Issue |
A&A
Volume 690, October 2024
|
|
---|---|---|
Article Number | A330 | |
Number of page(s) | 9 | |
Section | Galactic structure, stellar clusters and populations | |
DOI | https://doi.org/10.1051/0004-6361/202449473 | |
Published online | 18 October 2024 |
Multiwavelength identification of millisecond pulsar candidates in the Galactic bulge
1
LAPTh, CNRS, USMB, 74940
Annecy, France
2
Université Grenoble Alpes, CNRS, IPAG, 38000
Grenoble, France
3
University of Maryland, Department of Astronomy, College Park, MD, 20742
USA
4
NASA Goddard Space Flight Center, Code 662, Greenbelt, MD, 20771
USA
5
National Radio Astronomy Observatory, PO Box O
Socorro, NM, 87801
USA
6
Dept. of Engineering & Physics, Sweet Briar College, Sweet Briar, VA, 24595
USA
7
Space Science Division, US Naval Research Laboratory, Washington, DC, 20375
USA
Received:
2
February
2024
Accepted:
22
March
2024
Context. The existence of a population of millisecond pulsars in the Galactic bulge is supported, along with other evidence, by the Fermi GeV excess, an anomalous γ-ray emission detected almost 15 years ago in the direction of the Galactic center. However, radio surveys searching for pulsations have not yet revealed bulge millisecond pulsars.
Aims. Identifying promising bulge millisecond pulsar candidates is key to motivating pointed radio pulsation searches. Candidates are often selected among steep-spectrum or polarized radio sources, but multiwavelength information can also be exploited: The aim of this work is to pinpoint strong candidates among the yet unidentified X-ray sources.
Methods. We investigated the multiwavelength counterparts of sources detected by the Chandra X-ray observatory that have spectral properties expected for millisecond pulsars in the Galactic bulge. We considered that ultraviolet, optical, and strong infrared counterparts indicate that an X-ray source is not a bulge pulsar, while a radio or a faint infrared counterpart makes it a promising candidate.
Results. We identify a large population of more than a thousand X-ray sources without optical, ultraviolet, or strong infrared counterparts. Among them, five are seen for the first time in unpublished radio imaging data from the Very Large Array. We provide the list of promising candidates, for most of which follow-up pulsation searches are ongoing.
Key words: pulsars: general / Galaxy: bulge / radio continuum: stars / X-rays: stars
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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