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Titolo:
A measurement of the broadband spectrum of XTE J1118+480 with BeppoSAX andits astrophysical implications
Autore:
Frontera, F; Zdziarski, AA; Amati, L; Mikolajewska, J; Belloni, T; Del Sordo, S; Haardt, F; Kuulkers, E; Masetti, N; Orlandini, M; Palazzi, E; Parmar, AN; Remillard, RA; Santangelo, A; Stella, L;
Indirizzi:
Univ Ferrara, Dipartimento Fis, I-44100 Ferrara, Italy Univ Ferrara Ferrara Italy I-44100 artimento Fis, I-44100 Ferrara, Italy CNR, Ist Tecnol & Studio Radiaz Extraterr, I-40129 Bologna, Italy CNR Bologna Italy I-40129 tudio Radiaz Extraterr, I-40129 Bologna, Italy Nicholas Copernicus Astron Ctr, PL-00716 Warsaw, Poland Nicholas Copernicus Astron Ctr Warsaw Poland PL-00716 716 Warsaw, Poland Osserv Astron Brera, I-23807 Merate, Italy Osserv Astron Brera Merate Italy I-23807 on Brera, I-23807 Merate, Italy CNR, Ist Fis Cosm & Applicaz Informat, I-90146 Palermo, Italy CNR Palermo Italy I-90146 sm & Applicaz Informat, I-90146 Palermo, Italy Univ Insubria, I-22100 Como, Italy Univ Insubria Como Italy I-22100Univ Insubria, I-22100 Como, Italy Space Res Org Netherlands, NL-3584 CA Utrecht, Netherlands Space Res Org Netherlands Utrecht Netherlands NL-3584 CA ht, Netherlands Univ Utrecht, Astron Inst, NL-3504 TA Utrecht, Netherlands Univ Utrecht Utrecht Netherlands NL-3504 TA 3504 TA Utrecht, Netherlands European Space Agcy, Dept Space Sci, Div Astrophys, NL-2200 AG Noordwijk, Netherlands European Space Agcy Noordwijk Netherlands NL-2200 AG rdwijk, Netherlands MIT, Ctr Space Res, Cambridge, MA 02139 USA MIT Cambridge MA USA 02139MIT, Ctr Space Res, Cambridge, MA 02139 USA MIT, Dept Phys, Cambridge, MA 02139 USA MIT Cambridge MA USA 02139MIT, Dept Phys, Cambridge, MA 02139 USA Osserv Astron Roma, I-00040 Monteporzio Catone, Italy Osserv Astron Roma Monteporzio Catone Italy I-00040 porzio Catone, Italy
Titolo Testata:
ASTROPHYSICAL JOURNAL
fascicolo: 2, volume: 561, anno: 2001,
parte:, 1
pagine: 1006 - 1015
SICI:
0004-637X(20011110)561:2<1006:AMOTBS>2.0.ZU;2-D
Fonte:
ISI
Lingua:
ENG
Soggetto:
X-RAY TRANSIENT; ASTRONOMY SATELLITE; CYGNUS X-1; ON-BOARD; H-I; RADIATION; GALAXY; STATE; COMPTONIZATION; DISCOVERY;
Keywords:
accretion, accretion disks; binaries : general; lack hole physics; stars : individual (XTE J1118+480); X-rays : individual (XTE J1118+480); X-rays : stars;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
58
Recensione:
Indirizzi per estratti:
Indirizzo: Frontera, F Univ Ferrara, Dipartimento Fis, Via Paradiso 12, I-44100 Ferrara, Italy Univ Ferrara Via Paradiso 12 Ferrara Italy I-44100 ara, Italy
Citazione:
F. Frontera et al., "A measurement of the broadband spectrum of XTE J1118+480 with BeppoSAX andits astrophysical implications", ASTROPHYS J, 561(2), 2001, pp. 1006-1015

Abstract

We report on results of a Target-of-Opportunity observation of the X-ray transient XTE J1118+480 performed on 2000 April 14-15 with the Narrow Field Instruments (0.1-200 keV) of the BeppoSAX satellite. The measured spectrum is a power law with a photon index of similar to1.7 modified by an ultrasoft X-ray excess and a high-energy cutoff above similar to 100 keV. The soft excess is consistent with a blackbody with a temperature of similar to 40 eV and a low flux, while the cutoff power law is well fitted by thermal Comptonization in a plasma with an electron temperature of similar to 10(2) keVand an optical depth of order unity. Consistent with the weakness of the blackbody, Compton reflection is weak. Although the data are consistent withvarious geometries of the hot and cold phases of the accreting gas, we conclude that a hot accretion disk is the most plausible model. The Eddington ratio implied by recent estimates of the mass and the distance is similar to 10(-3), which may indicate that advection is probably not the dominant cooling mechanism. We finally suggest that the reflecting medium has a low metallicity, consistent with the location of the system in the halo.

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Documento generato il 26/09/17 alle ore 09:27:05