Evidence for quiescent synchrotron emission in the black hole X-ray transient Swift J1357.2−0933

Shahbaz, T.; Russell, D. M.; Zurita, C.; Casares, J.; Corral-Santana, J. M.; Dhillon, V. S.; Marsh, T. R.

doi:10.1093/mnras/stt1212

Cited by 84 publications

(126 citation statements)

References 69 publications

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“…Furthermore, the BHXB Swift J1357.2-0933 was recently suggested to have the lowest quiescent X-ray luminosity of any known BHXB (Armas Padilla et al 2014), making it suitable for comparisons to J1118 and A0620-00. Swift J1357.2-0933 has a very steep NIR-optical spectrum (αν = −1.4) in quiescence, which is also consistent with synchrotron radiation from a thermal distribution of electrons in a weak jet (Shahbaz et al 2013). Thus, the best-fit model for J1118 in Figure 1 may indeed represent the baseline accretion/jet properties for quiescent black holes.…”

Section: Jets In Quiescencesupporting

confidence: 53%

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Constraints on relativistic jets in quiescent black hole X-ray binaries from broad-band spectral modelling

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Gallo

Markoff

et al. 2014

Monthly Notices of the Royal Astronomical Society

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The nature of black hole jets at the lowest detectable luminosities remains an open question, largely due to a dearth of observational constraints. Here, we present a new, nearly-simultaneous broadband spectrum of the black hole X-ray binary (BHXB) XTE J1118+480 at an extremely low Eddington ratio (L X ∼ 10 −8.5 L Edd ). Our new spectral energy distribution (SED) includes the radio, near-infrared, optical, ultraviolet, and X-ray wavebands. XTE J1118+480 is now the second BHXB at such a low Eddington ratio with a well-sampled SED, thereby providing new constraints on highly sub-Eddington accretion flows and jets, and opening the door to begin comparison studies between systems. We apply a multi-zone jet model to the new broadband SED, and we compare our results to previous fits to the same source using the same model at 4-5 decades higher luminosity. We find that after a BHXB transitions to the so-called quiescent spectral state, the jet base becomes more compact (by up to an order of magnitude) and slightly cooler (by at least a factor of two). Our preferred model fit indicates that jet particle acceleration is much weaker after the transition into quiescence. That is, accelerated non-thermal particles no longer reach high enough Lorentz factors to contribute significant amounts of synchrotron X-ray emission. Instead, the X-ray waveband is dominated by synchrotron self-Compton emission from a population of mildly relativistic electrons with a quasi-thermal velocity distribution that are associated with the jet base. The corresponding (thermal) synchrotron component from the jet base emits primarily in the infrared through ultraviolet wavebands. Our results on XTE J1118+480 are consistent with broadband modeling for A0620-00 (the only other comparably low Eddington ratio BHXB with a well-sampled SED) and for Sgr A* (the quiescent supermassive black hole at the Galactic center). The above could therefore represent a canonical baseline geometry for accreting black holes in quiescence. We conclude with suggestions for future studies to further investigate the above scenario.

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Section: Jets In Quiescencesupporting

confidence: 53%

“…Quiescent BHXBs are known to experience a lowlevel of flux variability (e.g., Khargharia et al 2013;Shahbaz et al 2013;Bernardini & Cackett 2014, and references therein). Muno & Mauerhan (2006) estimate that a level of flux variability in the IR of ∼30% could be reasonable.…”

Section: Non-simultaneous Infrared Datamentioning

confidence: 99%

Constraints on relativistic jets in quiescent black hole X-ray binaries from broad-band spectral modelling

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Gallo

Markoff

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…Intriguingly, Shahbaz et al (2013) find that, superposed on the dips, there is stochastic, large-amplitude optical/NIR variability (the fractional optical rms is ≈35%). This variability is highlighted by 10-30 m flare events with amplitudes up to 1.5-2 mag.…”

Section: Introductionmentioning

confidence: 92%

“…Each timeresolved image represents 1000 s of exposure time, except for the first J-band image which includes 500 s. We do not detect any obvious short-term variability that is significantly larger than the uncertainty on each flux measurement: the magnitudes in each sliced J, H, and Ks image vary by ±0.16, 0.14, and 0.06 mag, respectively, but uncertainties on each magnitude measurement are typically comparable, with σm ≈ ±0.13, 0.09, and 0.10 mag, respectively in each filter. We are likely not sensitive to the short-term NIR variability observed by Shahbaz et al (2013), given the cadence and length of our NIR exposures.…”

Section: Near-infraredmentioning

confidence: 99%

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A clean sightline to quiescence: multiwavelength observations of the high Galactic latitude black hole X-ray binary Swift J1357.2−0933

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Gallo

Jonker

et al. 2015

Mon. Not. R. Astron. Soc.

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We present coordinated multiwavelength observations of the high Galactic latitude (b=+50 • ) black hole X-ray binary (BHXB) Swift J1357.2−0933 in quiescence. Our broadband spectrum includes strictly simultaneous radio and X-ray observations, and near-infrared, optical, and ultraviolet data taken 1-2 days later. We detect Swift J1357.2−0933 at all wavebands except for the radio (f 5GHz <3.9 µJy beam −1 ; 3σ rms ). Given current constraints on the distance (2.3-6.3 kpc), its 0.5-10 keV X-ray flux corresponds to an Eddington ratio L X /L Edd = 4 × 10 −9 − 3 × 10 −8 (assuming a black hole mass of 10M ⊙ ). The broadband spectrum is dominated by synchrotron radiation from a relativistic population of outflowing thermal electrons, which we argue to be a common signature of short-period quiescent BHXBs. Furthermore, we identify the frequency where the synchrotron radiation transitions from optically thick-to-thin (ν b ≈ 2 − 5 × 10 14 Hz, which is the most robust determination of a 'jet break' for a quiescent BHXB to date. Our interpretation relies on the presence of steep curvature in the ultraviolet spectrum, a frequency window made observable by the low amount of interstellar absorption along the line of sight. High Galactic latitude systems like Swift J1357.2−0933 with clean ultraviolet sightlines are crucial for understanding black hole accretion at low luminosities.

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Energy‐dependent timing studies of the low‐hard state of black hole X‐ray binaries with XMM‐Newton

Stiele

Kong

2019

Astron Nachr

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Almost all low-mass black hole X-ray binaries are transient sources. Most of these sources show a hysteresis: they evolve from the low-hard state through intermediate state(s) into the high-soft state and then return to the hard state at lower luminosity, again passing through the intermediate states. However, there are outbursts that remain in the hard state (so called "failed" outbursts). While mean X-ray spectra allow us to study the time-averaged spectral shape, we need to make use of "variability spectra," like, for example, covariance spectra, to investigate the variability of individual spectral components on different time scales. Comprehensive studies of covariance spectra of a sample of black hole X-ray binaries observed in the low-hard state of "normal" outbursts revealed an increase of the covariance ratios toward lower energies that has been interpreted as the sign of additional disk variability on long time scales. In the case of GX 339-4, we found that the covariance ratio increases and steeps during outburst decay, consistent with increased disk instabilities. There are two sources (H 1743-322 and GS 1354-64) that do not show an increase toward lower energies in their covariance ratio. We show that there is no correlation between the shape of the covariance ratio and the amount of fractional rms variability. Both these sources have been observed during "failed" outbursts and their photon indices are at the hard end of the photon index range usually observed in black hole X-ray binaries. KEYWORD accretion -accretion disks -binaries: close -black hole physics -X-rays: binaries 1

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Evidence for quiescent synchrotron emission in the black hole X-ray transient Swift J1357.2−0933

Cited by 84 publications

References 69 publications

Constraints on relativistic jets in quiescent black hole X-ray binaries from broad-band spectral modelling

Constraints on relativistic jets in quiescent black hole X-ray binaries from broad-band spectral modelling

A clean sightline to quiescence: multiwavelength observations of the high Galactic latitude black hole X-ray binary Swift J1357.2−0933

Energy‐dependent timing studies of the low‐hard state of black hole X‐ray binaries with XMM‐Newton

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