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Searching for old neutron stars with ROSAT. II. Soft X-ray sources in galactic dark clouds

Danner, R. (1998) Searching for old neutron stars with ROSAT. II. Soft X-ray sources in galactic dark clouds. Astronomy and Astrophysics Supplement Series, 128 (2). pp. 349-357. ISSN 0365-0138. doi:10.1051/aas:1998384.

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This is the second in a series of three papers constraining the number of detectable old neutron stars in the Galaxy. Here, I present the statistical analysis of a sample of X-ray sources coincident with areas of dark clouds in the Galactic plane. I compare this sample with all sources in the ROSAT All-Sky Survey bright source catalog within 20° of the Galactic plane. I present the results of an identification program of a subset of sources that are compatible with a soft, thermal X-ray spectrum and an effective source temperature of less than 70 eV. The three brightest sources in this sample form an intriguing subgroup. One of them is a previously identified candidate for an accreting neutron star. I identify the other two sources with hot white dwarf stars. I find no new accreting neutron star candidate in this sample. Based on this result, I derive an upper limit to the space density of accreting neutron stars in fields of Galactic dark clouds of ~ 2 sr^(-1) at a count rate > 0.05 s^(-1).

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Additional Information:© European Southern Observatory (ESO), 1998. Received December 16, 1996; accepted August 1, 1997. This article is based on research conducted during my three year visit to the California Institute of Technology. I want to thank Prof. S.R. Kulkarni for his hospitality, support and countless discussions during this time. I am indebt to J. Trümper for his support of this project and many fruitful suggestions. I thank Chris Clemens and Angela Putney for help with understanding the blue spectrum. The ROSAT project is supported by the German Bundesministerium für Bildung und Wissenschaft (BMBW/DARA) and the Max-Planck-Society. This research has made use of the NASA/IPAC extragalactic database NED) which is operated by the Jet Propulsion Laboratory, Caltech, under contract with the National Aeronautics and Space Administration, and of the SIMBAD database, operated at CDS, Strasbourg, France. The Digitized Sky Survey (DSS) was produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166.
Group:Infrared Processing and Analysis Center (IPAC)
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Bundesministerium für Bildung und Wissenschaft (BMBW)UNSPECIFIED
Subject Keywords:surveys / X-rays: stars / stars: neutron; white dwarfs
Issue or Number:2
Record Number:CaltechAUTHORS:20180507-141344492
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Official Citation:Searching for old neutron stars with ROSAT - II. Soft X-ray sources in galactic dark clouds R. Danner Astron. Astrophys. Suppl. Ser., 128 2 (1998) 349-357 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86252
Deposited By: George Porter
Deposited On:08 May 2018 14:39
Last Modified:15 Nov 2021 20:36

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