GX 5−1 and GX 17+2 with EXOSAT: New insights in two Z-sources

Kuulkers, E.; Klis, M. van der; Oosterbroek, T.; Paradijs, J.A. van; Lewin, W. H. G.

doi:10.1063/1.45934

Cited by 64 publications

(131 citation statements)

References 0 publications

Supporting

Mentioning

119

Contrasting

Order By: Relevance

“…To obtain the exact count rate in each of these energy bands we interpolated linearly in channel space. To correct for the gain changes and differences in the effective area between the PCUs, as well as to correct for the differences due to changes in the channel-to-energy conversion of the PCUs as a function of time, we normalised by the Crab Nebula values obtained close in time to our observations (for details see Kuulkers et al 1994;Altamirano et al 2008). We finally averaged the normalised colours and intensity per PCU for the full observation using all available PCUs.…”

Section: Intensity and Colours Of 4u 1636-53mentioning

confidence: 99%

“…In order to study the evolution of the individual spectral components in relation to the position of the source in the CD, we ordered the observations according to their colour-colour coordinate Sz, which is thought to be a function of the mass accretion rate (see e.g., Kuulkers et al 1994). The order of the six XMM-Newton/RXTE observations according with their Sz value is: 1-6-2-3-5-4.…”

Section: Continuum Parametersmentioning

confidence: 99%

See 1 more Smart Citation

Broad iron line in the fast spinning neutron-star system 4U 1636−53

Sanna

Hiemstra

Méndez

et al. 2013

Monthly Notices of the Royal Astronomical Society

111

View full text Add to dashboard Cite

We analysed the X-ray spectra of six observations, simultaneously taken with XMMNewton and Rossi X-ray Timing Explorer (RXTE), of the neutron star low-mass X-ray binary 4U 1636-53. The observations cover several states of the source, and therefore a large range of inferred mass accretion rate. These six observations show a broad emission line in the spectrum at around 6.5 keV, likely due to iron. We fitted this line with a set of phenomenological models of a relativistically broadened line, plus a model that accounts for relativistically smeared and ionised reflection from the accretion disc. The latter model includes the incident emission from both the neutronstar surface or boundary layer and the corona that is responsible for the high-energy emission in these systems. From the fits with the reflection model we found that in four out of the six observations the main contribution to the reflected spectrum comes from the neutron-star surface or boundary layer, whereas in the other two observations the main contribution to the reflected spectrum comes from the corona. We found that the relative contribution of these two components is not correlated to the state of the source. From the phenomenological models we found that the iron line profile is better described by a symmetric, albeit broad, profile. The width of the line cannot be explained only by Compton broadening, and we therefore explored the case of relativistic broadening. We further found that the direct emission from the disc, boundary layer, and corona generally evolved in a manner consistent with the standard accretion disc model, with the disc and boundary layer becoming hotter and the disc moving inwards as the source changed from the hard in to the soft state. The iron line, however, did not appear to follow the same trend.

show abstract

Section: Intensity and Colours Of 4u 1636-53mentioning

confidence: 99%

Section: Continuum Parametersmentioning

confidence: 99%

Broad iron line in the fast spinning neutron-star system 4U 1636−53

Sanna

Hiemstra

Méndez

et al. 2013

Monthly Notices of the Royal Astronomical Society

111

View full text Add to dashboard Cite

show abstract

“…We used the following energy bands: 2.0−3.5 keV (A), 3.5−6.0 keV (B), 6.0−9.7 keV (C), and 9.7−16.0 keV (D). We define the soft and hard colours (SC, HC) as the ratios of the count rates in the various bands: SC = B/A and HC = D/C; the intensity (Int) is defined as the sum of the count rates in the four energy bands: Int = A + B + C + D. We normalized both the colours and intensity to the Crab values nearest in time to account for changes in detector gas gain (see, e.g., Kuulkers et al 1994;van Straaten et al 2003). Since the values do not change significantly within an observation (i.e., on time scales of order an hour), they were averaged over one observation.…”

Section: Rxte Pca and Hextementioning

confidence: 99%

What ignites on the neutron star of 4U 0614+091?

Kuulkers¹,

Zand

Atteia

et al. 2010

A&A

Self Cite

103

View full text Add to dashboard Cite

The low-mass X-ray binary 4U 0614+091 is a source of sporadic thermonuclear (type I) X-ray bursts. We find bursts with a wide variety of characteristics in serendipitous wide-field X-ray observations by the WATCH on EURECA, the ASM on RXTE, the WFCs on BeppoSAX, the FREGATE on HETE-2, the IBIS/ISGRI on INTEGRAL, and the BAT on Swift, as well as pointed observations with the PCA and HEXTE on RXTE. Most of the bursts are bright, i.e., they reach a peak flux of about 15 Crab, but a few are weak and only reach a peak flux below a Crab. One of the bursts shows a very strong photospheric radius-expansion phase. This allows us to evaluate the distance to the source, which we estimate to be 3.2 kpc. The burst durations vary generally from about 10 s to 5 min. However, after one of the intermediate-duration bursts, a faint tail is seen to at least about 2.4 h after the start of the burst. One very long burst was observed, which lasted for several hours. This superburst candidate was followed by a normal type-I burst only 19 days later. This is, to our knowledge, the shortest burst-quench time among the superbursters. The observation of a superburst in this system is difficult to reconcile if the system is accreting at about 1% of the Eddington limit. We describe the burst properties in relation to the persistent emission. No strong correlations are apparent, except that the intermediate-duration bursts occurred when 4U 0614+091's persistent emission was lowest and calm, and when bursts were infrequent (on average roughly one every month to 3 months). The average burst rate increased significantly after this period. The maximum average burst recurrence rate is about once every week to 2 weeks. The burst behaviour may be partly understood if there is at least an appreciable amount of helium present in the accreted material from the donor star. If the system is an ultra-compact X-ray binary with a CO white-dwarf donor, as has been suggested, this is unexpected. If the bursts are powered by helium, we find that the energy production per accumulated mass is about 2.5 times less than expected for pure helium matter.

show abstract

“…For some Z sources it is known that the position of the track they trace out in the CD drifts on a time scale of weeks, with shifts in the colours of up to ∼10% (Kuulkers et al 1994;; this effect is called secular motion. It is also seen in the atoll source 4U 1636-53 (Prins & van der Klis 1997;Di Salvo et al 2003), but in the CD it is not as strong as in some Z-sources.…”

Section: Introductionmentioning

confidence: 99%

“…The mass accretion rate (Ṁ) is thought to increase along the HB via the NB to the FB on time scales of hours to days (Hasinger & van der Klis 1989), although on longer time scales the relation withṀ may be more complicated (e.g. Kuulkers et al 1994;Homan et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Peculiar spectral and power spectral behaviour of the LMXB GX 13+1

Schnerr

Reerink

Klis

et al. 2003

A&A

Self Cite

View full text Add to dashboard Cite

Abstract. We present results of an analysis of all 480 ks of Rossi X-ray Timing Explorer Proportional Counter Array data obtained from 17 May 1998 to 11 October 1998 on the luminous low mass X-ray binary GX 13+1. We analysed the spectral properties in colour-colour diagrams (CDs) and hardness-intensity diagrams (HIDs) and fitted the power spectra with a multiLorentzian model. GX 13+1 traces out a curved track in the CDs on a time scale of hours, which is very reminiscent of a standard atoll track containing an island, and lower and upper banana branch. However, both count rate and power spectral properties vary along this track in a very unusual way, not seen in any other atoll or Z source. The count rate, which varied by a factor of ∼1.6, along a given track first decreases and then increases, causing the motion through the HIDs to be in the opposite sense to that in the CD, contrary to all other Z and atoll sources. Along a CD track, the very low frequency noise uniquely decreases in amplitude from ∼5 to ∼2% (rms). The high frequency noise amplitude decreases from ∼4% to less than 1% and its characteristic frequency decreases from ∼10 to ∼5 Hz. The 57-69 Hz quasi-periodic oscillation (QPO) found earlier is also detected, and no kHz QPOs are found. In addition the entire track shows secular motion on a time scale of about a week. The average count rate as well as the amplitude of the very low frequency noise correlate with this secular motion. We discuss a possible explanation for the peculiar properties of GX 13+1 in terms of an unusual orientation or strength of a relativistic jet.

show abstract

GX 5−1 and GX 17+2 with EXOSAT: New insights in two Z-sources

Cited by 64 publications

References 0 publications

Broad iron line in the fast spinning neutron-star system 4U 1636−53

Broad iron line in the fast spinning neutron-star system 4U 1636−53

What ignites on the neutron star of 4U 0614+091?

Peculiar spectral and power spectral behaviour of the LMXB GX 13+1

Contact Info

Product

Resources

About