Constraints on Relativistic Jets in Quiescent Black Hole X-ray Binaries from Broadband Spectral Modeling

Abstract

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~1e-8.5 L_Edd). Our new spectral energy distribution (SED) includes the radio, near-infrared, optical, ultraviolet, and X-ray wavebands. XTE J1118 is now the second BHXB at such a low Eddington ratio with a well-sampled SED, providing new constraints on highly sub-Eddington accretion flows and jets, and opening the door for comparison studies. 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 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 associated with the jet base. The corresponding (thermal) synchrotron component emits primarily in the infrared through ultraviolet wavebands. Our results on XTE J1118 are consistent with broadband modeling for A0620-00 and for Sgr A*. 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.

16 pages, 2 figures, 3 Tables. Accepted for publication in MNRAS

References in corpus (13)

• X-ray Properties of Black-Hole Binaries
• A Long, Hard Look at the Low-Hard State in Accreting Black Holes
• A radio-emitting outflow in the quiescent state of A0620-00: implications for modelling low-luminosity black hole binaries
• The radio/X-ray domain of black hole X-ray binaries at the lowest radio luminosities
• Revisiting the radio/X-ray flux correlation in the black hole V404 Cyg: from outburst to quiescence
• Results from an extensive simultaneous broadband campaign on the underluminous active nucleus M81*: further evidence for mass-scaling accretion in black holes
• The spectral energy distribution of quiescent black hole X-ray binaries: new constraints from Spitzer
• Tracing the jet contribution to the mid-IR over the 2005 outburst of GRO J1655-40 via broadband spectral modeling
• The Quiescent X-ray Spectrum of Accreting Black Holes
• Further Evidence for Variable Synchrotron Emission in XTE J1118+480 in Outburst
• Swift J1357.2-0933: the faintest black hole?
• Exploring plasma evolution during Sagittarius A* flares
• The 2005 outburst of the halo black hole X-ray transient XTE J1118+480

Cited by in corpus (17)

• Relativistic Jets in Active Galactic Nuclei und Microquasars
• The ultracompact nature of the black hole candidate X-ray binary 47 Tuc X9
• The black hole transient MAXI J1348-630: evolution of the compact and transient jets during its 2019/2020 outburst
• The 2015 Decay of the Black Hole X-ray Binary V404 Cygni: Robust Disk-Jet Coupling and a Sharp Transition into Quiescence
• Multiwavelength observations of the black hole X-ray binary A0620-00 in quiescence
• Mapping Jet-ISM Interactions in X-ray Binaries with ALMA: A GRS 1915$+$105 Case Study
• Up and Down the Black Hole Radio/X-ray Correlation: the 2017 mini-outbursts from Swift J1753.5-0127
• Radio & X-ray detections of GX 339--4 in quiescence using MeerKAT and Swift
• Sub-mm Jet Properties of the X-Ray Binary Swift J1745$-$26
• Observations of the Disk/Jet Coupling of MAXI J1820+070 During its Descent to Quiescence
• Polarized synchrotron emission in quiescent black hole X-ray transients
• GS 2000+25: The Least Luminous Black Hole X-ray Binary
• ALMA observations of A0620-00: fresh clues on the nature of quiescent black hole X-ray binary jets
• Toward a Larger Sample of Radio Jets from Quiescent Black Hole X-ray Binaries
• Scale-invariance of black hole accretion: modeling emission from a black hole X-ray binary with relativistic accretion flow simulations
• The black hole X-ray binary MAXI J1348$-$630 in quiescence
• X-ray Spectra From Weakly Magnetized Accretion Flows