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.Comment: 56 pages and 16 figures; Accepted to be published in the Astrophysical Journal (Part 1) as it stand

X-ray properties of dwarf nova EY Cyg and the companion star using an XMM-Newton observation

We present the X-ray analysis of dwarf nova EY Cyg using the 45 ks \textit{XMM-Newton} observatory archival data obtained in quiescence. We find orbital modulations in X-rays. We simultaneously fitted EPIC pn, MOS1 and MOS2 data using a model for interstellar medium absorption (\textit{tbabs}) and a multi-temperature plasma emission model with a power-law distribution of temperatures (CEVMKL) as expected from low accretion rate quiescent dwarf novae. The \textit{XMM-Newton} EPIC spectra of the source yields a maximum temperature $kT_{\rm max}$ $\sim$ 14.9$^{+3.3}_{-2.2}$ keV with an unabsorbed X-ray flux and luminosity of (1.8--2.0) $\times$ 10$^{-12}$ ergs$^{-1}$ cm$^{-1}$ and (8.7--9.7) $\times$ 10$^{31}$ ergs$^{-1}$, respectively, in the energy range 0.1 to 50 keV. There is 3--4 sigma excess at energies below 0.5 keV, we model the excess using \textit{MEKAL}, POWERLAW and BBODY models and favor the model \textit{MEKAL} which is physical. According to previous studies, the secondary in this system is thought to be a K-type star which may radiate in the soft X-ray region. The fit with an additive \textit{MEKAL} model gives a temperature of $kT$ $\sim$ 0.1 keV with an unabsorbed X-ray flux and luminosity of (2.7--8.8) $\times$ 10$^{-14}$ ergs$^{-1}$ cm$^{-1}$ and (1.3--4.2) $\times$ 10$^{30}$ ergs$^{-1}$, respectively, for the companion star. Based on the results from the timing and spectral analysis, we highly suggest that the secondary of EY Cyg is a K-type star.Comment: 7 pages, 3 figures, 3 tables. Accepted for publication in a Special Issue of Advances in Space Research, entitled "Nova Eruptions, Cataclysmic Variables and Related Systems: observational vs theoretical challenges in the 2020 era", edited BY S. Balman and P. A. She

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.Comment: 6 pages, 3 figures, To appear in ApJ 01 May 2006 issu

The inclination angle 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 H- and Ks-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 those of a K7 V, 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 degrees ±2 degrees. This inclination angle corresponds to a primary black hole mass of 8.53+/-0.60 M☉. 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