Optical and near-infrared spectroscopy of the black hole GX 339-4 - I. A focus on the continuum in the low/hard and high/soft states

F. Rahoui, M. Coriat, S. Corbel, M. Cadolle Bel, J. A. Tomsick, J. C. Lee, J. Rodriguez, Dave Russell, S. Migliari

Research output: Contribution to journalArticle

Abstract

The microquasar GX 339-4, known to exhibit powerful compact jets that dominate its radio to near-infrared emission, entered an outburst in 2010 for the fifth time in about 15yr. An extensive radio to X-ray multiwavelength campaign was immediately triggered, and we report here on European Southern Observatory/FORS2+ISAAC optical and near-infrared spectroscopic observations, supported by Australia Telescope Compact Array radio and Rossi X-ray Timing Experiment/Swift X-ray quasi-simultaneous data. GX 339-4 was observed at three different epochs, once in the soft state and twice in the hard state. In the soft state, the optical and near-infrared continuum is largely consistent with the Raleigh-Jeans tail of a thermal process. As an explanation, we favour irradiation of the outer accretion disc by its inner regions, enhanced by disc warping. An excess is also present at low frequencies, likely due to an M subgiant companion star. During the first hard state, the optical/near-infrared continuum is well described by the optically thin synchrotron emission of the compact jet combined with disc irradiation and perhaps another component peaking in the ultraviolet. The spectral break where the jet transits from the optically thick to thin regimes, located below 1.20 × 10 14Hz, is not detected and the extension of the optically thin synchrotron is consistent with the 3-50keV spectrum. In contrast, the emission during the second hard state is more difficult to understand and points towards a more complex jet continuum. In both cases, the near-infrared continuum is found to be variable at time-scales at least as short as 20s, although these variabilities are smoothed out beyond a few hundred seconds. This implies rapid variations - in flux and frequency - of the location of the spectral break, i.e. dramatic short time-scale changes of the physical conditions at the base of the jet, such as the magnetic field and/or the base radius.

Original languageEnglish (US)
Pages (from-to)2202-2212
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume422
Issue number3
DOIs
StatePublished - May 1 2012

Fingerprint

infrared spectroscopy
near infrared
continuums
radio
irradiation
synchrotrons
subgiant stars
time measurement
timescale
companion stars
x rays
transit
European Southern Observatory
accretion disks
outburst
observatory
accretion
telescopes
low frequencies
magnetic field

Keywords

  • Accretion, accretion discs
  • Binaries: close
  • Infrared: stars
  • ISM: jets and outflows
  • Stars: individual: GX 339-4
  • X-rays: binaries

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Optical and near-infrared spectroscopy of the black hole GX 339-4 - I. A focus on the continuum in the low/hard and high/soft states. / Rahoui, F.; Coriat, M.; Corbel, S.; Cadolle Bel, M.; Tomsick, J. A.; Lee, J. C.; Rodriguez, J.; Russell, Dave; Migliari, S.

In: Monthly Notices of the Royal Astronomical Society, Vol. 422, No. 3, 01.05.2012, p. 2202-2212.

Research output: Contribution to journalArticle

Rahoui, F. ; Coriat, M. ; Corbel, S. ; Cadolle Bel, M. ; Tomsick, J. A. ; Lee, J. C. ; Rodriguez, J. ; Russell, Dave ; Migliari, S. / Optical and near-infrared spectroscopy of the black hole GX 339-4 - I. A focus on the continuum in the low/hard and high/soft states. In: Monthly Notices of the Royal Astronomical Society. 2012 ; Vol. 422, No. 3. pp. 2202-2212.
@article{37c0200fc95542898d1fc338138147ae,
title = "Optical and near-infrared spectroscopy of the black hole GX 339-4 - I. A focus on the continuum in the low/hard and high/soft states",
abstract = "The microquasar GX 339-4, known to exhibit powerful compact jets that dominate its radio to near-infrared emission, entered an outburst in 2010 for the fifth time in about 15yr. An extensive radio to X-ray multiwavelength campaign was immediately triggered, and we report here on European Southern Observatory/FORS2+ISAAC optical and near-infrared spectroscopic observations, supported by Australia Telescope Compact Array radio and Rossi X-ray Timing Experiment/Swift X-ray quasi-simultaneous data. GX 339-4 was observed at three different epochs, once in the soft state and twice in the hard state. In the soft state, the optical and near-infrared continuum is largely consistent with the Raleigh-Jeans tail of a thermal process. As an explanation, we favour irradiation of the outer accretion disc by its inner regions, enhanced by disc warping. An excess is also present at low frequencies, likely due to an M subgiant companion star. During the first hard state, the optical/near-infrared continuum is well described by the optically thin synchrotron emission of the compact jet combined with disc irradiation and perhaps another component peaking in the ultraviolet. The spectral break where the jet transits from the optically thick to thin regimes, located below 1.20 × 10 14Hz, is not detected and the extension of the optically thin synchrotron is consistent with the 3-50keV spectrum. In contrast, the emission during the second hard state is more difficult to understand and points towards a more complex jet continuum. In both cases, the near-infrared continuum is found to be variable at time-scales at least as short as 20s, although these variabilities are smoothed out beyond a few hundred seconds. This implies rapid variations - in flux and frequency - of the location of the spectral break, i.e. dramatic short time-scale changes of the physical conditions at the base of the jet, such as the magnetic field and/or the base radius.",
keywords = "Accretion, accretion discs, Binaries: close, Infrared: stars, ISM: jets and outflows, Stars: individual: GX 339-4, X-rays: binaries",
author = "F. Rahoui and M. Coriat and S. Corbel and {Cadolle Bel}, M. and Tomsick, {J. A.} and Lee, {J. C.} and J. Rodriguez and Dave Russell and S. Migliari",
year = "2012",
month = "5",
day = "1",
doi = "10.1111/j.1365-2966.2012.20763.x",
language = "English (US)",
volume = "422",
pages = "2202--2212",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "3",

}

TY - JOUR

T1 - Optical and near-infrared spectroscopy of the black hole GX 339-4 - I. A focus on the continuum in the low/hard and high/soft states

AU - Rahoui, F.

AU - Coriat, M.

AU - Corbel, S.

AU - Cadolle Bel, M.

AU - Tomsick, J. A.

AU - Lee, J. C.

AU - Rodriguez, J.

AU - Russell, Dave

AU - Migliari, S.

PY - 2012/5/1

Y1 - 2012/5/1

N2 - The microquasar GX 339-4, known to exhibit powerful compact jets that dominate its radio to near-infrared emission, entered an outburst in 2010 for the fifth time in about 15yr. An extensive radio to X-ray multiwavelength campaign was immediately triggered, and we report here on European Southern Observatory/FORS2+ISAAC optical and near-infrared spectroscopic observations, supported by Australia Telescope Compact Array radio and Rossi X-ray Timing Experiment/Swift X-ray quasi-simultaneous data. GX 339-4 was observed at three different epochs, once in the soft state and twice in the hard state. In the soft state, the optical and near-infrared continuum is largely consistent with the Raleigh-Jeans tail of a thermal process. As an explanation, we favour irradiation of the outer accretion disc by its inner regions, enhanced by disc warping. An excess is also present at low frequencies, likely due to an M subgiant companion star. During the first hard state, the optical/near-infrared continuum is well described by the optically thin synchrotron emission of the compact jet combined with disc irradiation and perhaps another component peaking in the ultraviolet. The spectral break where the jet transits from the optically thick to thin regimes, located below 1.20 × 10 14Hz, is not detected and the extension of the optically thin synchrotron is consistent with the 3-50keV spectrum. In contrast, the emission during the second hard state is more difficult to understand and points towards a more complex jet continuum. In both cases, the near-infrared continuum is found to be variable at time-scales at least as short as 20s, although these variabilities are smoothed out beyond a few hundred seconds. This implies rapid variations - in flux and frequency - of the location of the spectral break, i.e. dramatic short time-scale changes of the physical conditions at the base of the jet, such as the magnetic field and/or the base radius.

AB - The microquasar GX 339-4, known to exhibit powerful compact jets that dominate its radio to near-infrared emission, entered an outburst in 2010 for the fifth time in about 15yr. An extensive radio to X-ray multiwavelength campaign was immediately triggered, and we report here on European Southern Observatory/FORS2+ISAAC optical and near-infrared spectroscopic observations, supported by Australia Telescope Compact Array radio and Rossi X-ray Timing Experiment/Swift X-ray quasi-simultaneous data. GX 339-4 was observed at three different epochs, once in the soft state and twice in the hard state. In the soft state, the optical and near-infrared continuum is largely consistent with the Raleigh-Jeans tail of a thermal process. As an explanation, we favour irradiation of the outer accretion disc by its inner regions, enhanced by disc warping. An excess is also present at low frequencies, likely due to an M subgiant companion star. During the first hard state, the optical/near-infrared continuum is well described by the optically thin synchrotron emission of the compact jet combined with disc irradiation and perhaps another component peaking in the ultraviolet. The spectral break where the jet transits from the optically thick to thin regimes, located below 1.20 × 10 14Hz, is not detected and the extension of the optically thin synchrotron is consistent with the 3-50keV spectrum. In contrast, the emission during the second hard state is more difficult to understand and points towards a more complex jet continuum. In both cases, the near-infrared continuum is found to be variable at time-scales at least as short as 20s, although these variabilities are smoothed out beyond a few hundred seconds. This implies rapid variations - in flux and frequency - of the location of the spectral break, i.e. dramatic short time-scale changes of the physical conditions at the base of the jet, such as the magnetic field and/or the base radius.

KW - Accretion, accretion discs

KW - Binaries: close

KW - Infrared: stars

KW - ISM: jets and outflows

KW - Stars: individual: GX 339-4

KW - X-rays: binaries

UR - http://www.scopus.com/inward/record.url?scp=84862777012&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84862777012&partnerID=8YFLogxK

U2 - 10.1111/j.1365-2966.2012.20763.x

DO - 10.1111/j.1365-2966.2012.20763.x

M3 - Article

AN - SCOPUS:84862777012

VL - 422

SP - 2202

EP - 2212

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 3

ER -