Probing the MSP Prenatal Stage: The Optical Identification of the X-Ray Burster EXO 1745-248 in Terzan 5

Journal
Date Issued
2015
Author(s)
Ferraro, F. R.
•
Pallanca, C.
•
Lanzoni, B.
•
Cadelano, M.
•
Massari, D.
•
•
Mucciarelli, A.
DOI
Abstract
We report on the optical identification of the neutron star burster EXO 1745-248 in Terzan 5. The identification was performed by exploiting Hubble Space Telescope/Advanced Camera for Surveys images acquired in Director's Discretionary Time shortly after (approximately one month) the Swift detection of the X-ray burst. The comparison between these images and previous archival data revealed the presence of a star that is currently brightened by ∼3 mag, consistent with expectations during an X-ray outburst. The centroid of this object well agrees with the position, in the archival images, of a star located in the turn-off/sub-giant-branch region of Terzan 5. This supports the scenario that the companion should have recently filled its Roche Lobe. Such a system represents the prenatal stage of a millisecond pulsar, an evolutionary phase during which heavy mass accretion on the compact object occurs, thus producing X-ray outbursts and re-accelerating the neutron star.

Based on observations (GO 14061, GO 12933, GO 9799) with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

Volume
807
Issue
1
Start page
L1
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2015ApJ...807L...1F
Rights
open.access
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