Discovery of periodic dips in the light curve of GX 13+1: the X-ray orbital ephemeris of the source

Iaria, R.; Salvo, T. Di; Burderi, L.; Riggio, A.; D’Aí, A.; Robba, N. R.

doi:10.1051/0004-6361/201322328

Cited by 18 publications

(28 citation statements)

References 18 publications

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“…This behavior may be connected to the fact that GX 13+1 is probably viewed at a high inclination angle (perhaps 60 • -80 • ) as indicated by observations of absorption dips in this system on several occasions (Díaz Trigo et al 2012;D'Aì et al 2014;Iaria et al 2014). It was recently shown for black hole X-ray transients that the shape of their HID tracks depends on the inclination angle (Muñoz-Darias et al 2013).…”

Section: The Z Source Classification Of Gx 13+1mentioning

confidence: 85%

Common Patterns in the Evolution Between the Luminous Neutron Star Low-Mass X-Ray Binary Subclasses

Fridriksson

Homan

Remillard

2015

ApJ

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The X-ray transient XTE J1701-462 was the first source observed to evolve through all known subclasses of low-magnetic-field neutron star low-mass X-ray binaries (NS-LMXBs), as a result of large changes in its mass accretion rate. To investigate to what extent similar evolution is seen in other NS-LMXBs we have performed a detailed study of the color-color and hardness-intensity diagrams (CDs and HIDs) of Cyg X-2, Cir X-1, and GX 13+1-three luminous X-ray binaries, containing weakly magnetized neutron stars, known to exhibit strong secular changes in their CD/HID tracks. Using the full set of Rossi X-ray Timing Explorer Proportional Counter Array data collected for the sources over the 16 year duration of the mission, we show that Cyg X-2 and Cir X-1 display CD/HID evolution with close similarities to XTE J1701-462. Although GX 13+1 shows behavior that is in some ways unique, it also exhibits similarities to XTE J1701-462, and we conclude that its overall CD/HID properties strongly indicate that it should be classified as a Z source, rather than as an atoll source. We conjecture that the secular evolution of Cyg X-2, Cir X-1, and GX 13+1-illustrated by sequences of CD/HID tracks we construct-arises from changes in the mass accretion rate. Our results strengthen previous suggestions that within single sources Cyg-like Z source behavior takes place at higher luminosities and mass accretion rates than Sco-like Z behavior, and lend support to the notion that the mass accretion rate is the primary physical parameter distinguishing the various NS-LMXB subclasses.

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Section: The Z Source Classification Of Gx 13+1mentioning

confidence: 85%

Common Patterns in the Evolution Between the Luminous Neutron Star Low-Mass X-Ray Binary Subclasses

Fridriksson

Homan

Remillard

2015

ApJ

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“…A comprehensive study on the dipping activity of the source during a time span of more than 14 years was presented in Iaria et al (2014), where evidence was given for a long-term modulation of dip passages at an inferred period of 24.5274(2) d. The phase of the Chandra dip corresponds to the zero-phase of the periodic modulation, and therefore this is the first spectroscopic study of the periodic dip in GX 13+1. The lack of past dip evidence in GX 13+1 may be attributed to the very long orbital period of the source, which exceeds the rest of the dipping class by almost two orders of magnitude, and the possible low duty-cycle of the dips.…”

Section: Nature Of the Dip In The Light Curvementioning

confidence: 95%

“…Iaria et al (2014) systematically searched in archived X-ray observations for clear signatures of periodic dips. Applying timing techniques to long-term folded X-ray light curves provided a successful method that led to a refined orbitalperiod estimate (24.5274(2) d) and to the first ephemeris for the dip passage times.…”

Section: The Source Gx13+1mentioning

confidence: 99%

ChandraX-ray spectroscopy of a clear dip in GX 13+1

D’Aí

Iaria

Salvo

et al. 2014

A&A

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Context. The source GX 13+1 is a persistent, bright Galactic X-ray binary hosting an accreting neutron star. It shows highly ionized absorption features, with a blueshift of ∼400 km s −1 and an outflow-mass rate similar to the accretion rate. Many other X-ray sources exhibit warm absorption features, and they all show periodic dipping behavior at the same time. Recently, a dipping periodicity has also been determined for GX 13+1 using long-term X-ray folded light-curves, leading to a clear identification of one of such periodic dips in an archival Chandra observation. Aims. We give the first spectral characterization of the periodic dip of GX 13+1 found in this archival Chandra observation performed in 2010. Methods. We used Chandra/HETGS data (1.0-10 keV band) and contemporaneous RXTE/PCA data (3.5-25 keV) to analyze the broad-band X-ray spectrum. We adopted different spectral models to describe the continuum emission and used the XSTAR-derived warm absorber component to constrain the highly ionized absorption features. Results. The 1.0−25 keV continuum emission is consistent with a model of soft accretion-disk emission and an optically thick, harder Comptonized component. The dip event, lasting ∼450 s, is spectrally resolved with an increase in the column density of the neutral absorber, while we do not find significant variations in the column density and ionization parameter of the warm absorber with respect to the out-of-dip spectrum. Conclusions. We argue that the very low dipping duty-cycle with respect to other sources of the same class can be ascribed to its long orbital period and the mostly neutral bulge that is relatively small compared with the dimensions of the outer disk radius.

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“…Liu et al 2007). The most recent discovery of dipping behaviour is in the 24.27-d binary and burst source, GX 13+1 (Iaria et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Intermittent dipping in a low-mass X-ray binary

Ajamyan

Upjohn

Stuart

2016

Mon. Not. R. Astron. Soc.

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Periodic dips observed in ≈ 20% of low-mass X-ray binaries are thought to arise from obscuration of the neutron star by the outer edge of the accretion disk. We report the detection with the Rossi X-ray Timing Explorer of two dipping episodes in Aql X-1, not previously a known dipper. The X-ray spectrum during the dips exhibited an elevated neutral column density, by a factor between 1 and almost two orders of magnitude. Dips were not observed in every cycle of the 18.95-hr orbit, so that the estimated frequency for these events is 0.10 +0.07 −0.05 cycle −1 . This is the first confirmed example of intermittent dipping in such a system. Assuming that the dips in Aql X-1 occur because the system inclination is intermediate between the non-dipping and dipping sources, implies a range of 72-79 • for the source. This result lends support for the presence of a massive (> 2 M ⊙ ) neutron star in Aql X-1, and further implies that ≈ 30 additional LMXBs may have inclinations within this range, raising the possibility of intermittent dips in those systems also. Thus, we searched for dips from 24 other bursting systems, without success. For the system with the largest number of dip phases covered, 4U 1820−303, the nondetection implies a 95% upper limit to the dip frequency of 1.4 × 10 −3 cycle −1 .

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Discovery of periodic dips in the light curve of GX 13+1: the X-ray orbital ephemeris of the source

Cited by 18 publications

References 18 publications

Common Patterns in the Evolution Between the Luminous Neutron Star Low-Mass X-Ray Binary Subclasses

Common Patterns in the Evolution Between the Luminous Neutron Star Low-Mass X-Ray Binary Subclasses

ChandraX-ray spectroscopy of a clear dip in GX 13+1

Intermittent dipping in a low-mass X-ray binary

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