2003A&A...398.1103R


C.D.S. - SIMBAD4 rel 1.7 - 2020.06.04CEST23:06:03

2003A&A...398.1103R - Astronomy and Astrophysics, volume 398, 1103-1110 (2003/2-2)

Aperiodic variability of low-mass X-ray binaries at very low frequencies.

REIG P., PAPADAKIS I. and KYLAFIS N.D.

Abstract (from CDS):

We have obtained discrete Fourier power spectra of a sample of persistent low-mass neutron-star X-ray binaries using long-term light curves from the All Sky Monitor on board the Rossi X-ray Timing Explorer. Our aim is to investigate their aperiodic variability at frequencies in the range 1x10–7-5x10–6Hz and compare their properties with those of the black-hole source Cyg X-1. We find that the classification scheme that divides LMXBs into Z and atoll sources blurs at very low frequencies. Based on the long-term (∼years) pattern of variability and the results of power-law fits (P(ν)∝ν–α) to the 1x10–7-5x10–6Hz power density spectra, low-mass neutron-star binaries fall into three categories. Type I includes all Z sources, except Cyg X-2, and the atoll sources GX9+1 and GX13+1. They show relatively flat power spectra (α≲0.9) and low variability (rms≲20%). Type II systems comprise 4U 1636-53, 4U 1735-44 and GX3+1. They are more variable (20%≲rms≲30%) and display steeper power spectra (0.9≲α≲1.2) than type I sources. Type III systems are the most variable (rms>30%) and exhibit the steepest power spectra (α>1.2). The sources 4U 1705-44, GX354-0 and 4U 1820-30 belong to this group. GX9+9 and Cyg X-2 appear as intermediate systems in between type I and II and type II and III sources, respectively. We speculate that the differences in these systems may be caused by the presence of different types of mass-donor companions. Other factors, like the size of the accretion disc and/or the presence of weak magnetic fields, are also expected to affect their low-frequency X-ray aperiodic varibility.

Abstract Copyright:

Journal keyword(s): stars: neutron - binaries: close - X-rays: binaries - accretion: accretion discs

Status at CDS:  

Simbad objects: 16

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Number of rows : 16

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 V* V818 Sco LXB 16 19 55.0688745859 -15 38 25.019920749 11.60 12.40 11.1     Oev 1525 0
2 V* V801 Ara LXB 16 40 55.5979962948 -53 45 04.953475039 17.50 18.20 17.5   17.07 ~ 785 1
3 4U 1642-45 LXB 16 45 47.7 -45 36 40           ~ 379 1
4 V* V1101 Sco LXB 17 05 44.4915929414 -36 25 23.049863107   20.10 18.6     ~ 406 0
5 4U 1705-44 LXB 17 08 54.470 -44 06 07.35           ~ 354 0
6 V* V2216 Oph LXB 17 31 44.17 -16 57 40.9 16.40 17.10 16.8     ~ 262 1
7 NAME Slow Burster LXB 17 31 57.73 -33 50 02.5           ~ 758 1
8 V* V926 Sco LXB 17 38 58.3 -44 27 00 16.90 17.70 17.5     ~ 426 0
9 X Sgr X-1 LXB 17 47 56.0 -26 33 49           ~ 345 0
10 4U 1758-25 LXB 18 01 09.7308941918 -25 04 44.128444504           ~ 612 1
11 X Sgr X-3 LXB 18 01 32.3 -20 31 44           ~ 219 1
12 V* V5512 Sgr LXB 18 14 31.55 -17 09 26.7           K5III 350 0
13 V* NP Ser LXB 18 16 01.389 -14 02 10.62   18.8       K 597 2
14 X Sgr X-4 LXB 18 23 40.57 -30 21 40.6   19.06 18.81     ~ 900 1
15 HD 226868 HXB 19 58 21.6758193269 +35 12 05.782512305 9.38 9.72 8.91 8.42   O9.7Iabpvar 3906 0
16 V* V1341 Cyg LXB 21 44 41.1544523872 +38 19 17.065856122 15.00 15.13 14.68 15.00   A9III 1066 1

    Equat.    Gal    SGal    Ecl

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2020.06.04-23:06:03

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