The Nature of the Compact X-Ray Source in the Supernova Remnant G27.4+0.0
Abstract
High-resolution X-ray imaging data obtained with ROSAT is used to constrain the nature of the central compact source in the supernova remnant G27.4+0.0. Diffuse emission is seen from throughout the approximately 4 min diameter radio shell, while the central source remains unresolved at approximately 3 sec. We combine archival data from the Einstein HRI, IPC, and MPC with the ROSAT HRI data to define the X-ray spectra of the diffuse and point-like emission. The bulk of the shell radiation is consistent with that of a approximately 107 K plasma, although a higher temperature component is also suggested by the data; coupled with the remnant's size and distance, we derive an age of between 500 and 2500 yr. The point source has a substantially harder spectrum, with a power-law photon index less than or approximately equal to 1. A search for periodic modulation from the point source yields upper limits ranging from 10%-35% for periods between 0.025 and 1000 s, depending on the assumed pulse shape. No aperiodic variability on timescales of from 103 to 108 s is required, although a factor of approximately 2 change between the Einstein and ROSAT eras is possible. We show that the point source cannot represent thermal emission from the surface of a young neutron star and is unlikely to be explained as nonthermal, Crab-like X-ray pulses or a small synchrotron nebula. The most likely models involve accretion-powered systems -- either a wind-fed neutron star with a massive companion or a low-mass X-ray binary. In all probability, this is the youngest X-ray binary in the Galaxy.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1994
- DOI:
- 10.1086/174764
- Bibcode:
- 1994ApJ...434..627H
- Keywords:
-
- Astronomical Models;
- Neutron Stars;
- Radio Sources (Astronomy);
- Supernova Remnants;
- X Ray Astronomy;
- X Ray Binaries;
- X Ray Spectra;
- Heao 2;
- Rosat Mission;
- Stellar Winds;
- Very Large Array (Vla);
- X Ray Imagery;
- Astronomy;
- ISM: SUPERNOVA REMNANTS;
- ISM: INDIVIDUAL ALPHANUMERIC: G27.4;
- 0.0;
- RADIATION MECHANISMS: NONTHERMAL;
- X-RAYS: ISM