2005A&A...441L...1I


Query : 2005A&A...441L...1I

2005A&A...441L...1I - Astronomy and Astrophysics, volume 441, L1 (2005/10-1)

Chandra observation of the fast X-ray transient IGR J17544-2619: evidence for a neutron star?

IN'T ZAND J.J.M.

Abstract (from CDS):

IGR J17544-2619 belongs to a distinct group of at least seven fast X-ray transients that cannot readily be associated with nearby flare stars or pre-main sequence stars and most probably are X-ray binaries with wind accretion. Sofar, the nature of the accretor has been determined in only one case (SAX J1819.3-2525/V4641 Sgr). We carried out a 20ks Chandra ACIS-S observation of IGR J17544-2619 which shows the source in quiescence going into outburst. The Chandra position confirms the previous tentative identification of the optical counterpart, a blue O9Ib supergiant at 3 to 4kpc (Pellizza, Chaty & Negueruela, in prep.). This is the first detection of a fast X-ray transient in quiescence. The quiescent spectrum is very soft. The photon index of 5.9±1.2 (90% confidence error margin) is much softer than 6 quiescent black hole candidates that were observed with Chandra ACIS-S (Kong et al., 2002ApJ...570..277K; Tomsick et al., 2003ApJ...597L.133T). Assuming that a significant fraction of the quiescent photons comes from the accretor and not the donor star, we infer that the accretor probably is a neutron star. A fit to the quiescent spectrum of the neutron star atmosphere model developed by Pavlov et al. (1994A&A...289..837P) and Zavlin et al. (1996A&A...315..141Z) implies an unabsorbed quiescent 0.5-10 keV luminosity of (5.2±1.3)x1032erg/s. We speculate on the nature of the brief outbursts.

Abstract Copyright:

Journal keyword(s): X-rays: binaries - X-rays: transients - X-rays: individual: IGR J17544-2619

Simbad objects: 10

goto Full paper

goto View the references in ADS

Number of rows : 10
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 V* RS CVn RS* 13 10 36.9078781154 +35 56 05.587686902 8.57 8.51 7.93 7.7   F6IV+G8IV 693 0
2 * tau Sco * 16 35 52.9528530 -28 12 57.661515 1.55 2.56 2.81 2.93 3.18 B0.2V 871 0
3 2MASS J16463526-4507045 HXB 16 46 35.2592332854 -45 07 04.609816032   15.2       O9.5Ia 89 1
4 V* DY Dra RR* 17 17 55.9094489598 +57 39 59.674682692   17.4 17.55   17.05 ~ 8 0
5 AX J1739.1-3020 HXB 17 39 11.5521531365 -30 20 37.783172824     14.40 13.91   O8.5Iab(f) 145 1
6 2XMM J174906.8-273232 HXB 17 49 06.79 -27 32 32.4           B1-3 41 0
7 IGR J17544-2619 HXB 17 54 25.2724584579 -26 19 52.578788584   14.71 12.94 12.10 10.38 O9Ib 169 0
8 SAX J1818.6-1703 HXB 18 18 37.8990045305 -17 02 47.970872274     17.4 17.4   ~ 96 0
9 V* V4641 Sgr HXB 18 19 21.6342721789 -25 24 25.849323550     13.654   13.092 B9III 415 1
10 XTE J1901+014 XB* 19 01 40.2 +01 26 31           ~ 52 1

To bookmark this query, right click on this link: simbad:objects in 2005A&A...441L...1I and select 'bookmark this link' or equivalent in the popup menu


2021.09.19-23:21:22

© Université de Strasbourg/CNRS

    • Contact