From the Strong Gravity Regime in a z=0.658 Gravitationally Lensed-Quasar
Rubens Reis, Mark Reynolds, Jon Miller, Dominic Walton, 2014, Nature, 507, 207: The co-evolution of a supermassive black hole with its host galaxy through cosmic time is encoded in its spin. At $z>2$, supermassive black holes are thought to grow mostly by merger-driven accretion leading to high spin. However, it is unknown whether below $z\sim1$ these black holes continue to grow via coherent accretion or in a chaotic manner, though clear differences are predicted in their spin evolution. An established method to measure the spin of black holes is via the study of relativistic reflection features from the inner accretion disk. Owing to their greater distances, there has hitherto been no significant detection of relativistic reflection features in a moderate-redshift quasar. Here, we use archival data together with a new, deep observation of a gravitationally-lensed quasar at $z=0.658$ to rigorously detect and study reflection in this moderate-redshift quasar. The level of relativistic distortion present in this reflection spectrum enables us to constrain the emission to originate within $\lesssim3$ gravitational radii from the black hole, implying a spin parameter $a=0.87^{+0.08}_{-0.15} $ at the $3\sigma$ level of confidence and $a>0.66$ at the $5\sigma$ level. The high spin found here is indicative of growth via coherent accretion for this black hole, and suggests that black hole growth between $0.5\lesssim z \lesssim 1$ occurs principally by coherent rather than chaotic accretion episodes.
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29) A Seyfert-2-like Spectrum in the High-Mass X-ray Binary Microquasar V4641 Sgr
Warren Morningstar, Jon Miller, Mark Reynolds, Dipankar Maitra, 2014, ApJL, 786, 20: We present an analysis of three archival Chandra observations of the black hole V4641 Sgr, performed during a decline into quiescence. The last two observations in the sequence can be modeled with a simple power-law. The first spectrum, however, is remarkably similar to spectra observed in Seyfert-2 active galactic nuclei, which arise through a combination of obscuration and reflection from distant material. This spectrum of V4641 Sgr can be fit extremely well with a model including partial-covering absorption and distant reflection. This model recovers a Gamma = 2 power-law incident spectrum, typical of black holes at low Eddington fractions. The implied geometry is plausible in a high-mass X-ray binary like V4641 Sgr, and may be as compelling as explanations invoking Doppler-split line pairs in a jet, and/or unusual Comptonization. We discuss potential implications and means of testing these models.
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28) SWIFT J1910.2-0546: A possible black hole binary with a retrograde spin or truncated disk
Rubens Reis, Mark Reynolds, Jon Miller, Dominic Walton, Dipankar Maitra, Ashley King, Nathalie Degenaar, 2013, ApJ, 778, 155: We present the first results from a long (51 ks) XMM-Newton observation of the Galactic X-ray binary Swift J1910.2-0546 in a intermediate state, obtained during its 2012 outburst. A clear, asymmetric iron emission line is observed and physically motivated models are used to fully describe the emission-line profile. Unlike other sources in their intermediate spectral states, the inner accretion disk in Swift J1910.2-0546 appears to be truncated, with an inner radius of \rin$=9.4^{+1.7}_{-1.3}$\rg\ at a 90% confidence limit. Quasi-periodic oscillations are also found at approximately 4.5 and 6 hz, which correlates well with the break frequency of the underlying broad-band noise. Assuming that the line emission traces the ISCO, as would generally be expected for an intermediate state, the current observation of Swift J1910.2-0546 may offer the best evidence for a possible retrograde stellar mass black hole with a spin parameter $a< -0.32 cJ/GM^2$ (90% confidence). Although this is an intriguing possibility, there are also a number of alternative scenarios which do not require a retrograde spin. For example, the inner accretion disk may be truncated at an unusually high luminosity in this case, potentially suffering frequent evaporation/condensation, or it could instead be persistently evacuated through mass loss in a relativistic jet. Further observations are required to distinguish between these different interpretations.
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27) RATS-Kepler -- a deep high cadence survey of the Kepler field
Gavin Ramsay, Adam Brooks, Pasi Hakala, Thomas Barclay, David Garcia-Alvarez, Victoria Antoci, Sandra Greiss, Martin Still, Danny Steeghs, Boris Gansicke, Mark Reynolds, 2014, MNRAS, 437, 132: We outline the purpose, strategy and first results of a deep, high cadence, photometric survey of the Kepler field using the Isaac Newton Telescope on La Palma and the MDM 1.3m Telescope on Kitt Peak. Our goal was to identify sources located in the Kepler field of view which are variable on a timescale of a few mins to 1 hour. The astrophysically most interesting sources would then have been candidates for observation using Kepler using 1 min sampling. Our survey covered ~42% of the Kepler field of view and we have obtained light curves for 7.1x10^5 objects in the range 13< g <20. We have discovered more than 100 variable sources which have passed our two stage identification process. As a service to the wider community, we make our data products and cleaned CCD images available to download. We obtained Kepler data of 18 sources which we found to be variable using our survey and we give an overview of the currently available data here. These sources include a pulsating DA white dwarf, eleven delta Sct stars which have dominant pulsation periods in the range 24 min to 2.35 hrs, three contact binaries, and a cataclysmic variable (V363 Lyr). One of the delta Sct stars is in a contact binary.
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26) Revisiting Putative Cool Accretion Disks in Ultraluminous X-ray Sources
Jon Miller, Dominic Walton, Ashley King, Mark Reynolds, Andy Fabian, Cole Miller, Rubens Reis, 2013, ApJ, 776, 36: Soft, potentially thermal spectral components observed in some ULXs can be fit with models for emission from cool, optically-thick accretion disks. If that description is correct, the low temperatures that are observed imply accretion onto "intermediate-mass" black holes. Subsequent work has found that these components may follow an inverse relationship between luminosity and temperature, implying a non-blackbody origin for this emission. We have re-analyzed numerous XMM-Newton spectra of extreme ULXs. Crucially, observations wherein the source fell on a chip gap were excluded owing to their uncertain flux calibration, and the neutral column density along the line of sight to a given source was jointly determined by multiple spectra. The luminosity of the soft component is found to be positively correlated with temperature, and to be broadly consistent with L ~ T^4 in the measured band pass, as per blackbody emission from a standard thin disk. These results are nominally consistent with accretion onto black holes with masses above the range currently known in Galactic X-ray binaries, though there are important caveats. Emission from inhomogeneous or super-Eddington disks may also be consistent with the data.
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25) An X-ray-UV correlation in Cen X-4 during quiescence
Edward Cackett, Edward Brown, Nathalie Degenaar, Jon Miller Mark Reynolds, Rudy Wijnands, 2013, MNRAS, 433, 1362: Quiescent emission from the neutron star low-mass X-ray binary Cen X-4 is seen to be variable on timescales from hundreds of seconds to years, suggesting that at least in this object, low-level accretion is important during quiescence. Here we present results from recent XMM-Newton and Swift observations of Cen X-4, where the X-ray flux (0.5 - 10 keV) varies by a factor of 6.5 between the brightest and faintest states. We find a positive correlation between the X-ray flux and the simultaneous near-UV flux, where as there is no significant correlation between the X-ray and simultaneous optical (V, B) fluxes. This suggests that while the X-ray and UV emitting regions are somehow linked, the optical region originates elsewhere. Comparing the luminosities, it is plausible that the UV emission originates due to reprocessing of the X-ray flux by the accretion disk, with the hot inner region of the disk being a possible location for the UV emitting region. The X-ray/UV correlation does not favour the accretion stream-impact point as the source of the UV emission.
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23) A Distinctive Disk-Jet Coupling in the Lowest-Mass Seyfert, NGC 4395
Ashley King, Jon Miller, Mark Reynolds, Kayhan Gultekin, Elena Gallo, Dipankar Maitra 2013, ApJ, 774, 25: Simultaneous observations of X-rays and radio luminosities have been well studied in accreting stellar-mass black holes. These observations are performed in order to understand how mass accretion rates and jetted outflows are linked in these individual systems. Such contemporaneous studies in supermassive black holes (SMBH) are harder to perform, as viscous times scale linearly with mass. However, as NGC 4395 is the lowest known mass Seyfert galaxy, we have used it to examine the simultaneous X-ray (Swift) and radio (VLA) correlation in a SMBH in a reasonably timed observing campaign. We find that the intrinsic X-ray variability is stronger than the radio variability, and that the fluxes are only weakly or tentatively coupled, similar to prior results obtained in NGC 4051. If the corona and the base of the jet are one and the same, this may suggest that the corona in radio-quiet AGN filters disk variations, only transferring the strongest and/or most sustained variations into the jet. Further, when both NGC 4395 and NGC 4051 are placed on the stellar-mass L_X-L_R plane, they appear to reside on the steeper L_X-L_R track. This suggests that SMBHs also follow two distinct tracks just as stellar-mass black holes do, and supports the idea that the same physical disk-jet mechanisms are at play across the mass scale.
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23) Daily, multiwavelength Swift monitoring of the neutron star low-mass X-ray binary Cen X-4: evidence for accretion and reprocessing during quiescence
Fredirico Bernadini, Ed Cackett, Ed Brown, Caroline D'Angelo, Nathalie Degenaar, Jon Miller, Mark Reynolds, Rudy Wijnands 2013, MNRAS, 436, 2465: We conducted the first long-term (60 d), multiwavelength (optical, ultraviolet, UV, and X-ray) simultaneous monitoring of Cen X-4 with daily Swift observations from 2012 June to August, with the goal of understanding variability in the low-mass X-ray binary Cen X-4 during quiescence. We found Cen X-4 to be highly variable in all energy bands on time-scales from days to months, with the strongest quiescent variability a factor of 22 drop in the X-ray count rate in only 4 d. The X-ray, UV and optical (V band) emission are correlated on time-scales down to less than 110 s. The shape of the correlation is a power law with index γ about 0.2-0.6. The X-ray spectrum is well fitted by a hydrogen neutron star (NS) atmosphere (kT = 59-80 eV) and a power law (with spectral index Γ = 1.4-2.0), with the spectral shape remaining constant as the flux varies. Both components vary in tandem, with each responsible for about 50 per cent of the total X-ray flux, implying that they are physically linked. We conclude that the X-rays are likely generated by matter accreting down to the NS surface. Moreover, based on the short time-scale of the correlation, we also unambiguously demonstrate that the UV emission cannot be due to either thermal emission from the stream impact point, or a standard optically thick, geometrically thin disc. The spectral energy distribution shows a small UV emitting region, too hot to arise from the accretion disc, that we identified as a hotspot on the companion star. Therefore, the UV emission is most likely produced by reprocessing from the companion star, indeed the vertical size of the disc is small and can only reprocess a marginal fraction of the X-ray emission. We also found the accretion disc in quiescence to likely be UV faint, with a minimal contribution to the whole UV flux.
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22) Swift Discovery of a New Soft Gamma Repeater, SGR J1745-29, near Sagittarius A*
Jamie Kennea, Dave Burrows, Chryssa Kouveliotou, David Palmer, Ersin Gogus, Yuki Kaneko, Phil Evans, Nathalie Degenaar, Mark Reynolds, Jon Miller, Rudy Wijnands, Kaya Mori, Neil Gehrels, 2013, ApJ, 770, 24: Starting in 2013 February, Swift has been performing short daily monitoring observations of the G2 gas cloud near Sgr A* with the X-Ray Telescope to determine whether the cloud interaction leads to an increase in the flux from the Galactic center. On 2013 April 24 Swift detected an order of magnitude rise in the X-ray flux from the region near Sgr A*. Initially thought to be a flare from Sgr A*, the detection of a short hard X-ray burst from the same region by the Burst Alert Telescope suggested that the flare was from an unresolved new Soft Gamma Repeater, SGR J1745-29. Here we present the discovery of SGR J1745-29 by Swift, including analysis of data before, during, and after the burst. We find that the spectrum in the 0.3-10 keV range is well fit by an absorbed blackbody model with kT BB ~= 1 keV and absorption consistent with previously measured values from the quiescent emission from Sgr A*, strongly suggesting that this source is at a similar distance. Only one SGR burst has been detected so far from the new source, and the persistent light curve shows little evidence of decay in approximately two weeks of monitoring after outburst. We discuss this light curve trend and compare it with those of other well covered SGR outbursts. We suggest that SGR J1745-29 belongs to an emerging subclass of magnetars characterized by low burst rates and prolonged steady X-ray emission one to two weeks after outburst onset.
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21) The X-ray flaring properties of Sgr A* during six years of monitoring with Swift
Nathalie Degenaar, Jon Miller, Jamie Kennea, Neil Gehrels, Mark Reynolds, Rudy Wijnands, 2013, ApJ, 769, 155: Starting in 2006, Swift has been targeting a region of ~21'x21' around Sagittarius A* (Sgr A*) with the onboard X-ray telescope. The short, quasi-daily observations offer an unique view of the long-term X-ray behavior of the supermassive black hole. We report on the data obtained between 2006 February and 2011 October, which encompasses 715 observations with a total accumulated exposure time of ~0.8 Ms. A total of six X-ray flares were detected with Swift, which all had an average 2-10 keV luminosity of Lx (1-4)E35 erg/s (assuming a distance of 8 kpc). This more than doubles the number of such bright X-ray flares observed from Sgr A*. One of the Swift-detected flares may have been softer than the other five, which would indicate that flares of similar intensity can have different spectral properties. The Swift campaign allows us to constrain the occurrence rate of bright (Lx > 1E35 erg/s) X-ray flares to be ~0.1-0.2 per day, which is in line with previous estimates. This analysis of the occurrence rate and properties of the X-ray flares seen with Swift offers an important calibration point to asses whether the flaring behavior of Sgr A* changes as a result of its interaction with the gas cloud that is projected to make a close passage in 2013.
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20) A Swift Survey of Accretion onto Stellar Mass Black Holes
Mark Reynolds, Jon Miller, 2013, ApJ, 769, 16: We present a systemic analysis of all of the stellar mass black hole binaries (confirmed < candidate) observed by the Swift observatory up to June 2010. The broad Swift bandpass enables a trace of disk evolution over an unprecedented range in flux and temperature. The final data sample consists of 476 X-ray spectra containing greater than 100 counts, in the 0.6 – 10 keV band. This is the largest sample of high quality CCD spectra of accreting black holes published to date. In addition, strictly simultaneous data at optical/UV wavelengths are available for 255 (54%) of these observations. The data are modelled with a combination of an accretion disk and a hard spectral component. For the hard component we consider both a simple power-law and a thermal Comptonization model. An accretion disk is detected at greater than the 5σ confidence level in 61% of the observations. Lightcurves and color-color diagrams are constructed for each system. Hardness luminosity and disk fraction luminosity diagrams are constructed and are observed to be consistent with those typically observed by RXTE, noting the sensitivity below 2 keV provided by Swift. The observed spectra have an average luminosity of ~ 1% Eddington, though we are sensitive to accretion disks down to a luminosity of 10−3 LEdd. Thus this is also the largest sample of such cool accretion disks studied to date. (Abridged)
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19) G306.3-0.9: A newly discovered young galactic supernova remnant
Mark Reynolds, Shyeh Loi, Tara Murphy, Jon Miller, Dipankar Maitra, Kayhan Gultekin, Neil Gehrels, Jamie Kennea, Michael Siegel, Jonathan Gelbord, Paul Kuin, Vanessa Moss, Sarah Reeves, William Robbins, Bryan Gaensler, Rubens Reis, Robert Petre, 2013, ApJ, 766, 112: We present X-ray and radio observations of the new Galactic supernova remnant (SNR) G306.3-0.9, recently discovered by Swift. Chandra imaging reveals a complex morphology, dominated by a bright shock. The X-ray spectrum is broadly consistent with a young SNR in the Sedov phase, implying an age of 2500 yr for a distance of 8 kpc, plausibly identifying this as one of the 20 youngest Galactic SNRs. Australia Telescope Compact Array (ATCA) imaging reveals a prominent ridge of radio emission that correlates with the X-ray emission. We find a flux density of ~ 160 mJy at 1 GHz, which is the lowest radio flux recorded for a Galactic SNR to date. The remnant is also detected at 24microns, indicating the presence of irradiated warm dust. The data reveal no compelling evidence for the presence of a compact stellar remnant.
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18) The mass of the black hole in GRS 1915+105: new constraints from infrared spectroscopy
Dan Hurley, Paul Callanan, Patrick Elebert, Mark Reynolds, 2013, MNRAS, 430, 1832: GRS 1915+105 has the largest mass function of any Galactic black hole system, although the error is relatively large. Here we present spectroscopic analysis of medium-resolution infrared Very Large Telescope archival data of GRS 1915+105 in the K band. We find an updated ephemeris, and report on attempts to improve the mass function by a refinement of the radial velocity estimate. We show that the spectra are significantly affected by the presence of phase-dependent CO bandhead emission, possibly originating from the accretion disc: we discuss the impact this has on efforts to better constrain the black hole mass. We report on a possible way to measure the radial velocity utilizing apparent H-band atomic absorption features and also discuss the general uncertainty of the system parameters of this well-studied object.
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17) Evidence of Light-Bending Effects and its implication for spectral state transitions
Rubens Reis, Jon Miller, Mark Reynolds, Andy Fabian, Dominic Walton, Ed Cackett, Jack Steiner, 2013, ApJ, 763, 48: It has long been speculated that the nature of the hard X-ray corona may be an important second driver of black hole state transitions, in addition to the mass accretion rate through the disk. However, a clear physical picture of coronal changes has not yet emerged. We present results from a systematic analysis of Rossi X-ray Timing Explorer observations of the stellar mass black hole binary XTE J1650-500. All spectra with significant hard X-ray detections were fit using a self-consistent, relativistically-blurred disk reflection model suited to high ionization regimes. Importantly, we find evidence that both the spectral and timing properties of black hole states may be partially driven by the height of the X-ray corona above the disk, and related changes in how gravitational light bending affects the corona--disk interaction. Specifically, the evolution of the power-law, thermal disk, and relativistically--convolved reflection components in our spectral analysis indicate that: (1) the disk inner radius remains constant at r_in =1.65+/-0.08 GM/c^2 (consistent with values found for the ISCO of XTE J1650-500 in other works) throughout the transition from the brighter phases of the low-hard state to the intermediate states (both the hard-intermediate and soft-intermediate), through to the soft state and back; (2) the ratio between the observed reflected X-ray flux and power-law continuum (the "reflection fraction", R) increases sharply at the transition between the hard-intermediate and soft-intermediate states ("cannonball" jets are sometimes launched at this transition); (3) both the frequency and coherence of the high-frequency quasi-periodic oscillations (QPOs) observed in XTE J1650-500 increase with R. We discuss our results in terms of black hole states and the nature of black hole accretion flows across the mass scale.
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16) A 200-s Quasi-Periodicity Following the Tidal Disruption of a Star by a Dormant Black Hole
Rubens Reis, Jon Miller, Mark Reynolds, Kayhan Gultekin, Dipankar Maitra, Askley King, Tod Strohmayer, 2012, Sci, 337, 949: Supermassive black holes (SMBHs; M \gtrsim 10^5 M_sun) are known to exist at the centre of most galaxies with sufficient stellar mass. In the local Universe, it is possible to infer their properties from the surrounding stars or gas. However, at high redshifts we require active, continuous accretion to infer the presence of the SMBHs, often coming in the form of long-term accretion in active galactic nuclei. SMBHs can also capture and tidally disrupt stars orbiting nearby, resulting in bright flares from otherwise quiescent black holes. Here, we report on a ~200-s X-ray quasi-periodicity around a previously dormant SMBH located in the centre of a galaxy at redshift z=0.3534. This result may open the possibility of probing general relativity beyond our local Universe.
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15) Suzaku Observation of the Black Hole Candidate MAXI J1836-194 in a Hard/Intermediate Spectral State
Rubens Reis, Jon Miller, Mark Reynolds, Andrew Fabian, Dominic Walton, 2012, ApJ, 751, 34): We report on a Suzaku observation of the newly discovered X-ray binary MAXI J1836-194. The source is found to be in the hard/intermediate spectral state and displays a clear and strong relativistically broadened iron emission line. We fit the spectra with a variety of phenomenological, as well as physically motivated disk reflection models, and find that the breadth and strength of the iron line are always characteristic of emission within a few gravitational radii around a black hole. This result is independent of the continuum used and strongly points toward the central object in MAXI J1836-194 being a stellar mass black hole rotating with a spin of a = 0.88 ± 0.03 (90% confidence). We discuss this result in the context of spectral state definitions, physical changes (or lack thereof) in the accretion disk, and on the potential importance of the accretion disk corona in state transitions.
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14) Multimessenger Astronomy with Pulsar Timing and X-ray Observations of Massive Black Hole Binaries
Alberto Sesana, Constanze Roedig, Mark Reynolds, Massimo Dotti, 2012, MNRAS, 420, 860: We demonstrate that very massive (>10^8\msun), cosmologically nearby (z<1) black hole binaries (MBHBs), which are primary targets for ongoing and upcoming pulsar timing arrays (PTAs), are particularly appealing multimessenger carriers. According to current models for massive black hole formation and evolution, the planned Square Kilometer Array (SKA) will collect gravitational wave signals from thousands of such massive systems, being able to individually resolve and locate in the sky several of them (maybe up to a hundred). By employing a standard model for the evolution of MBHBs in circumbinary discs, with the aid of dedicated numerical simulations, we characterize the gas-binary interplay, identifying possible electromagnetic signatures of the PTA sources. We concentrate our investigation on two particularly promising scenarios in the high energy domain, namely, the detection of X-ray periodic variability and of double broad K\alpha iron lines. Up to several hundreds of periodic X-ray sources with a flux >10^-13 erg s^-1 cm^-2 will be in the reach of upcoming X-ray observatories. Double relativistic K\alpha lines may be observable in a handful of low redshift (z<0.3) sources by proposed deep X-ray probes, such as Athena. (Abridged)
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13) A strong emission line near 24.8 angstrom in the X-ray binary system MAXI J0556--332: gravitational redshift or unusual donor?
Dipankar Maitra, Jon Miller, John Raymond, Mark Reynolds, 2011, ApJ, 743, 11: We report the discovery of a strong emission line near 24.8 angstrom (0.5 keV) in the newly discovered X-ray binary system MAXI J0556-332 with the reflection grating spectrometer onboard the XMM-Newton observatory. The X-ray light curve morphology during these observations is complex and shows occasional dipping behavior. Here we present time- and rate-selected spectra from the RGS and show that this strong emission line is unambiguously present in all the XMM observations. The measured line center is consistent with the Ly-alpha transition of N VII in the rest frame. While the spectra contain imprints of absorption lines and edges, there appear to be no other significantly prominent narrow line due to the source itself, thus making the identification of the 24.8 angstrom line uncertain. We discuss possible physical scenarios, including a gravitationally redshifted O VIII Ly-alpha line originating at the surface of a neutron star or an unusual donor with an extremely high N/O abundance (>57) relative to solar, that may have produced this comparatively strong emission line.
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12) An Anomalous Quiescent Stellar Mass Black Hole
Mark Reynolds, Jon Miller, 2011, ApJ, 734, 17: We present the results of a 40 ks Chandra observation of the quiescent stellar mass black hole GS 1354-64. A total of 266 net counts are detected at the position of this system. The resulting spectrum is found to be consistent with the spectra of previously observed quiescent black holes, i.e., a power-law with a photon index of Γ ∼ 2. The inferred luminosity in the 0.5 -- 10 keV band is found to lie in the range 0.5 - 6.5 x 10^{34} erg/s, where the uncertainty in the distance is the dominant source of this large luminosity range. Nonetheless, this luminosity is over an order of magnitude greater than that expected from the known distribution of quiescent stellar mass black hole luminosities and makes GS 1354-64 the only known stellar mass black hole to disagree with this relation. This observation suggests the possibility of significant accretion persisting in the quiescent state.
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11) Ground- and space-based study of two globular cluster cataclysmic variables: M22 CV1 and M5 V101
Anna Hourihane, Paul Callanan, Adrienne Cool, Mark Reynolds, 2011, MNRAS, 414, 184: As a class of compact binaries with large binding energy, cataclysmic variables (CVs) formed through close encounters play an important role in the dynamical evolution of globular clusters. As part of a systematic search for CVs undergoing dwarf nova (DN) eruptions in globular clusters, our 2004 monitoring programme of M22 detected an outburst of the DN candidate CV1 during May. We implement the ISIS image subtraction routine to obtain a light curve for an outburst of CV1. We present the outburst light curve as well as Hubble Space Telescope/Wide-Field Planetary Camera 2 (WFPC2) photometry in the V, U and near-ultraviolet (nUV) bands and a Chandra/Advanced CCD Imaging Spectrometer (ACIS) spectrum of the object. Our results confirm the DN nature of the outburst and the CV status of the object. We also present the results of a ground-based study of another globular cluster CV, M5 V101 - including quiescent medium-resolution William Herschel Telescope (WHT)/Intermediate dispersion Spectrograph and Imaging System (ISIS) spectroscopy in the B and R bands, displaying prominent Balmer and He I emission, and R-band photometry.
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10) A Distinctive Disk-Jet Coupling in the Seyfert-1 AGN NGC 4051
Ashley King, Jon Miller, Edward Cackett, Andy Fabian, Micheal Nowak, Micheal Rupen, Kayhan Gultekin, Mark Reynolds, 2011, ApJ, 729, 19: We report on the results of a simultaneous monitoring campaign employing eight Chandra X-ray (0.5-10 keV) and six VLA/EVLA (8.4 GHz) radio observations of NGC 4051 over seven months. Evidence for compact jets is observed in the 8.4 GHz radio band; This builds on mounting evidence that jet production may be prevalent even in radio-quiet Seyferts. Assuming comparatively negligible local diffuse emission in the nucleus, the results also demonstrate an inverse correlation of L_radio proportional to L_X-ray ^(-0.72+/-0.04) . Current research linking the mass of supermassive black holes and stellar-mass black holes in the "low/hard" state to X-ray luminosities and radio luminosities suggest a "fundamental plane of accretion onto black holes" that has a positive correlation of L_radio proportional to L_X-ray^(0.67+/-0.12) . Our simultaneous results differ from this relation by more than 11 sigma, indicating that a separate mode of accretion and ejection may operate in this system. A review of the literature shows that the inverse correlation seen in NGC 4051 is seen in three other black hole systems, all of which accrete at near 10% of their Eddington luminosity, perhaps suggesting a distinct mode of disk-jet coupling at high Eddington fractions. We discuss our results in the context of disk and jets in black holes and accretion across the black hole mass scale.
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9) Chandra grating spectroscopy of the Be/X-ray binary 1A 0535+262
Mark Reynolds, Jon Miller, 2010, ApJ, 723, 1799: We present Chandra HETGS spectroscopy of the Be/X-ray binary 1A 0535+262 obtained during the 2009/2010 giant outburst. These are the first CCD grating spectra of this type of system during a giant outburst. Our spectra reveal a number of lines including a narrow Fe K_alpha emission line with a FWHM of ~ 5000 km s^-1. For the first time, we detect the presence of a highly ionized outflow in a Be/X-ray binary. Assuming that the line is He-like Fe XXV, fits with a simple Gaussian imply an outflow velocity of ~ 1500 km s^-1. However, self-consistent photoionization modeling with XSTAR suggests that Fe XXIII-XXIV must also contribute. In this case, an outflow velocity of ~ 3000 km s^-1 is implied. These results are discussed in the context of the accretion flow in Be-star, neutron star, and black hole X-ray binaries.
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8) Suzaku Observations of the Galactic Center Microquasar 1E 1740.7-2942
Mark Reynolds, Jon Miller, 2010, ApJ, 716, 1431: We present two Suzaku observations of the Galactic center microquasar 1E 1740.7-2942 separated by approximately 700 days. The source was observed on both occasions after a transition to the spectrally hard state. Significant emission from 1E 1740.7-2942 is detected out to an energy of 300 keV, with no spectral break or turnover evident in the data. We tentatively measure a lower limit to the cut-off energy of ~ 380 keV. The spectra are found to be consistent with a Comptonized corona on both occasions, where the high energy emission is consistent with a hard power-law (\Gamma ~ 1.8) with a significant contribution from an accretion disc with a temperature of ~ 0.4 keV at soft X-ray energies. The measured value for the inner radius of the accretion disc is found to be inconsistent with the picture whereby the disc is truncated at large radii in the low-hard state and instead favours a radius close to the ISCO (R_in ~ 10 - 20 R_g).
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7) Suzaku broadband spectroscopy of Swift J1753.5-0127 in the Low-Hard State
Mark Reynolds, Jon Miller, Jeroen Homan, Giovanni Miniutti, 2010, ApJ, 709, 358: We present Suzaku observations of the Galactic black hole candidate Swift J1753.5-0127 in the low-hard state. The broadband coverage of Suzaku enables us to detect the source over the energy range 0.6 -- 250 keV. The broadband spectrum (2 -- 250 keV) is found to be consistent with a simple power-law (gamma \sim 1.63). In agreement with previous observations of this system, a significant excess of soft X-ray flux is detected consistent with the presence of a cool accretion disc. Estimates of the disc inner radius infer a value consistent with the ISCO (R_{in} \lesssim 6 R_g, for certain values of, e.g. N_H, i), although we cannot conclusively rule out the presence of an accretion disc truncated at larger radii (R_{in} \sim 10 - 50 R_g). A weak, relativistically-broadened iron line is also detected, in addition to disc reflection at higher energy. However, the iron-K line profile favours an inner radius larger than the ISCO (R _{in} \sim 10 - 20 R_g). The implications of these observations for models of the accretion flow in the low-hard state are discussed.
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6) A photometric study of the field around the candidate recoiling/binary black hole SDSS J092712.65+294344.0
Roberto Decarli, Mark Reynolds, Massimo Dotti, 2009, MNRAS, 397, 458: We present a photometric FUV to Ks-band study of the field around quasar SDSS J092712.65+294344.0. The SDSS spectrum of this object shows various emission lines with two distinct redshifts, at z=0.699 and z=0.712. Because of this peculiar spectroscopic feature this source has been proposed as a candidate recoiling or binary black hole. A third alternative model involves two galaxies moving in the centre of a rich galaxy cluster. Here we present a study addressing the possible presence of such a rich cluster of galaxies in the SDSS J092712.65+294344.0 field. We observed the 3.6x2.6 square arcmin field in the Ks-band and matched the NIR data with the FUV and NUV images in the GALEX archive and the ugriz observations in the SDSS. From various colour-colour diagrams we were able to classify the nature of 32 sources, only 6-11 of which have colours consistent with galaxies at z~0.7. We compare these numbers with the surface density of galaxies, stars & quasars, and the expectations for typical galaxy clusters both at low and high redshift. Our study shows that the galaxy cluster scenario is in clear disagreement with the new observations.
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5) Broad Relativistic Iron Line Emission Observed in SAX J1808.4-3658
Edward Cackett, Diego Altamirano, Alessandro Patruno, Jon Miller, Mark Reynolds, Manuel Linares, Rudy Wijnands, 2009, ApJ, 694, 21: During the September-October 2008 outburst of the accreting millisecond pulsar SAX J1808.4-3658, the source was observed by both Suzaku and XMM-Newton approximately 1 day apart. Spectral analysis reveals a broad relativistic Fe K-alpha emission line which is present in both data-sets, as has recently been reported for other neutron star low-mass X-ray binaries. The properties of the Fe K line observed during each observation are very similar. From modeling the Fe line, we determine the inner accretion disk radius to be 13.2 +/- 2.5 GM/c^2. The inner disk radius measured from the Fe K line suggests that the accretion disk is not very receded in the island state. If the inner disk (as measured by the Fe line) is truncated at the magnetospheric radius this implies a magnetic field strength of ~3E8 G at the magnetic poles, consistent with other independent estimates.
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4) Optical Spectroscopy and Photometry of SAX J1808.4-3658 in Outburst
Patrick Elebert, Mark Reynolds, Paul Callanan, Dan Hurley, Gavin Ramsay, Fraser Lewis, Dave Russell, Brian Nord, Stephen Kane, D. LePoy, Pasi Hakala, 2009, MNRAS, 395, 884: We present phase resolved optical spectroscopy and photometry of V4580 Sagittarii, the optical counterpart to the accretion powered millisecond pulsar SAX J1808.4-3658, obtained during the 2008 September/October outburst. Doppler tomography of the N III 4640.64 Bowen blend emission line reveals a focused spot of emission at a location consistent with the secondary star. The velocity of this emission occurs at 324 +/- 15 km/s; applying a "K-correction", we find the velocity of the secondary star projected onto the line of sight to be 370 +/- 40 km/s. Based on existing pulse timing measurements, this constrains the mass ratio of the system to be 0.044^{+0.005}_{-0.004}, and the mass function for the pulsar to be 0.44^{+0.16}_{-0.13} Msun. Combining this mass function with various inclination estimates from other authors, we find no evidence to suggest that the neutron star in SAX J1808.4-3658 is more massive than the canonical value of 1.4 Msun. Our optical light curves exhibit a possible superhump modulation, expected for a system with such a low mass ratio. The equivalent width of the Ca II H and K interstellar absorption lines suggest that the distance to the source is ~2.5 kpc. This is consistent with previous distance estimates based on type-I X-ray bursts which assume cosmic abundances of hydrogen, but lower than more recent estimates which assume helium-rich bursts.
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3) IR Contamination in Galactic XRNe
Mark Reynolds, Paul Callanan, Edward Robinson, Cynthia Froning, 2008, MNRAS, 387, 788: The most widely used means of measuring the mass of black holes in Galactic binaries - specifically the X-ray novae - involves both radial velocity measurements of the secondary star, and photometric measurements of its ellipsoidal variability. The latter is important in constraining the inclination and mass ratio, and requires as direct a measure of the flux of the secondary as possible. Up to now, such measurements have been preferentially carried out in the NIR (1 -- 2.5$\mu m$), where the flux from the cooler secondary is expected to dominate over that from the accretion disc. However, here we present evidence of a significant non-stellar contribution to the NIR flux in many of those quiescent X-ray novae that are thought to contain a black hole primary. We discuss origins of this excess and the effect of such contamination on Galactic black hole mass measurements.
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2) The Light Curve of the Companion to PSR B1957+20
Mark Reynolds, Paul Callanan, Andy Fruchter, Manuel Torres, Martin Beer, Rachel Gibbons, 2007, MNRAS, 379, 1117: We present a new analysis of the light curve for the secondary star in the eclipsing binary millisecond pulsar system PSR B1957+20. Combining previous data and new data points at minimum from the Hubble Space Telescope, we have 100% coverage in the R-band. We also have a number of new K_s-band data points, which we use to constrain the infrared magnitude of the system. We model this with the Eclipsing Light Curve code (ELC). From the modelling with the ELC code we obtain colour information about the secondary at minimum light in BVRI and K. For our best fit model we are able to constrain the system inclination to 65 +/- 2 degrees for pulsar masses ranging from 1.3 -- 1.9 M_sun. The pulsar mass is unconstrained. We also find that the secondary star is not filling its Roche lobe. The temperature of the un-irradiated side of the companion is in agreement with previous estimates and we find that the observed temperature gradient across the secondary star is physically sustainable.
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1) Keck K-band Observations of GRO J0422+32
Mark Reynolds, Paul Callanan, Alex Filippenko, 2007, MNRAS, 374, 657: We present Keck K-band photometry and low-resolution H & K-band spectroscopy of the X-ray nova GRO J0422+32 obtained while the system was in the quiescent state. No clear ellipsoidal modulation is present in the light curve, which is instead dominated by a strong flickering component. In the K-band we observe strong Br_gamma emission, with an equivalent width of 38 +/- 5 Angstroms. From this we conclude that the accretion disc is the most likely source of the observed photometric contamination, and that previous infrared-based attempts to constrain the mass of the putative black hole in this system are prone to considerable uncertainty. We finally proceed to show how it is possible to place meaningful constraints on some of the binary parameters of this system, even in the presence of a relatively high level of contamination from the disc.
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Conference Proceedings

The Swift Galactic Plane Survey: Mark Reynolds, Jon Miller, Dipankar Maitra, Kayhan Gultekin, Jamie Kennea, Mike Siegel, Neil Gehrels, Jonathon Gelbord, Paul Kuin
2011 High Energy Astrophysics Division meeting, Newport, Rhode Island, USA, 7th-10th September, 2011
The Jet and Windds in Seyfert-1 NGC 4051: Ashley King, Jon Miller, Andy Fabian, Ed Cackett, Sera Markoff, Mike Rupen, Kayhan Gultekin, Mark Reynolds, Mike Nowak, John Raymond
2011 High Energy Astrophysics Division meeting, Newport, Rhode Island, USA, 7th-10th September, 2011
Galactic X-Ray Binaries as observed by Swift: Mark Reynolds, Jon Miller
Swift Mission Conference Celebrating 5 Years, State College, Pennsylvania, USA, 18-20 November, 2009
The Nature of the Accretion Flow in the Low-Hard State: Mark Reynolds, Jon Miller
X-ray Astronomy 2009 Present status, multi-wavelength approach and future perspectives, Bologna, Italy, 7-11 September, 2009
Suzaku Observations of the Gacactic Center Microquasar 1E 1740.7-2942: Mark Reynolds, Jon Miller
X-ray Astronomy 2009 Present status, multi-wavelength approach and future perspectives, Bologna, Italy, 7-11 September, 2009
Suzaku Broadband Spectroscopy Of The Black Hole Candidate Swift J1753.5-0127: Mark Reynolds, Jon Miller, Jeroen Homan
2009, 213th meeting of the American Astronomical Society, Long Beach, California, 4-8 January
The Optical Counterparts of Binary Millisecond Pulsars in Quiescence: Paul Callanan, Mark Reynolds, Patrick Elebert, Alex Filippenko, Ryan Foley, Peter Garnavich, Glen Mackie
2006, 26th Texas Symposium on Relatavistic Astrophysics, Melbourne University, 11-15 December
On the Reliability of Galactic Black Hole Mass Estimates from Ellipsoidal IR Studies: Mark Reynolds, Paul Callanan
2006, 26th Texas Symposium on Relatavistic Astrophysics, Melbourne University, 11-15 December
IR Observations of Quiescent Black Hole XRNe: Mark Reynolds, Paul Callanan
Black Holes: From Stars to Galaxies - Across the Range of Masses, International Astronomical Union. Symposium no. 238, held 21-25 August, 2006 in Prague, Czech Republic, S238, 149
Optical Observations of Binary Millisecond X-ray Pulsars in Quiescence: Paul Callanan, Mark Reynolds, Alex Filippenko, Peter Garnavich, Ryan Foley
On the Present and Future of Pulsar Astronomy, 26th meeting of the IAU, Joint Discussion 2, 16-17 August, 2006, Prague, Czech Republic, JD02, 58
Keck IR Observation of GRO J0422+32 in Quiescence: Mark Reynolds, Paul Callanan, Alex Filippenko
2005, A Life with stars, A meeting in honour of the 65th birthday of Ed van den Heuvel, eds Kapers, van der Klis, Wijers
Optical Observations of IGR J00291+5934 in the Post Outburst Phase: Mark Reynolds, Patrick Elebert, Paul Callanan, Brian Field, Patrick Tuite, Manuel Torres, Danny Steeghs, Peter Garnavich, Don Terndrup, Alex Filippenko, Ryan Foley, Emilios Harlaftis
Populations of High Energy Sources in Galaxies Proceedings of the 230th Symposium of the International Astronomical Union, Held in Dublin, Ireland 15-19 August 2005, Edited by E. J. A. Meurs; G. Fabbiano. Cambridge: Cambridge University Press, 2006., pp.80-81
The Optical & IR Lightcurve of PSR B1957+20: Mark Reynolds, Paul Callanan, Andrew Fruchter, Manuel Torres, Martin Beer, Rachel Gibbons
Populations of High Energy Sources in Galaxies Proceedings of the 230th Symposi um of the International Astronomical Union, Held in Dublin, Ireland 15-19 August 2005, Edited by E. J. A. Meurs; G. Fabbiano. Cambridge: Cambridge University Press, 2006., pp.55-56
The Light Curve of the Companion to PSR B1957+20: Mark Reynolds, Paul Callanan, Andrew Fruchter, Manuel Torres, Martin Beer, Rachel Gibbons
INTERACTING BINARIES: Accretion, Evolution, and Outcomes. AIP Conference Proceedings, Volume 797, pp. 607-610

Circulars

Astronomer's Telegram #5200 -- Swift Galactic Plane Survey: Sourcelist v3.0: Mark Reynolds, Jon Miller, Dipankar Maitra, Kayhan Gultekin, Neil Gehrels, Jamie Kennea, Mike Siegel, Jonathon Gelbord, Paul Kuin
Astronomer's Telegram #5016 -- Continued Swift Monitoring of the Galactic Center Flare: Mark Reynolds, Nathalie Degenaar, Jon Miller, Jamie Kennea, Rudy Wijnands
Astronomer's Telegram #5009 -- Swift/BAT detection of an SGR-like flare from near Sgr A*: Jamie Kennea, Hans Krimm, Scott Barthelmy, Neil Gehrels, Criag Markwardt, Jay Cummings, Frank Marshall, Takanori Sakamoto, Nathalie Degenaar, Mark Reynolds, Jon Miller, Chryssa Kouveliotou
Astronomer's Telegram #5006 -- Large Flare from Sgr A* Detected by Swift: Nathalie Degenaar, Mark Reynolds, Jon Miller, Jamie Kennea, Rudy Wijnands
Astronomer's Telegram #4318 -- Swift Galactic Plane Survey: Sourcelist v2.0: Mark Reynolds, Jon Miller, Dipankar Maitra, Kayhan Gultekin, Neil Gehrels, Jamie Kennea, Mike Siegel, Jonathon Gelbord, Paul Kuin
Astronomer's Telegram #4295 -- New radio detection of MAXI J1910-057 in hard-state transition: Ashley King, Jon Miller, Nathalie Degenaar, Mark Reynolds, Rubens Reis
Astronomer's Telegram #4191 -- Chandra Spectroscopy of MAXI J1305-704: Jon Miller, Jon Raymond, Jamie Kennea, Andy Beardmore, Mark Reynolds, Dipankar Maitra, Nathalie Degenaar, Ed Cackett, Andy Fabian, Chris Reynolds
Astronomer's Telegram #4071 -- MAXI J1305-704 may be an Eclipsing Source: Jamie Kennea, Jon Miller, Andy Beardmore, Nathalie Degenaar, Mark Reynolds
Astronomer's Telegram #4070 -- Swift Detection of Ionized X-ray Absorption in MAXI J1305-704: Jon Miller, Andy Beardmore, Jamie Kennea, Mark Reynolds, Ashley King, Andy Fabian, Chris Reynolds, John Raymond
Astronomer's Telegram #3963 -- A Candidate SNR Discovered in the Swift Galactic Plane Survey: Mark Reynolds, Jon Miller, Dipankar Maitra, Kayhan Gultekin, Neil Gehrels, Jamie Kennea, Mike Siegel, Jonathon Gelbord, Paul Kuin
Astronomer's Telegram #3951 -- Swift Galactic Plane Survey: Sourcelist v1.0: Mark Reynolds, Jon Miller, Dipankar Maitra, Kayhan Gultekin, Neil Gehrels, Jamie Kennea, Mike Siegel, Jonathon Gelbord, Paul Kuin
Astronomer's Telegram #3415 -- Discovery of a New Supernova Remnant in the Swift Galactic Plane Survey: Jon Miller, Mark Reynolds, Dipankar Maitra, Kayhan Gultekin, Neil Gehrels, Jamie Kennea, Mike Siegel, Jonathon Gelbord, Paul Kuin
Astronomer's Telegram #3349 -- Discovery of a strong emission line at 0.5 keV in MAXI J0556-332 with the RGS on XMM-Newton: Dipankar Maitra, Mark Reynolds, Jon Miller, John Raymond
Astronomer's Telegram #3327 -- Rebrightening of MAXI J0556-332: Dipankar Maitra, Mark Reynolds, Peter Curran, Kayhan Gultekin, Jon Miller, Jamie Kennea, Dave Russell
Astronomer's Telegram #2744 -- X-ray, UV, Optical and NIR Observations of Aql X-1: Dipankar Maitra, Mark Reynolds, Jon M. Miller, Kayhan Gultekin
Astronomer's Telegram #2742 -- New X-ray Activity from Aql X-1: Kayhan Gultekin, Dipankar Maitra, Jon M. Miller Mark Reynolds
Astronomer's Telegram #2343 -- Swift XRT observation of 1A 0535+262: Mark Reynolds, Jon Miller
Astronomer's Telegram #2125 -- NIR Imaging of the Candidate Black Hole Transient XTE J1652-453: Mark Reynolds, Paul Callanan, Takahiro Nagayama
Astronomer's Telegram #1844 -- Broad relativistic iron line observed in SAX J1808.4-3658 by Suzaku: Edward Cackett, Diego Altamirano, Jon Miller, Mark Reynolds, Jennifer Blum, Manuel Linares, Alessandro Patruno, Rudy Wijnands
Astronomer's Telegram #1752 -- ESO VLT spectral observations of SAX J1808.4-3658 in outburst: Gavin Ramsay, Patrick Elebert, Paul Callanan, Mark Reynolds, Pasi Hakala
Astronomer's Telegram #1601 -- Possible near-infrared counterpart to the Galactic transient 1RXH J173523.7-354013: Edward Cackett, Rudy Wijnands, Mark Reynolds
Astronomer's Telegram #1110 -- Optical measurements of HETE J1900.1-2455 with the Large Binocular Telescope: Peter Garnavich, Paul Callanan, Patrick Elebert, Mark Reynolds