Evidence for Returning Disk Radiation in the Black Hole X-Ray Binary XTE J1550–564

Connors, Riley; García, Javier A.; Dauser, Robert C.; Grinberg, V.; Steiner, James F.; Sridhar, Navin; Wilms, J.; Tomsick, John A.; Harrison, Fiona A.; Licklederer, Stefan

doi:10.3847/1538-4357/ab7afc

Cited by 50 publications

(78 citation statements)

References 66 publications

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“…In addition, we should expect the bright disk emission to be contributing to the disk ionization, which makes the drop in flux even more suspect. This issue was highlighted in full by Connors et al (2020), and is possibly evidence that an IC continuum is an inappropriate description of the irradiating continuum in BHB soft states (due to the superior disk flux with respect to the IC emission). We address this in modeling of the NuSTAR and Swift-XRT data in Section 3.2.…”

Section: Spectral Fitting Resultsmentioning

confidence: 99%

“…There is still work to be done to characterize the evolution of BHB reflection properties, and their dependence on the disk density, during the transition from the hard to soft states. Recent work has focused on tracking the key accretion flow properties of BHBs with advanced reflection models (e.g., Connors et al 2020;Sridhar et al 2020), showing that as BHBs transition from the hard to the soft state, the illuminating continuum may be evolving from a power-law-like coronal spectrum to a more disk-blackbody-like spectrum due to the luminosity of the disk. Thus, a comprehensive picture of the evolving accretion flow during transition and into the soft state requires a full treatment of both density effects and the impact of returning disk emission.…”

Section: Introductionmentioning

confidence: 99%

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Reflection Modeling of the Black Hole Binary 4U 1630–47: The Disk Density and Returning Radiation

Connors

García

Tomsick

et al. 2021

ApJ

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We present the analysis of X-ray observations of the black hole binary 4U 1630−47 using relativistic reflection spectroscopy. We use archival data from the Rossi X-ray Timing Explorer, Neil Gehrels Swift Observatory, and Nuclear Spectroscopic Telescope Array observatories, taken during different outbursts of the source between 1998 and 2015. Our modeling includes two relatively new advances in modern reflection codes: high-density disks, and returning thermal disk radiation. Accretion disks around stellar-mass black holes are expected to have densities well above the standard value assumed in traditional reflection models (i.e., n e ∼ 10 15 cm −3 ). New high-density reflection models have important implications in the determination of disk truncation (i.e., the disk inner radius). This is because one must retain self-consistency in the irradiating flux and corresponding disk ionization state, which is a function of disk density and system geometry. We find that the disk density is n e 10 20 cm −3 across all spectral states. This density, combined with our constraints on the ionization state of the material, implies an irradiating flux impinging on the disk that is consistent with the expected theoretical estimates. Returning thermal disk radiation-the fraction of disk photons that bend back to the disk producing additional reflection components -is expected predominantly in the soft state. We show that returning radiation models indeed provide a better fit to the soft-state data, reinforcing previous results that show that in the soft state, the irradiating continuum may be blackbody emission from the disk itself. Unified Astronomy Thesaurus concepts: Accretion (14); Stellar accretion disks (1579); Black hole physics (159); Atomic physics (2063); Low-mass x-ray binary stars (939)

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Section: Spectral Fitting Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reflection Modeling of the Black Hole Binary 4U 1630–47: The Disk Density and Returning Radiation

Connors

García

Tomsick

et al. 2021

ApJ

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“…They find that up to 58 per cent of the thermal emission can return to the the disc. Connors et al (2020) find that the X-ray reflection spectrum detected in the black hole X-ray binary XTE J1550−564 during the soft, disc-dominated accretion state is best described by a disc illuminated by a thermal blackbody spectrum rather than by a power-law spectrum from the corona, suggesting that returning radiation is indeed significant and that it is the reflection of returning thermal emission that is detected.…”

Section: Introductionmentioning

confidence: 90%

Returning radiation in strong gravity around black holes: reverberation from the accretion disc

Wilkins

García

Dauser

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We study reflected X-ray emission that returns to the accretion disc in the strong gravitational fields around black holes using General Relativistic ray tracing and radiative transfer calculations. Reflected X-rays that are produced when the inner regions of the disc are illuminated by the corona are subject to strong gravitational light bending, causing up to 47 per cent of the reflected emission to be returned to the disc around a rapidly spinning black hole, depending upon the scale height of the corona. The iron Kα line is enhanced relative to the continuum by 25 per cent, and the Compton hump by up to a factor of three. Additional light travel time between primary and secondary reflections increases the reverberation time lag measured in the iron K band by 49 per cent, while the soft X-ray lag is increased by 25 per cent and the Compton hump response time is increased by 60 per cent. Measured samples of X-ray reverberation lags are shown to be consistent with X-rays returning to the accretion disc in strong gravity. Understanding the effects of returning radiation is important in interpreting reverberation observations to probe black holes. Reflected X-rays returning to the disc can be uniquely identified by blueshifted returning iron K line photons that are Compton scattered from the inner disc, producing excess, delayed emission in the 3.5-4.5 keV energy range that will be detectable with forthcoming X-ray observatories, representing a unique test of General Relativity in the strong field limit.

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“…The vertical gray bars indicate the characteristic energies of phenomenological models. region modeled by bbody (Fabian et al 2020), and returning radiation approximated by relxillNS (Connors et al 2020). Other possibilities include extra Comptonization of the reflection spectrum in the corona (Wilkins & Gallo 2015;Steiner et al 2017), or a change in the disk thickness as the mass accretion rate rises.…”

Section: Time-averaged Flux Spectral Fittingmentioning

confidence: 99%

Disk, Corona, Jet Connection in the Intermediate State of MAXI J1820+070 Revealed by NICER Spectral-timing Analysis

Wang

Mastroserio

Kara

et al. 2021

ApJL

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101

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We analyze five epochs of Neutron star Interior Composition Explorer (NICER) data of the black hole X-ray binary MAXI J1820+070 during the bright hard-to-soft state transition in its 2018 outburst with both reflection spectroscopy and Fourier-resolved timing analysis. We confirm the previous discovery of reverberation lags in the hard state, and find that the frequency range where the (soft) reverberation lag dominates decreases with the reverberation lag amplitude increasing during the transition, suggesting an increasing X-ray emitting region, possibly due to an expanding corona. By jointly fitting the lag-energy spectra in a number of broad frequency ranges with the reverberation model reltrans, we find the increase in reverberation lag is best described by an increase in the X-ray coronal height. This result, along with the finding that the corona contracts in the hard state, suggests a close relationship between spatial extent of the X-ray corona and the radio jet. We find the corona expansion (as probed by reverberation) precedes a radio flare by ∼5 days, which may suggest that the hard-to-soft transition is marked by the corona expanding vertically and launching a jet knot that propagates along the jet stream at relativistic velocities.Unified Astronomy Thesaurus concepts: Low-mass x-ray binary stars (939); Stellar mass black holes (1611); High energy astrophysics (739); Black hole physics (159); X-ray transient sources (1852)

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Evidence for Returning Disk Radiation in the Black Hole X-Ray Binary XTE J1550–564

Cited by 50 publications

References 66 publications

Reflection Modeling of the Black Hole Binary 4U 1630–47: The Disk Density and Returning Radiation

Reflection Modeling of the Black Hole Binary 4U 1630–47: The Disk Density and Returning Radiation

Returning radiation in strong gravity around black holes: reverberation from the accretion disc

Disk, Corona, Jet Connection in the Intermediate State of MAXI J1820+070 Revealed by NICER Spectral-timing Analysis

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