Suzaku Observation of Two Ultraluminous X-Ray Sources in NGC 1313

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dc.creatorMizuno, T.
dc.creatorMiyawaki, R.
dc.creatorEbisawa, K.
dc.creatorKubota, A.
dc.creatorMiyamoto, M.
dc.creatorWinter, L.
dc.creatorUeda, Y.
dc.creatorIsobe, N.
dc.creatorDewangan, G.
dc.creatorDone, C.
dc.creatorGriffiths, R. E.
dc.creatorHaba, Y.
dc.creatorKokubun, M.
dc.creatorKotoku, J.
dc.creatorMakishima, K.
dc.creatorMatsushita, K.
dc.creatorMushotzky, R. F.
dc.creatorNamiki, M.
dc.creatorPetre, R.
dc.creatorTakahashi, H.
dc.creatorTamagawa, T.
dc.creatorTerashima, Y.
dc.date2006-10-06
dc.date.accessioned2026-07-07T11:42:38Z
dc.date.available2026-07-07T11:42:38Z
dc.descriptionTwo ultraluminous X-ray sources (ULXs) in the nearby Sb galaxy NGC 1313, named X-1 and X-2, were observed with Suzaku on 2005 September 15. During the observation for a net exposure of 28~ks (but over a gross time span of 90~ks), both objects varied in intensity by about 50~%. The 0.4--10 keV X-ray luminosity of X-1 and X-2 was measured as $2.5 \times 10^{40}~{\rm erg~s^{-1}}$ and $5.8 \times 10^{39}~{\rm erg~s^{-1}}$, respectively, with the former the highest ever reported for this ULX. The spectrum of X-1 can be explained by a sum of a strong and variable power-law component with a high energy cutoff, and a stable multicolor blackbody with an innermost disk temperature of $\sim 0.2$ keV. These results suggest that X-1 was in a ``very high'' state, where the disk emission is strongly Comptonized. The absorber within NGC 1313 toward X-1 is suggested to have a subsolar oxygen abundance. The spectrum of X-2 is best represented, in its fainter phase, by a multicolor blackbody model with the innermost disk temperature of 1.2--1.3 keV, and becomes flatter as the source becomes brighter. Hence X-2 is interpreted to be in a slim-disk state. These results suggest that the two ULXs have black hole masses of a few tens to a few hundreds solar masses.
dc.descriptionaccepted for publication in PASJ
dc.identifierhttps://arxiv.org/abs/astro-ph/0610185
dc.identifierhttp://arxiv.org/abs/astro-ph/0610185
dc.identifierProg.Theor.Phys.Suppl.169:229-233,2007
dc.identifierdoi:10.1143/PTPS.169.229
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/200950
dc.subjectAstrophysics
dc.titleSuzaku Observation of Two Ultraluminous X-Ray Sources in NGC 1313
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