Jonker, P. G., Campana, S., Steeghs, D., Torres, M. A. P., Galloway, D. K., Markwardt, C. B., Chakrabarty, Deepto and Swank, Jean H. (2005) Chandra observations of the millisecond X-ray pulsar IGR J00291+5934 in quiescence. Monthly Notices of the Royal Astronomical Society, Vol.361 (No.2). pp. 511-516. doi:10.1111/j.1365-2966.2005.09171.x ISSN 0035-8711.

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Abstract

In this paper we report on our analysis of three Chandra observations of the accretion-powered millisecond X-ray pulsar IGR J00291+5934 obtained during the late stages of the 2004 outburst. We also report the serendipitous detection of the source in quiescence by ROSAT during MJD 48830–48839 (1992 July 26–August 4). The detected 0.3–10 keV source count rates varied significantly between the Chandra observations from (7.2 ± 1.2) × 10−3, (6.8 ± 0.9) × 10−3 and (1.4 ± 0.1) × 10−2 counts s−1 for the first, second and third Chandra observations, on MJD 53371.88 (2005 January 1), 53383.99 (2005 January 13) and 53407.57 (2005 February 6), respectively. The count rate for the third observation is 2.0 ± 0.4 times as high as that of the average of the first two observations. The unabsorbed 0.5–10 keV source fluxes for the best-fitting power-law model to the source spectrum were (7.9 ± 2.5) × 10−14, (7.3 ± 2.0) × 10−14, and (1.17 ± 0.22) × 10−13 erg cm−2 s−1 for the first, second and third Chandra observations, respectively. We find that this source flux is consistent with that found by ROSAT[≈(5.4 ± 2.4) × 10−14 erg cm−2 s−1]. Under the assumption that the interstellar extinction, NH, does not vary between the observations, we find that the blackbody temperature during the second Chandra observation is significantly higher than that during the first and third observations. Furthermore, the effective temperature of the neutron star derived from fitting an absorbed blackbody or neutron star atmosphere model to the data is rather high in comparison with many other neutron star soft X-ray transients in quiescence, even during the first and third observations. If we assume that the source quiescent luminosity is similar to that measured for two other accretion powered millisecond pulsars in quiescence, the distance to IGR J00291+5934 is 2.6–3.6 kpc.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science, Engineering and Medicine > Science > Physics
Library of Congress Subject Headings (LCSH):	Pulsars
Journal or Publication Title:	Monthly Notices of the Royal Astronomical Society
Publisher:	Wiley
ISSN:	0035-8711
Official Date:	2005
Dates:	Date Event 2005 Published
Volume:	Vol.361
Number:	No.2
Page Range:	pp. 511-516
DOI:	10.1111/j.1365-2966.2005.09171.x
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Date of first compliant deposit:	22 December 2015
Date of first compliant Open Access:	22 December 2015
Funder:	United States. National Aeronautics and Space Administration (NASA), Smithsonian Astrophysical Observatory
Grant number:	PF3–40027 (NASA), GO4-5033X (NASA)

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