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- Title
X-ray and optical observations of the black hole candidate MAXI J1828−249.
- Authors
Oda, Sonoe; Shidatsu, Megumi; Nakahira, Satoshi; Tamagawa, Toru; Moritani, Yuki; Itoh, Ryosuke; Ueda, Yoshihiro; Negoro, Hitoshi; Makishima, Kazuo; Kawai, Nobuyuki; Mihara, Tatehiro
- Abstract
We report results from X-ray and optical observations of the Galactic black hole candidate MAXI J1828−249 performed with Suzaku and the Kanata telescope around the X-ray flux peak in the 2013 outburst. The time-averaged X-ray spectrum covering 0.6–168 keV was approximately characterized by a strong multi-color disk blackbody component with an inner disk temperature of ∼0.6 keV, and a power-law tail with a photon index of ∼2.0. We detected an additional structure at 5–10 keV, which can be modeled neither with X-ray reflection on the disk nor relativistic broadening of the disk emission. Instead, it was successfully reproduced with a Comptonization of disk photons by thermal electrons with a relatively low temperature (≲10 keV). We infer that the source was in the intermediate state, considering its long-term trend in the hardness intensity diagram, the strength of the spectral power-law tail, and its variability properties. The low-temperature Comptonization component could be produced in a boundary region between the truncated standard disk and the hot inner flow, or a Comptonizing region that somehow developed above the disk surface. The multi-wavelength spectral energy distribution suggests that the optical and ultraviolet fluxes were dominated by irradiated outer disk emission.
- Subjects
BLACK holes; SPECTRAL energy distribution; THERMAL electrons; NEUTRINO detectors; X-ray reflection; X-rays; HAWKING radiation
- Publication
Publications of the Astronomical Society of Japan, 2019, Vol 71, Issue 5, pN.PAG
- ISSN
0004-6264
- Publication type
Article
- DOI
10.1093/pasj/psz091