2005A&A...434...25F


C.D.S. - SIMBAD4 rel 1.7 - 2020.11.25CET10:37:02

2005A&A...434...25F - Astronomy and Astrophysics, volume 434, 25-34 (2005/4-4)

The transient hard X-ray tail of GX 17+2: New BeppoSAX results.

FARINELLI R., FRONTERA F., ZDZIARSKI A.A., STELLA L., ZHANG S.N., VAN DER KLIS M., MASETTI N. and AMATI L.

Abstract (from CDS):

We report on results of two BeppoSAX observations of the Z source GX 17+2. In both cases the source is in the horizontal branch of the colour-intensity diagram. The persistent continuum can be fit by two-component models consisting of a blackbody plus a Comptonization spectrum. With one of these models, two solutions for the blackbody temperature of both the observed and seed photons for Comptonization are equally accepted by the data. In the first observation, when the source is on the left part of the horizontal branch, we observe a hard tail extending up to 120keV, while in the second observation, when the source moves towards right in the same branch, the tail is no longer detected. The hard (>30keV) X-ray emission can be modeled either by a simple power-law with photon index Γ∼2.8, or assuming Comptonization of ∼1keV soft photons off a hybrid thermal plus non-thermal electron plasma. The spectral index of the non-thermal injected electrons is p∼1.7. The observation of hard X-ray emission only in the left part of the horizontal branch could be indicative of the presence of a threshold in the accretion rate above which the hard tail disappears. An emission line at 6.7 keV with equivalent width ∼30eV is also found in both observations. We discuss these results and their physical implications.

Abstract Copyright:

Journal keyword(s): stars: individual: GX 17+2 - stars: neutron - X-rays: binaries - accretion, accretion disks

Simbad objects: 10

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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* BR Cir HXB 15 20 40.85 -57 10 00.1   21.4 21.4     ~ 726 1
2 V* V381 Nor HXB 15 50 58.6520652623 -56 28 35.309070422   17.95 16.6     K3III 1040 0
3 V* V818 Sco LXB 16 19 55.0688745859 -15 38 25.019920749 11.60 12.40 11.1     Oev 1533 0
4 V* V1033 Sco HXB 16 54 00.137 -39 50 44.90   15.20 14.2 16.14   F5IV 1726 1
5 V* V821 Ara HXB 17 02 49.3810714542 -48 47 23.163091737 16.20 16.30 15.5     ~ 1791 0
6 V* V1101 Sco LXB 17 05 44.4915929414 -36 25 23.049863107   20.10 18.6     ~ 409 0
7 4U 1758-25 LXB 18 01 09.7308941918 -25 04 44.128444504           ~ 619 1
8 V* NP Ser LXB 18 16 01.389 -14 02 10.62   18.8       K 602 2
9 Granat 1915+105 LXB 19 15 11.54938 +10 56 44.7585           ~ 2320 0
10 V* V1341 Cyg LXB 21 44 41.1544523872 +38 19 17.065856122 15.00 15.13 14.68 15.00   A9III 1080 1

    Equat.    Gal    SGal    Ecl

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2020.11.25-10:37:02

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