Abstract
We report on the X-ray spectral analysis and time evolution of GRS 1739−278 during its 2014 outburst, based on MAXI/GSC and Swift/XRT observations. Over the course of the outburst, a transition from the low/hard state to the high/soft state and then back to the low/hard state was seen. During the high/soft state, the innermost disk temperature mildly decreased, while the innermost radius estimated with the multi-color disk model remained constant at ∼18 (D/8.5 kpc)(cos i/cos 30◦)−1/2 km, where D is the source distance and i is the inclination of observation. This small innermost radius of the accretion disk suggests that the central object is more likely to be a Kerr black hole rather than a Schwardzschild black hole. Applying a relativistic disk emission model to the high/soft state spectra, a mass upper limit of 18.3 M was obtained based on the inclination limit i < 60◦ for an assumed distance of 8.5 kpc. Using the empirical relation of the transition luminosity to the Eddington limit, the mass is constrained to 4.0–18.3 M for the same distance. The mass can be further constrained to be no larger than 9.5 M by adopting the constraints based on the fits to the NuSTAR spectra with relativistically blurred disk reflection models (Miller et al. 2015, ApJ, 799, L6).
| Original language | English |
|---|---|
| Article number | psy058 |
| Journal | Publications of the Astronomical Society of Japan |
| Volume | 70 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 2018 Aug 1 |
| Externally published | Yes |
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Keywords
- Accretion
- Accretion disks
- Stars: black holes
- X-rays: binaries
- X-rays: individual (GRS 1739−278)
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
Cite this
State transitions of GRS 1739−278 in the 2014 outburst. / Wang, Sili; Kawai, Nobuyuki; Shidatsu, Megumi; Tachibana, Yutaro; Yoshii, Taketoshi; Sudo, Masayuki; Kubota, Aya.
In: Publications of the Astronomical Society of Japan, Vol. 70, No. 4, psy058, 01.08.2018.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - State transitions of GRS 1739−278 in the 2014 outburst
AU - Wang, Sili
AU - Kawai, Nobuyuki
AU - Shidatsu, Megumi
AU - Tachibana, Yutaro
AU - Yoshii, Taketoshi
AU - Sudo, Masayuki
AU - Kubota, Aya
PY - 2018/8/1
Y1 - 2018/8/1
N2 - We report on the X-ray spectral analysis and time evolution of GRS 1739−278 during its 2014 outburst, based on MAXI/GSC and Swift/XRT observations. Over the course of the outburst, a transition from the low/hard state to the high/soft state and then back to the low/hard state was seen. During the high/soft state, the innermost disk temperature mildly decreased, while the innermost radius estimated with the multi-color disk model remained constant at ∼18 (D/8.5 kpc)(cos i/cos 30◦)−1/2 km, where D is the source distance and i is the inclination of observation. This small innermost radius of the accretion disk suggests that the central object is more likely to be a Kerr black hole rather than a Schwardzschild black hole. Applying a relativistic disk emission model to the high/soft state spectra, a mass upper limit of 18.3 M was obtained based on the inclination limit i < 60◦ for an assumed distance of 8.5 kpc. Using the empirical relation of the transition luminosity to the Eddington limit, the mass is constrained to 4.0–18.3 M for the same distance. The mass can be further constrained to be no larger than 9.5 M by adopting the constraints based on the fits to the NuSTAR spectra with relativistically blurred disk reflection models (Miller et al. 2015, ApJ, 799, L6).
AB - We report on the X-ray spectral analysis and time evolution of GRS 1739−278 during its 2014 outburst, based on MAXI/GSC and Swift/XRT observations. Over the course of the outburst, a transition from the low/hard state to the high/soft state and then back to the low/hard state was seen. During the high/soft state, the innermost disk temperature mildly decreased, while the innermost radius estimated with the multi-color disk model remained constant at ∼18 (D/8.5 kpc)(cos i/cos 30◦)−1/2 km, where D is the source distance and i is the inclination of observation. This small innermost radius of the accretion disk suggests that the central object is more likely to be a Kerr black hole rather than a Schwardzschild black hole. Applying a relativistic disk emission model to the high/soft state spectra, a mass upper limit of 18.3 M was obtained based on the inclination limit i < 60◦ for an assumed distance of 8.5 kpc. Using the empirical relation of the transition luminosity to the Eddington limit, the mass is constrained to 4.0–18.3 M for the same distance. The mass can be further constrained to be no larger than 9.5 M by adopting the constraints based on the fits to the NuSTAR spectra with relativistically blurred disk reflection models (Miller et al. 2015, ApJ, 799, L6).
KW - Accretion
KW - Accretion disks
KW - Stars: black holes
KW - X-rays: binaries
KW - X-rays: individual (GRS 1739−278)
UR - http://www.scopus.com/inward/record.url?scp=85071504451&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85071504451&partnerID=8YFLogxK
U2 - 10.1093/pasj/psy058
DO - 10.1093/pasj/psy058
M3 - Article
VL - 70
JO - Publication of the Astronomical Society of Japan
JF - Publication of the Astronomical Society of Japan
SN - 0004-6264
IS - 4
M1 - psy058
ER -