EDP Sciences
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Volume 404, Number 1, June II 2003
Page(s) 163 - 170
Section Stellar clusters and associations
DOI http://dx.doi.org/10.1051/0004-6361:20030393

A&A 404, 163-170 (2003)
DOI: 10.1051/0004-6361:20030393

On the distribution of EGRET unidentified sources in the Galactic plane

D. Bhattacharya1, 2, A. Akyüz3, T. Miyagi1, J. Samimi4 and A. Zych1

1  Institute of Geophysics and Planetary Physics, University of California, Riverside, CA 92521, USA
2  Riverside Community College, Riverside, CA 92506, USA
3  Dept. of Physics, Cukurova University, Adana, Turkey
4  Dept. pf Physics, Sharif University of Technology, Tehran, Iran

(Received 16 September 2002 / Accepted 10 March 2003)

It has been suggested that young pulsars, with ages less than a million years, are possible counterparts of some of the Galactic unidentified gamma-ray sources detected by the EGRET instrument on-board the Compton Gamma Ray Observatory. In this work, we compare different aspects of the EGRET unidentified (EUI) source distribution in the Galactic plane with those of the pulsar distribution. An EUI source Log N-Log S analysis is presented and compared with the Galactic radio pulsar Log N-Log S distribution. A number of systematic effects that could introduce errors to the EGRET Log N-Log S relation are discussed. A two-point angular correlation analysis of the EUI sources and Galactic pulsars is performed. We find that the global distribution properties of the plane EUI sources do not follow those of the young pulsar population. We conclude that even though a fraction of the EUI sources may have young pulsar counterparts, the majority of them follow a distribution that is similar to the molecular cloud distribution in nearby spiral arms.

Key words: gamma rays: observations -- stars: pulsars: general -- ISM: clouds

Offprint request: D. Bhattacharya, dipen@tigre.ucr.edu

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