C.D.S. - SIMBAD4 rel 1.7 - 2021.04.13CEST00:45:39

2012A&A...546A..35C - Astronomy and Astrophysics, volume 546A, 35-35 (2012/10-1)

Spectral investigations of the nature of the Scorpius X-1 like sources.


Abstract (from CDS):

We present results of spectral investigations of the Sco X-1 like Z-track sources Sco X-1, GX 349+2, and GX 17+2 based on Rossi-XTE (RXTE) observations determining spectral evolution along the Z-track.
Result. are obtained for a spectral model describing an extended accretion disk corona. The results are compared with previous results for the Cyg X-2 like group: Cyg X-2, GX 340+0, and GX 5-1 and a general model for the Z-track sources proposed. On the normal branch, the Sco-like and Cyg-like sources are similar, the results indicating an increase of mass accretion rate {dot}(M) between soft and hard apex, not as in the standard view that this increases monotonically around the Z. In the Cyg-like sources, increasing {dot}(M) causes the neutron star temperature kT to increase from ∼1 to ∼2keV. At the lower temperature, the radiation pressure is small, but at the higher kT, the emitted flux of the neutron star is several times super-Eddington and the high radiation pressure disrupts the inner disk and launches the relativistic jets observed on the upper normal and horizontal branches. In the Sco-like sources, the main physical difference is the high kT of more than 2keV on all parts of the Z-track suggesting jets are always possible, even on the flaring branch. The flaring branch in the Cyg-like sources is associated with a release of energy on the neutron star consistent with unstable nuclear burning. The Sco-like sources are very different as flaring appears to be a combination of unstable burning and an increase of {dot}(M) which makes flaring much stronger. Analysis of 15 years of RXTE ASM data on all 6 classic Z-track sources shows the high rate and strength of flaring in the Sco-like sources suggesting that the continual release of energy heats the neutron star causing the high kT. Analysis of a Sco X-1 observation with unusually little flaring supports this. GX 17+2 appears to be transitional between the Cyg and Sco-like types. Our results do not support the suggestion that Cyg or Sco-like nature is determined by the luminosity.

Abstract Copyright:

Journal keyword(s): accretion, accretion disks - acceleration of particles - binaries: close - stars: neutron - X-rays: binaries - X-rays: general

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
1 V* V818 Sco LXB 16 19 55.0688745859 -15 38 25.019920749 11.60 12.40 11.1     Oev 1543 0
2 4U 1642-45 LXB 16 45 47.7 -45 36 40     14.30     ~ 388 1
3 [KRL2007b] 214 LXB 17 00 58.46 -46 11 08.6           ~ 210 0
4 V* V1101 Sco LXB 17 05 44.4915929414 -36 25 23.049863107   20.10 18.6     ~ 413 0
5 4U 1758-25 LXB 18 01 09.7308941918 -25 04 44.128444504     11.08     ~ 624 1
6 V* NP Ser LXB 18 16 01.389 -14 02 10.62   18.8       K 608 2
7 V* V1341 Cyg LXB 21 44 41.1544523872 +38 19 17.065856122 15.00 15.13 14.68 15.00   A9III 1093 1

    Equat.    Gal    SGal    Ecl

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