2003/11/17 by I. Harrus, Ilana M. Harrus, Patrick O. Slane +3 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Cosmic Phenomena #Pulsars and Gravitational Waves Research #astro-ph
paper · pdf · doi:10.1086/381355
published as Astrophys.J. 603 (2004) 152-158 · 17 pages, 4 figures, Accepted for publication in ApJ. Vol 603 March 1 issue
arxiv created 2003/11/17 · openalex publication_date 2004/02/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present an analysis of data from both the Röntgen Satellite ( ROSAT ) and the Advanced Satellite for Cosmology and Astrophysics ( ASCA ) of the supernova remnant G18.95-1.1. We find that the X-ray emission from G18.95-1.1 is predominantly thermal, heavily absorbed with a column density around 10 22 atoms cm -2 , and can be best described by an nonequilibrium ionization (NEI) model with a temperature around 0.9 keV and an ionization timescale of 1.1 × 10 10 cm -3 s -1 . We find only marginal evidence for nonsolar abundances. Comparisons between 21 cm H I absorption data and derived parameters from our spectral analysis strongly suggest a relatively nearby remnant (a distance of about 2 kpc). Above 4 keV, we identify a small region of emission located at the tip of the central, flat-spectrum barlike feature in the radio image. We examine two possibilities for this emission region: a temperature variation within the remnant or a pulsar wind nebula (PWN). The current data do not allow us to distinguish between these possible explanations. In the scenario where this high-energy emission region corresponds to a PWN, our analysis suggests a rotational loss rate for the unseen pulsar of about 7 × 10 35 ergs s -1 and a ratio L r / L X of about 3.6 for the entire PWN, slightly above the maximum ratio (3.4 for Vela) measured in known PWNe.