Colors and patterns of black hole X-ray binary GX 339-4

Abstract

Black hole X-ray binaries show signs of nonthermal emission in the optical to near-infrared range. We analyzed optical to near-infrared SMARTS data on GX 339-4 over the 2002–2011 period. Using soft state data, we estimated the interstellar extinction toward the source and characteristic color temperatures of the accretion disk. We show that various spectral states of regular outbursts occupy similar regions on color-magnitude diagrams, and that transitions between the states proceed along the same tracks despite substantial differences in the morphology of the observed light curves. We determine the typical duration of hard-to-soft and soft-to-hard state transitions and the hard state at the decaying stage of the outburst to be one, two, and four weeks, respectively. We find that the failed outbursts cannot be easily distinguished from the regular outbursts at their early stages, but if the source reaches 16 mag in V band, it transits to the soft state. By subtracting the contribution of the accretion disk, we obtain spectra of the nonthermal component, which have constant, nearly flat shapes during the transitions between the hard and soft states. In contrast to the slowly evolving nonthermal component seen at optical and near-infrared wavelengths, the mid-infrared spectrum is strongly variable on short timescales and sometimes shows a prominent excess with a cutoff below 1014 Hz. We show that the radio to optical spectrum can be modeled using three components corresponding to the jet, hot flow, and irradiated accretion disk.

Disk-jet coupling changes as a possible indicator for outbursts from GX 339-4 remaining within the X-ray hard state

“…Therefore, the 2017-2018 X-ray outburst of GX 339−4 seems to follow a relatively typical evolution when compared to the Xray behaviour of both hard-only and successful outbursts, with no preliminary indicators that may identify whether an outburst is successful or not. A similar result was also found during detailed nearinfrared (NIR) and optical studies of outbursts from BH LMXBs (Kosenkov et al 2020), where no indicators in the NIR/optical colours or magnitude were identified that might allow for an identification of a hard-only or successful outburst.…”

The prototype X-ray binary GX 339–4: using TeV γ-rays to assess LMXBs as Galactic cosmic ray accelerators

“…In particular, we find that the scenario where optical emission originates from the jet base and the IR emission originates from the particle acceleration region z diss is consistent with the data. An alternative scenario is that both the IR and the optical emission originate in a hot flow that consists of thermal and non-thermal electrons (Poutanen & Veledina 2014 ;Kosenkov et al 2020 ), a scenario that better describes the soft states (Kosenkov & Veledina 2018 ). Further simultaneous IR-to-optical observations in the hard state would be able to test this scenario, as well as simultaneous polarization measurements across the entire optical/IR band (although see e.g.…”

The prototype X-ray binary GX 339-4: using TeV gamma-rays to assess LMXBs as Galactic cosmic ray accelerators

“…In particular, we find that the scenario where optical emission originates from the jet base and the IR emission originates from the particle acceleration region 𝑧 diss is consistent with the data. An alternative scenario is that both the IR and the optical emission originate in a hot flow that consists of thermal and non-thermal electrons (Poutanen & Veledina 2014;Kosenkov et al 2020), a scenario that better describes the soft states (Kosenkov & Veledina 2018). Further simultaneous IR-to-optical observations in the hard state would be able to test this scenario, as well as simultaneous polarisation measurements across the entire optical/IR band (although see e.g., Russell & Fender 2008 for measurements prior to the 2010 outburst).…”