NuSTAR Observations of the Accreting Atolls GX 3+1, 4U 1702-429, 4U 0614+091, and 4U 1746-371

Journal article


Publication Details

Author(s): Ludlam RM, Miller JM, Barret D, Cackett EM, Coughenour BM, Dauser T, Degenaar N, Garcia J, Harrison FA, Paerels F
Journal: Astrophysical Journal
Publication year: 2019
Volume: 873
Journal issue: 1
ISSN: 0004-637X


Abstract

Atoll sources are accreting neutron star (NS) low-mass X-ray binaries. We present a spectral analysis of four persistent atoll sources (GX 3+1, 4U 1702-429, 4U 0614+091, and 4U 1746-371) observed for similar to 20 ks each with NuSTAR to determine the extent of the inner accretion disk. These sources range from an apparent luminosity of 0.006-0.11 of the Eddington limit (assuming the empirical limit of 3.8 x 10(38) erg s(-1)). Broad Fe emission features shaped by Doppler and relativistic effects close to the NS were firmly detected in three of these sources. The position of the disk appears to be close to the innermost stable circular orbit (ISCO) in each case. For GX 3+1, we determine = R-in = 1.8(-0.6)(+0.2) R-ISCO (90% confidence level) and an inclination of 27 degrees-31 degrees. For 4U 1702-429, we find a = R-in = 1.5(-0.4)(+1.6) R-ISCO and inclination of 53 degrees-64 degrees. For 4U 0614+ 091, the disk has a position of R-in = 1.3(-0.2)(+5.4) ISCO and inclination of 50 degrees-62 degrees. If the disk does not extend to the innermost stable circular orbit, we can place conservative limits on the magnetic field strength in these systems in the event that the disk is truncated at the Alfven radius. This provides the limit at the poles of B <= 6.7 x 10(8) G, 3.3. x. 10(8) G, and 14.5. x. 10(8) G for GX 3+1, 4U. 1702-429, and 4U 0614+091, respectively. For 4U 1746-371, we argue that the most plausible explanation for the lack of reflection features is a combination of source geometry and strong Comptonization. We place these sources among the larger sample of NSs that have been observed with NuSTAR.


FAU Authors / FAU Editors

Dauser, Thomas Dr.
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Garcia, Javier Dr.
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut


External institutions with authors

California Institute of Technology (Caltech)
Columbia University
University of Amsterdam
University of Michigan
University of Toulouse
Wayne State University (WSU)


How to cite

APA:
Ludlam, R.M., Miller, J.M., Barret, D., Cackett, E.M., Coughenour, B.M., Dauser, T.,... Paerels, F. (2019). NuSTAR Observations of the Accreting Atolls GX 3+1, 4U 1702-429, 4U 0614+091, and 4U 1746-371. Astrophysical Journal, 873(1). https://dx.doi.org/10.3847/1538-4357/ab0414

MLA:
Ludlam, R. M., et al. "NuSTAR Observations of the Accreting Atolls GX 3+1, 4U 1702-429, 4U 0614+091, and 4U 1746-371." Astrophysical Journal 873.1 (2019).

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Last updated on 2019-22-03 at 08:08