Swift observations of two supergiant fast X-ray transient prototypes in outburst

被引:20
作者
Farinelli, R. [1 ,2 ]
Romano, P. [2 ]
Mangano, V. [2 ]
Ceccobello, C. [1 ]
Ducci, L. [3 ]
Vercellone, S. [2 ]
Esposito, P. [4 ]
Kennea, J. A. [5 ]
Burrows, D. N. [5 ]
机构
[1] Univ Ferrara, Dipartimento Fis, I-44122 Ferrara, Italy
[2] Ist Astrofis Spaziale & Fis Cosm, INAF, I-90146 Palermo, Italy
[3] Univ Tubingen, Inst Astron & Astrophys, D-72076 Tubingen, Germany
[4] Osservatorio Astron Cagliari, INAF, I-09012 Capoterra, Italy
[5] Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA
关键词
X-rays: binaries; X-rays: individual: XTE J1739-302; X-rays: individual: IGR J17544-2619; XTE J1739-302; IGR J17544-2619; NEUTRON-STAR; ORBITAL PERIOD; O-STARS; ACCRETION; BINARIES; WINDS; TELESCOPE; DISCOVERY;
D O I
10.1111/j.1365-2966.2012.21422.x
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We report on the results from observations of the most recent outbursts of XTE J1739-302 and IGR J17544-2619, which are considered to be the prototypes of the supergiant fast X-ray transient class. They triggered the Swift/Burst Alert Telescope on 2011 February 22 and March 24, respectively, and each time a prompt Swift slew allowed us to obtain the rich broad-band data we present. The X-ray Telescope light curves show the descending portion of very bright flares that reached luminosities of similar to 2 x1036 and similar to 5 x 1036?erg?s-1. The broad-band spectra, when fitted with the usual phenomenological models adopted for accreting neutron stars, yield values of both high-energy cut-off and e-folding energy consistent with those obtained from previously reported outbursts from these sources. In the context of more physical models, the spectra of both sources can be well fitted either with a two-blackbody model or with a single unsaturated Comptonization model. In the latter case, the model can be either a classical static Comptonization model, such as COMPTT, or the recently developed COMPMAG model, which includes thermal and bulk Comptonization for cylindrical accretion on to a magnetized neutron star. We discuss the possible accretion scenarios derived by the different models, and we also emphasize the fact that the electron density derived from the Comptonization models, in the regions where the X-ray spectrum presumably forms, is lower than that estimated using the continuity equation at the magnetospheric radius and the source X-ray luminosity, and we give some possible explanations.
引用
收藏
页码:2854 / 2863
页数:10
相关论文
共 45 条
[1]   The burst alert telescope (BAT) on the Swift MIDEX mission [J].
Barthelmy, SD ;
Barbier, LM ;
Cummings, JR ;
Fenimore, EE ;
Gehrels, N ;
Hullinger, D ;
Krimm, HA ;
Markwardt, CB ;
Palmer, DM ;
Parsons, A ;
Sato, G ;
Suzuki, M ;
Takahashi, T ;
Tashiro, M ;
Tueller, J .
SPACE SCIENCE REVIEWS, 2005, 120 (3-4) :143-164
[2]   Thermal and bulk comptonization in accretion-powered X-ray pulsars [J].
Becker, Peter A. ;
Wolff, Michael T. .
ASTROPHYSICAL JOURNAL, 2007, 654 (01) :435-457
[3]   INTEGRAL long-term monitoring of the supergiant fast X-ray transient XTE J1739-302 [J].
Blay, P. ;
Martinez-Nunez, S. ;
Negueruela, I. ;
Pottschmidt, K. ;
Smith, D. M. ;
Torrejon, J. M. ;
Reig, P. ;
Kretschmar, P. ;
Kreykenbohm, I. .
ASTRONOMY & ASTROPHYSICS, 2008, 489 (02) :669-676
[4]   Are there magnetars in high-mass x-ray binaries? The case of supergiant fast X-ray transients [J].
Bozzo, E. ;
Falanga, M. ;
Stella, L. .
ASTROPHYSICAL JOURNAL, 2008, 683 (02) :1031-1044
[5]   The supergiant fast X-ray transients XTE J1739-302 and IGRJ08408-4503 in quiescence with XMM-Newton [J].
Bozzo, E. ;
Stella, L. ;
Ferrigno, C. ;
Giunta, A. ;
Falanga, M. ;
Campana, S. ;
Israel, G. ;
Leyder, J. C. .
ASTRONOMY & ASTROPHYSICS, 2010, 519
[6]   The Swift X-ray telescope [J].
Burrows, DN ;
Hill, JE ;
Nousek, JA ;
Kennea, JA ;
Wells, A ;
Osborne, JP ;
Abbey, AF ;
Beardmore, A ;
Mukerjee, K ;
Short, ADT ;
Chincarini, G ;
Campana, S ;
Citterio, O ;
Moretti, A ;
Pagani, C ;
Tagliaferri, G ;
Giommi, P ;
Capalbi, M ;
Tamburelli, F ;
Angelini, L ;
Cusumano, G ;
Bräuninger, HW ;
Burkert, W ;
Hartner, GD .
SPACE SCIENCE REVIEWS, 2005, 120 (3-4) :165-195
[7]  
CASH W, 1979, ASTROPHYS J, V228, P939, DOI 10.1086/156922
[8]   Discovery of the orbital period in the supergiant fast X-ray transient IGR J17544-2619 [J].
Clark, D. J. ;
Hill, A. B. ;
Bird, A. J. ;
McBride, V. A. ;
Scaringi, S. ;
Dean, A. J. .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2009, 399 (01) :L113-L117
[9]   THE 3 TYPES OF HIGH-MASS X-RAY PULSATOR [J].
CORBET, RHD .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 1986, 220 (04) :1047-1056
[10]   NEUTRON-STAR ACCRETION IN A STELLAR WIND - MODEL FOR A PULSED X-RAY SOURCE [J].
DAVIDSON, K ;
OSTRIKER, JP .
ASTROPHYSICAL JOURNAL, 1973, 179 (02) :585-598