Discovery of spectral transitions from two ultraluminous compact x-ray sources in IC 342

Aya Kubota, T. Mizuno, K. Makishima, Y. Fukazawa, J. Kotoku, T. Ohnishi, M. Tashiro

研究成果: Article

98 引用 (Scopus)

抄録

Two ASCA observations were made of two ultraluminous compact X-ray sources (ULXs) in the spiral galaxy IC 342. In the 1993 observation, source 2 showed a 0.5-10 keV luminosity of 6 × 1039 ergs s-1 (assuming a distance of 4.0 Mpc) and a hard power-law spectrum of photon index ∼1.4. As already reported, source 1 was ∼3 times brighter on that occasion and exhibited a soft spectrum represented by a multicolor disk model with an inner-disk temperature of ∼1.8 keV. The second observation, made in 2000 February, revealed that source 1 had made a transition into a hard spectral state, while source 2 made a transition into a soft spectral state. The ULXs are therefore inferred to exhibit two distinct spectral states, and they sometimes make transitions between them. These results significantly reinforce the scenario that describes ULXs as mass-accreting black holes.

元の言語English
ジャーナルAstrophysical Journal
547
発行部数2 PART 2
DOI
出版物ステータスPublished - 2001 2 1
外部発表Yes

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x ray sources
erg
power law
x rays
spiral galaxies
temperature
luminosity
photons

ASJC Scopus subject areas

  • Space and Planetary Science

これを引用

Kubota, A., Mizuno, T., Makishima, K., Fukazawa, Y., Kotoku, J., Ohnishi, T., & Tashiro, M. (2001). Discovery of spectral transitions from two ultraluminous compact x-ray sources in IC 342. Astrophysical Journal, 547(2 PART 2). https://doi.org/10.1086/318903

Discovery of spectral transitions from two ultraluminous compact x-ray sources in IC 342. / Kubota, Aya; Mizuno, T.; Makishima, K.; Fukazawa, Y.; Kotoku, J.; Ohnishi, T.; Tashiro, M.

:: Astrophysical Journal, 巻 547, 番号 2 PART 2, 01.02.2001.

研究成果: Article

Kubota, A, Mizuno, T, Makishima, K, Fukazawa, Y, Kotoku, J, Ohnishi, T & Tashiro, M 2001, 'Discovery of spectral transitions from two ultraluminous compact x-ray sources in IC 342', Astrophysical Journal, 巻. 547, 番号 2 PART 2. https://doi.org/10.1086/318903
Kubota, Aya ; Mizuno, T. ; Makishima, K. ; Fukazawa, Y. ; Kotoku, J. ; Ohnishi, T. ; Tashiro, M. / Discovery of spectral transitions from two ultraluminous compact x-ray sources in IC 342. :: Astrophysical Journal. 2001 ; 巻 547, 番号 2 PART 2.
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abstract = "Two ASCA observations were made of two ultraluminous compact X-ray sources (ULXs) in the spiral galaxy IC 342. In the 1993 observation, source 2 showed a 0.5-10 keV luminosity of 6 × 1039 ergs s-1 (assuming a distance of 4.0 Mpc) and a hard power-law spectrum of photon index ∼1.4. As already reported, source 1 was ∼3 times brighter on that occasion and exhibited a soft spectrum represented by a multicolor disk model with an inner-disk temperature of ∼1.8 keV. The second observation, made in 2000 February, revealed that source 1 had made a transition into a hard spectral state, while source 2 made a transition into a soft spectral state. The ULXs are therefore inferred to exhibit two distinct spectral states, and they sometimes make transitions between them. These results significantly reinforce the scenario that describes ULXs as mass-accreting black holes.",
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AU - Kubota, Aya

AU - Mizuno, T.

AU - Makishima, K.

AU - Fukazawa, Y.

AU - Kotoku, J.

AU - Ohnishi, T.

AU - Tashiro, M.

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N2 - Two ASCA observations were made of two ultraluminous compact X-ray sources (ULXs) in the spiral galaxy IC 342. In the 1993 observation, source 2 showed a 0.5-10 keV luminosity of 6 × 1039 ergs s-1 (assuming a distance of 4.0 Mpc) and a hard power-law spectrum of photon index ∼1.4. As already reported, source 1 was ∼3 times brighter on that occasion and exhibited a soft spectrum represented by a multicolor disk model with an inner-disk temperature of ∼1.8 keV. The second observation, made in 2000 February, revealed that source 1 had made a transition into a hard spectral state, while source 2 made a transition into a soft spectral state. The ULXs are therefore inferred to exhibit two distinct spectral states, and they sometimes make transitions between them. These results significantly reinforce the scenario that describes ULXs as mass-accreting black holes.

AB - Two ASCA observations were made of two ultraluminous compact X-ray sources (ULXs) in the spiral galaxy IC 342. In the 1993 observation, source 2 showed a 0.5-10 keV luminosity of 6 × 1039 ergs s-1 (assuming a distance of 4.0 Mpc) and a hard power-law spectrum of photon index ∼1.4. As already reported, source 1 was ∼3 times brighter on that occasion and exhibited a soft spectrum represented by a multicolor disk model with an inner-disk temperature of ∼1.8 keV. The second observation, made in 2000 February, revealed that source 1 had made a transition into a hard spectral state, while source 2 made a transition into a soft spectral state. The ULXs are therefore inferred to exhibit two distinct spectral states, and they sometimes make transitions between them. These results significantly reinforce the scenario that describes ULXs as mass-accreting black holes.

KW - Black hole physics

KW - Galaxies: spiral

KW - X-rays: galaxies

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