相关论文: Supersoft X-ray Sources in M31: I. A Chandra Surve…

A Chandra ACIS-S imaging observation of the nearby galaxy M81 (NGC 3031) reveals 9 luminous soft X-ray sources. The local environments, X-ray spectral properties, and X-ray light curves of the sources are presented and discussed in the…

We introduce a procedure to identify very soft X-ray sources (VSSs) in external galaxies. Our immediate goal was to formulate a systematic procedure to identify luminous supersoft X-ray sources (SSSs), so as to allow comparisons among…

Chandra observations of nearby galaxies have revealed a number of X-ray sources characterized by high luminosities ($L_X > \sim10^{36}$ erg s$^{-1}$) and $k T$ in the range $100 - 350$ eV. These ``quasisoft X-ray sources'' (QSSs) are harder…

The deepest X-ray images of M31, obtained with XMM-Newton, are examined in this paper to derive spectral and statistical properties of the population of the softest X-ray sources. Classifying supersoft X-ray sources (SSS) with criteria…

We have performed Chandra observations during the past 3 years of 5 of the M31 supersoft X-ray sources (SSS) discovered with ROSAT. Surprisingly, only one of these sources has been detected, despite a predicted detection of about 20-80…

We apply a uniform procedure to select very soft sources from point sources observed by Chandra in 4 galaxies. This sample includes one elliptical galaxy (NGC 4967), 2 face-on spirals (M101 and M83), and an interacting galaxy (M51). We have…

To investigate the transient nature of supersoft sources (SSSs) in M 31, we compared SSS candidates of the XMM-Newton Deep Survey, ROSAT PSPC surveys and the Chandra catalogues in the same field. We found 40 SSSs in the XMM-Newton…

We report on possible associations between 6 globular clusters in the Virgo elliptical galaxy NGC 4472 (M49) and bright ($L_x > 10^{38}$ erg s$^{-1}$) very soft X-ray sources (VSSs). Two of the VSSs have broad-band spectral properties…

We report on observations of a luminous supersoft X-ray source (SSS) in M31, r1-25, that has exhibited spectral changes to harder X-ray states. We document these spectral changes. In addition, we show that they have important implications…

We use a set of conservative criteria to identify luminous supersoft X-ray sources(SSSs) in external galaxies. We test this approach on blackbody models, and then apply it to {\it Chandra} data from 4 galaxies: an elliptical (NGC 4967), 2…

First discovered in the Magellanic Clouds and in the Milky Way, the largest pools of luminous supersoft X-ray sources (SSSs) now known lie in M31 and in more distant galaxies. Hundreds of newly-discovered SSSs are helping us to test models…

The 1991 ROSAT PSPC M31 X-ray point source catalog has been screened in order to set up a sample of candidate supersoft sources in this galaxy, additional to the 16 supersoft sources of Supper et al. (1997). 26 candidates have been found.…

This study represents the most sensitive Chandra X-ray point source catalogue of M31. Using 133 publicly available Chandra ACIS-I/S observations totalling ~1 Ms, we detected 795 X-ray sources in the bulge, northeast, and southwest fields of…

We report on \chandra observations of the central region of M31. By combining eight \chandra ACIS-I observations taken between 1999 and 2001, we have identified 204 X-ray sources within the central $\sim 17'\times17'$ region of M31, with a…

The first supersoft source (SSS) identification with an optical nova in M 31 was based on ROSAT observations. Twenty additional X-ray counterparts (mostly identified as SSS by their hardness ratios) were detected using archival ROSAT,…

Classical novae (CNe) have recently been reported to represent the major class of supersoft X-ray sources (SSSs) in the central area of our neighbouring galaxy M 31. This paper presents a review of results from recent X-ray observations of…

We study populations of soft and super-soft X-ray sources in nearby galaxies of various morphological types with the special emphasis on characterizing populations of stable nuclear burning accreting WDs. Analysing the content of Chandra…

Novae undergo a supersoft X-ray phase of varying duration after the optical outburst. Such transient post-nova supersoft X-ray sources (SSSs) are the majority of the observed SSSs in M31. In this paper, we use the post-nova evolutionary…

Luminous supersoft X-ray sources found in the Milky Way and Magellanic Clouds are likely white dwarfs that steadily or cyclically burn accreted matter on their surface, which are promising type Ia supernova progenitors. Observations of…

We carried out new observations of two fields in the northern ring of M31 with XMM-Newton with two exposures of 100 ks each and obtained a complete list of X-ray sources down to a sensitivity limit of ~7 x 10^34 erg s^-1 (0.5 - 2.0 keV).…