Solen Balman — Page 2

arXiv2006

The Inclination Angle of and Mass of the Black Hole in XTE J1118+480

We have obtained optical and infrared photometry of the quiescent soft X-ray transient XTE J1118+480. In addition to optical and J-band variations, we present the first observed H- and K_s-band ellipsoidal variations for this system. We model the variations in all bands simultaneously with the WD98 light curve modeling code. The infrared colors of the secondary star in this system are consistent with a K7V, while there is evidence for light from the accretion disk in the optical. Combining the models with the observed spectral energy distribution of the system, the most likely value for the orbital inclination angle is 68 +/- 2 deg. This inclination angle corresponds to a primary black hole mass of 8.53 +/- 0.60 M_sun. Based on the derived physical parameters and infrared colors of the system, we determine a distance of 1.72 +/- 0.10 kpc to XTE J1118+480.

astro-ph↗

arXiv2005

The Chandra Observation of the Shell of Nova Persei 1901 (GK Persei): Detection of localized Non-thermal X-ray Emission from a Miniature Supernova Remnant

I present the data of the shell of classical Nova Persei (1901) obtained by the Advanced CCD Imaging Spectrometer S3 detector on-board \cha Observatory. The X-ray nebula is affected mostly by the complex interstellar medium around the nova and has not developed a regular shell with bulk of emission coming from the southwestern quadrant. The part of the bright zone that is co-spatial with the brightest non-thermal radio emission region, is found to be a source of non-thermal X-ray emission with a power law photon index of 2.3$^{+1.5}_{-0.9}$ and alpha=0.68^${+0.03}_{-0.15}$ at about a flux of 1.7x10^{-13} erg cm^{-2} s^{-1}. There are strong indications for nonlinear diffusive shock acceleration occurring in the forward shock/transition zone with an upper limit on the non-thermal X-ray flux of 1.0\times 10^{-14} erg cm^{-2} s^{-1}.The total X-ray spectrum of has two components of emission. The component dominant below 2 keV is most likely a non-equilibrium ionization thermal plasma of kT_s=0.1-0.3 keV with an X-ray flux of 1.6x10^{-11} erg cm^{-2} s^{-1}. There is also a higher temperature, kT_s=0.5-2.6 keV, embedded, N_H=(4.0-22.0)x10^{22} cm^{-2}, emission component prominent above 2 keV. The unabsorbed X-ray flux from this component is 1.5x10^{-10} erg cm^{-2} s^{-1}. The X-ray emitting plasma is of solar composition except for enhancement in the elemental abundances (mean abundances over the remnant)of Ne/Ne$_{\odot}$ and N/N$_{\odot}$ in a range 13-21 and 1-5, respectively. A distinct emission line of neon, He-like Ne IX, is detected which reveals a distribution of several emission knots/blobs and shows a cone-like structure with wings extending toward NW and SE at expansion velocities about 2600 km s^{-1} in the X-rays.

astro-ph↗