ROSAT HRI observations of the Local Group galaxies IC 10, NGC 147 and NGC 185

Abstract

We report on pointed X-ray observations of IC 10, NGC 147 and NGC 185 made with the ROSAT High Resolution Imager (HRI). These are three Local Group galaxies that have never been previously studied in detail in the X-ray regime. IC 10 is the closest starburst galaxy to our own Galaxy, and NGC 147 and NGC 185 are companions to M31. We have discovered a variable X-ray source coincident with IC 10. The source is located near the centre of a large, non-thermal bubble of radio emission, and it is positionally coincident with an emission line star in IC 10 which has been classified as a WN type Wolf-Rayet star. We demonstrate that a confusing foreground or background source is improbable. The X-ray source is probably an X-ray binary in IC 10, and it may be a Wolf-Rayet + black hole binary. The source has mean and maximum 0.1--2.5 keV isotropic luminosities of about 2 and 4 times 10^{38} erg/s. We do not detect any sources in the central regions of NGC 147 or NGC 185. We place upper limits on their central X-ray emission, and we list all X-ray sources coincident with their outer extents. We also present the first X-ray detections of the well-studied Algol-type binary TV Cas and the W UMa-type binary BH Cas, which were both serendipitously observed during our IC 10 pointing.

9 pages, uuencoded compressed tar file, MNRAS in press, also available from http://www.astro.psu.edu/users/niel/papers/papers.html

Cited by in corpus (25)

• Dwarf Galaxies of the Local Group
• On IC 10 X-1, the Most Massive Known Stellar-Mass Black Hole
• The Orbital Period of the Wolf-Rayet Binary IC 10 X-1; Dynamic Evidence that the Compact Object is a Black Hole
• Understanding Compact Object Formation and Natal Kicks. III. The case of Cygnus X-1
• An Optical Study of Stellar and Interstellar Environments of Seven Luminous and Ultraluminous X-Ray Sources
• IC10~X-1/NGC300~X-1: the very immediate progenitors of BH-BH binaries
• Chandra and HST Confirmation of the Luminous and Variable X-ray Source IC 10 X-1 as a Possible Wolf-Rayet, Black-Hole Binary
• The star formation history of the Local Group dwarf elliptical galaxy NGC 185: II. Gradients in the stellar population
• Understanding Compact Object Formation and Natal Kicks. IV. The case of IC 10 X-1
• Multiwavelength study of the nuclei of a volume-limited sample of galaxies I: X-ray observations
• An XMM-Newton and Chandra Study of the Starburst Galaxy IC 10
• Genetic-Algorithm-based Light Curve Optimization Applied to Observations of the W UMa star BH Cas
• A synchrotron superbubble in the IC 10 Galaxy: a hypernova remnant?
• Deep spectroscopy of the emission-line populations in NGC185
• A Study of the Evolution of the Close Binaries Cyg X-3, IC 10 X-1, NGC 300 X-1, SS 433, and M33 X-7 Using the "Scenario Machine"
• On the Spin of the Black Hole in IC 10 X-1
• An optical and X-ray study of the contact binary, BH Cassiopeiae
• A High-Resolution Radio Continuum Study Of The Dwarf Irregular Galaxy IC 10
• Wolf-Rayet stars, black holes and the first detected gravitational wave source
• The ionization mechanism of NGC 185: how to fake a Seyfert galaxy?
• Synchrotron superbubble in the galaxy IC10: the ionized gas structure, kinematics, and emission spectrum
• Probing the Stellar Wind of the Wolf-Rayet Star in IC 10 X-1
• The interstellar medium in Andromeda's dwarf spheroidal galaxies: II. Multi-phase gas content and ISM conditions
• Revealing the nature of central emission nebulae in the dwarf galaxy NGC 185
• Diagnosing the Properties and Evolutionary Fates of Black Hole and Wolf-Rayet X-ray Binaries as Potential Gravitational Wave Sources for the LIGO-Virgo-KAGRA Network