منابع مشابه
0 v 1 1 2 Ja n 20 07 Quasi - Periodic Variability in NGC 5408 X - 1
We report the discovery with XMM-Newton of quasiperiodic variability in the 0.2 10 keV X-ray flux from the ultraluminous X-ray source NGC 5408 X-1. The average power spectrum of all EPIC-pn data reveals a strong 20 mHz QPO with an average amplitude (rms) of 9%, and a coherence, Q ≡ ν0/σ ≈ 6. In a 33 ksec time interval when the 20 mHz QPO is strongest we also find evidence for a 2nd QPO peak at ...
متن کاملX - ray flares from the ultra - luminous X - ray source in NGC 5408
We have studied an ultra-luminous X-ray source (ULX) in the dwarf galaxy NGC 5408 with a series of XMM-Newton observations, between 2001 July and 2003 January. We find that its X-ray spectrum is best fitted with a power law of photon index Γ ≈ 2.6–2.9 and a thermal component with blackbody temperature kT bb ≈ 0.12–0.14 keV. These spectral features, and the inferred luminosity ≈ 10 40 erg s −1 i...
متن کاملX-ray Spectral Variability in Ngc
NGC 3783 was observed for approximately 210 ks by Suzaku and in this time showed significant spectral and flux variability at both short (20 ks) and long (100 ks) timescales. The full observation is found to consist of approximately six “spectral periods” where the behavior of the soft (0.3–1.0 keV) and hard (2–10 keV) bands are somewhat distinct. Using a variety of methods we find that the str...
متن کاملThe ROSAT view of NGC 1365 and the luminous highly variable off-nuclear X-ray source NGC 1365–X1
We present an X-ray spectral and spatial analysis of the composite starburst/Seyfert galaxy NGC1365. Excellent fits of the ROSAT PSPC spectrum are obtained by combining a soft thermal component with a hard powerlaw. The hard component may be either seen directly or can be explained by scattering of the AGN powerlaw at circumnuclear warm high-column-density gas. A compilation of the multi-wavele...
متن کاملWeighing the black holes in ultraluminous X-ray sources through timing
We describe a new method to estimate the mass of black holes in Ultraluminous X-ray Sources (ULXs). The method is based on the recently discovered “variability plane”, populated by Galactic stellar-mass black-hole candidates (BHCs) and supermassive active galactic nuclei (AGNs), in the parameter space defined by the black-hole mass, accretion rate and characteristic frequency. We apply this met...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2007
ISSN: 0004-637X,1538-4357
DOI: 10.1086/512723