ar X iv : a st ro - p h / 05 06 32 8 v 1 1 4 Ju n 20 05 Study of 23 day periodicity of Blazar Mkn 501 in 1997

ar X iv : a st ro - p h / 05 06 29 8 v 1 1 4 Ju n 20 05 The application of slim disk models to ULX : the case of M 33 X - 8

A comparative XMM-Newton archival data spectral study of the ultraluminous Xray source (ULX) M33 X-8 has been performed by using both the standard disk model and the newly developed slim disk models. The results of this analysis tend to confirm the hypothesis that M33 X-8 is an X-ray binary with a stellar-mass black hole accreting at super-Eddington rate.

ar X iv : a st ro - p h / 99 04 05 7 v 1 5 A pr 1 99 9 Evidence for Intergalactic Absorption in the TeV Gamma - Ray Spectrum of Mkn 501

The recent HEGRA observations of the blazar Mkn 501 show strong curvature in the very high energy γ-ray spectrum. Applying the γ-ray opacity derived from an empirically based model of the intergalactic infrared background radiation field (IIRF), to these observations, we find that the intrinsic spectrum of this source is consistent with a power-law: dNγ/dE ∝ E −α with α = 2.00 ± 0.03 over the r...

ar X iv : a st ro - p h / 05 06 44 9 v 4 1 9 Ju n 20 06 Can a dust dominated universe have accelerated expansion ?

Recently, there has been suggestions that the apparent accelerated expansion of the universe is due not to a cosmological constant, but rather to inhomogeneities in the distribution of matter. In this work, we investigate a specific class of inhomogeneous models that can be solved analytically, namely the dust-dominated Lemâitre-Tolman-Bondi universe models. We show that they do not permit acce...

ar X iv : a st ro - p h / 04 06 56 7 v 1 2 4 Ju n 20 04 1

ar X iv : a st ro - p h / 00 02 43 1 v 1 2 3 Fe b 20 00 CONSTRAINTS TO THE SSC MODEL FOR MKN 501

We fit the SEDs of the TeV blazar Mkn 501 adopting the homogeneous SynchrotronSelf Compton model to simultaneous X-ray and TeV spectra recently become available. We present detailed model spectra calculated with the above constraints and taking into account the absorption of TeV photons by the IR background. We found that the curved TeV spectra can be naturally reproduced even without IRB absor...