The unstable long-term periodicity of Aquila X-1

Kitamoto, Shunji; Tsunemi, H.; Miyamoto, S.; Roussel-Dupré, D.

doi:10.1086/172204

Cited by 37 publications

(38 citation statements)

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“…There is also evidence of periodic components in several other sources. Among the high-mass X-ray binaries, periodicity has been observed in Cyg X-1 at 300 days (Priedhorsky et al 1983 ; also see Kitamoto et al 2000 for the Ginga-ASM observations of a D150 day period), in 4U 1907]09 at 42 days (Priedhorsky & Terrell 1984), and in LMC X-3 at 198 (or 99) days (Cowley et al 1991). Among the low-mass X-ray binaries, Smale & Lochner (1992) found periodicity in three sources, Cyg X-2 (78 days), 4U 1820[303 (175 days), and 4U 1916[053 (199 days).…”

Section: Discussionmentioning

confidence: 93%

“…Some of these sources are of periodic nature, and there has also been discovery of new periodic sources using the RXT E-ASM data (Sco X-1, Peele & White 1996 ; X2127]119, Corbet, Peele, & Smith 1996). Unstable long-term periodicity that is attributed to activity of the companion star or instability of the accretion disk has been observed in Aql X-1 (Kitamoto et al 1993). The ratio of the long and orbital periods in these sources has a wide range, between 5 (in 4U 1907]09) and 22,000 (in 4U 1820[303).…”

Section: Discussionmentioning

confidence: 99%

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Changes in the Long‐Term Intensity Variations in Cygnus X‐2 and LMC X‐3

Paul

Kitamoto

Makino

2000

ApJ

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We report the detection of changes in the long-term intensity variations in two X-ray binaries, Cyg X-2 and LMC X-3. In this work, we have used the long-term light curves obtained with the All-Sky Monitors (ASMs) of the Rossi X-Ray T iming Explorer (RXT E), Ginga, Ariel 5, and V ela 5B and the scanning modulation collimator of HEAO 1. It is found that in the light curves of both the sources, obtained with these instruments at various times over the last 30 years, more than one periodic or quasiperiodic component is always present. The multiple prominent peaks in the periodograms have frequencies unrelated to each other. In Cyg X-2, RXT E-ASM data show strong peaks at 40.4 and 68.8 days, and Ginga-ASM data show strong peaks at 53.7 and 61.3 days. Multiple peaks are also observed in LMC X-3. The various strong peaks in the periodograms of LMC X-3 appear at 104, 169, and 216 days (observed with RXT E-ASM) and 105, 214, and 328 days (observed with Ginga-ASM). The present results, when compared with the earlier observations of periodicities in these two systems, demonstrate the absence of any stable long period. The 78 day periodicity detected earlier in Cyg X-2 was probably due to the short time base in the RXT E data that were used, and the periodicity of 198 days in LMC X-3 was due to a relatively short duration of observation with HEAO 1.

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Changes in the Long‐Term Intensity Variations in Cygnus X‐2 and LMC X‐3

Paul

Kitamoto

Makino

2000

ApJ

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“…Concerning 4U 1630−47, Kuulkers et al (1997) found that the quiescent period between outbursts increased in a linear fashion from ∼600 to ∼700 days between the years 1984 and 1987. As regards Aql X-1, Kitamoto et al (1993) noted that the outburst recurrence time increased substantially over the years, going from 125 days as observed between 1969 and 1979 to 309 days in the period 1987-1992. In both cases, and in particular for Aql X-1, changes in the value ofṀ q from the secondary (possibly induced by chromospheric activity) or instabilities in the accretion disk were invoked to explain the observed behaviour, although none of these modelizations seems to satisfactorily describe these apparent changes in the "internal clock" of these systems (e.g.…”

Section: Discussionmentioning

confidence: 95%

A change in the outburst recurrence time of the Rapid Burster

Masetti¹

2002

A&A

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Abstract. An apparent sudden change in the outburst recurrence time displayed by the Rapid Burster occurred around the end of 1999. The time between consecutive outbursts shrinked from ≈200 to ≈100 days somewhere between November 1999 and March 2000. In parallel, the average peak intensity also decreased of a factor ∼2 in all outbursts occurred after November 1999 with respect to those occurred before this date. I discuss these results by comparing them with similar cases of changes in the recurrence time of other transient X-ray binaries and with the behaviour of Dwarf Novae. A viable explanation is connected with changes in the value of the quiescence mass transfer rate from the secondary, although the detailed origin of these changes remains at best speculative. Further, this result has important implications for programming time-constrained observations of the Rapid Burster both in outburst and in quiescence.

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“…It is located at a distance of D≃5 kpc (e.g., Rutledge et al 2001), and spins at a frequency of νs≃550 Hz (as inferred from coherent X-ray pulsations detected once during a ≃150-s episode; Casella et al 2008). Of all neutron star transient LMXBs known, Aql X-1 has one of the most active accretion histories, displaying outbursts of varying luminosity and duration roughly once every year (e.g., Kaluzienski et al 1977;Kitamoto et al 1993;Güngör et al 2014). Recently, Campana et al (2013) investigated the outburst properties of Aql X-1 over a ≃16-yr period (1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012), revealing 20 outbursts lasting from t ob ≃1 to 26 weeks and with a luminosity ranging from LX≃10 35 to 10 37 (D/5.0 kpc) 2 erg s −1 .…”

Section: Aql X-1mentioning

confidence: 99%

Constraining the properties of neutron star crusts with the transient low-mass X-ray binary Aql X-1

Waterhouse

Degenaar

Wijnands

et al. 2016

Mon. Not. R. Astron. Soc.

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Aql X-1 is a prolific transient neutron star low-mass X-ray binary that exhibits an accretion outburst approximately once every year. Whether the thermal X-rays detected in intervening quiescent episodes are the result of cooling of the neutron star or due to continued low-level accretion remains unclear. In this work we use Swift data obtained after the long and bright 2011 and 2013 outbursts, as well as the short and faint 2015 outburst, to investigate the hypothesis that cooling of the accretion-heated neutron star crust dominates the quiescent thermal emission in Aql X-1. We demonstrate that the X-ray light curves and measured neutron star surface temperatures are consistent with the expectations of the crust cooling paradigm. By using a thermal evolution code, we find that ≃1.2 − 3.2 MeV nucleon −1 of shallow heat release describes the observational data well, depending on the assumed mass-accretion rate and temperature of the stellar core. We find no evidence for varying strengths of this shallow heating after different outbursts, but this could be due to limitations of the data. We argue that monitoring Aql X-1 for up to ≃1 year after future outbursts can be a powerful tool to break model degeneracies and solve open questions about the magnitude, depth and origin of shallow heating in neutron star crusts.

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The unstable long-term periodicity of Aquila X-1

Cited by 37 publications

References 0 publications

Changes in the Long‐Term Intensity Variations in Cygnus X‐2 and LMC X‐3

Changes in the Long‐Term Intensity Variations in Cygnus X‐2 and LMC X‐3

A change in the outburst recurrence time of the Rapid Burster

Constraining the properties of neutron star crusts with the transient low-mass X-ray binary Aql X-1

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