Suzaku observation of the black hole binary 4U 1630-47 in the very high state

Takafumi Hori, Yoshihiro Ueda, Megumi Shidatsu, Taiki Kawamuro, Aya Kubota, Chris Done, Satoshi Nakahira, Kohji Tsumura, Mai Shirahata, Takahiro Nagayama

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

We report the results from an X-ray and near-infrared observation of the Galactic black hole binary 4U 1630-47 in the very high state (VHS), performed with Suzaku and the Infrared Survey Facility around the peak of the 2012 September-October outburst. The X-ray spectrum is approximated by a steep power law, with photon index of 3.2, identifying the source as being in the VHS. A more detailed fit shows that the X-ray continuum is well described by a multicolor disk, together with thermal and nonthermal Comptonization. The inner disk appears slightly truncated by comparison with a previous high/soft state of this source, even taking into account energetic coupling between the disk and corona, although there are uncertainties due to the dust-scattering correction. The near-infrared fluxes are higher than the extrapolated disk model, showing that there is a contribution from irradiation in the outer disk and/or the companion star at these wavelengths. Our X-ray spectra do not show the Doppler-shifted iron emission lines indicating a baryonic jet that were seen four days previously in an XMM-Newton observation, despite the source being in a similar state. There are also no significant absorption lines from highly ionized iron lines as are seen in the previous high/soft state data. We show that the increased source luminosity is not enough on its own to make the wind so highly ionized as to be undetectable. This shows that the disk wind has changed in terms of its launch radius and/or density compared to the high/soft state.

Original languageEnglish
Article number20
JournalAstrophysical Journal
Volume790
Issue number1
DOIs
Publication statusPublished - 2014 Jul 20

Fingerprint

near infrared
iron
x rays
outburst
corona
companion stars
irradiation
power law
energetics
scattering
XMM-Newton telescope
dust
wavelength
newton
coronas
luminosity
continuums
radii
photons
wavelengths

Keywords

  • accretion, accretion disks
  • black hole physics
  • stars: individual (4U 1630-47)
  • X-rays: binaries

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Suzaku observation of the black hole binary 4U 1630-47 in the very high state. / Hori, Takafumi; Ueda, Yoshihiro; Shidatsu, Megumi; Kawamuro, Taiki; Kubota, Aya; Done, Chris; Nakahira, Satoshi; Tsumura, Kohji; Shirahata, Mai; Nagayama, Takahiro.

In: Astrophysical Journal, Vol. 790, No. 1, 20, 20.07.2014.

Research output: Contribution to journalArticle

Hori, T, Ueda, Y, Shidatsu, M, Kawamuro, T, Kubota, A, Done, C, Nakahira, S, Tsumura, K, Shirahata, M & Nagayama, T 2014, 'Suzaku observation of the black hole binary 4U 1630-47 in the very high state', Astrophysical Journal, vol. 790, no. 1, 20. https://doi.org/10.1088/0004-637X/790/1/20
Hori, Takafumi ; Ueda, Yoshihiro ; Shidatsu, Megumi ; Kawamuro, Taiki ; Kubota, Aya ; Done, Chris ; Nakahira, Satoshi ; Tsumura, Kohji ; Shirahata, Mai ; Nagayama, Takahiro. / Suzaku observation of the black hole binary 4U 1630-47 in the very high state. In: Astrophysical Journal. 2014 ; Vol. 790, No. 1.
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N2 - We report the results from an X-ray and near-infrared observation of the Galactic black hole binary 4U 1630-47 in the very high state (VHS), performed with Suzaku and the Infrared Survey Facility around the peak of the 2012 September-October outburst. The X-ray spectrum is approximated by a steep power law, with photon index of 3.2, identifying the source as being in the VHS. A more detailed fit shows that the X-ray continuum is well described by a multicolor disk, together with thermal and nonthermal Comptonization. The inner disk appears slightly truncated by comparison with a previous high/soft state of this source, even taking into account energetic coupling between the disk and corona, although there are uncertainties due to the dust-scattering correction. The near-infrared fluxes are higher than the extrapolated disk model, showing that there is a contribution from irradiation in the outer disk and/or the companion star at these wavelengths. Our X-ray spectra do not show the Doppler-shifted iron emission lines indicating a baryonic jet that were seen four days previously in an XMM-Newton observation, despite the source being in a similar state. There are also no significant absorption lines from highly ionized iron lines as are seen in the previous high/soft state data. We show that the increased source luminosity is not enough on its own to make the wind so highly ionized as to be undetectable. This shows that the disk wind has changed in terms of its launch radius and/or density compared to the high/soft state.

AB - We report the results from an X-ray and near-infrared observation of the Galactic black hole binary 4U 1630-47 in the very high state (VHS), performed with Suzaku and the Infrared Survey Facility around the peak of the 2012 September-October outburst. The X-ray spectrum is approximated by a steep power law, with photon index of 3.2, identifying the source as being in the VHS. A more detailed fit shows that the X-ray continuum is well described by a multicolor disk, together with thermal and nonthermal Comptonization. The inner disk appears slightly truncated by comparison with a previous high/soft state of this source, even taking into account energetic coupling between the disk and corona, although there are uncertainties due to the dust-scattering correction. The near-infrared fluxes are higher than the extrapolated disk model, showing that there is a contribution from irradiation in the outer disk and/or the companion star at these wavelengths. Our X-ray spectra do not show the Doppler-shifted iron emission lines indicating a baryonic jet that were seen four days previously in an XMM-Newton observation, despite the source being in a similar state. There are also no significant absorption lines from highly ionized iron lines as are seen in the previous high/soft state data. We show that the increased source luminosity is not enough on its own to make the wind so highly ionized as to be undetectable. This shows that the disk wind has changed in terms of its launch radius and/or density compared to the high/soft state.

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