Published in:

Astrophysical Journal Letters 652,2 (2006) L109-L112;

Abstract

We present high-resolution X-ray images taken with the Chandra X-Ray Observatory of the field that contains the unidentified TeV gamma-ray source HESS J1804-216. A total of 11 discrete sources were detected with a posteriori significance of > 5 sigma over the entire field of view. Among them, only one, designated as CXOU J180351.4-213707, is significantly extended. The source is about 40" away from the radio pulsar PSR J1803-2137, which was the target of the Chandra observation but was not detected in X-rays. A natural question is whether the two sources are physically related. While it is conceivable that CXOU J180351.4-213707 could be associated with a previously unknown supernova remnant (SNR), in which the pulsar was born, it seems equally plausible that it might be a pulsar wind nebula (PWN) that is powered by a different pulsar whose emission is beamed away from us. In either case, we argue that CXOU J180351.4-213707 is likely the X-ray counterpart of HESS J1804-216, based on the fact that the Galactic TeV gamma-ray sources are predominantly SNRs or PWNe. The X-ray spectrum of the source can be well fitted with a power law, although the model is not well constrained due to large statistical uncertainties. The spectrum seems to be very hard, with a best-fit photon index of about 1.2. Under the assumption that CXOU J180351.4-213707 is the X-ray counterpart of HESS J1804-216, we attempted to model the X-ray and TeV emission as synchrotron and inverse Compton scattered radiation from relativistic electrons. We briefly discuss the results.

Keywords

acceleration of particles;; gamma rays : theory;; pulsars : individual (psr j1803-2137);; radiation mechanisms : nonthermal;; supernova remnants;; x-rays : general;; supernova-remnants;; synchrotron nebula;; vela pulsar;; association;; discovery

Date of this Version

January 2006

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.