The transient X-ray source A0620-00 - Intensity variations and evidence for an 8 day periodicity

Matilsky, T.; Bradt, H.; Buff, J.; Clark, G. W.; Jernigan, J. G.; Laufer, B.; McClintock, J. E.; Zubrod, D.

doi:10.1086/182320

Cited by 27 publications

(25 citation statements)

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“…Parts of these data have been reported by Doxsey et al (1976), Matilsky et al (1976) and Plaks (1991). We used the data as re-analysed by Plaks (1991), i.e.…”

Section: X-raymentioning

confidence: 62%

“…Moreover, Tsunemi et al (1977) reported an optical period of ∼7.4 days from the three months during the decay. Subsequent reanalysis of the data of Duerbeck & Walter (1976) did not reproduce the ∼3.9 day period (Matilsky et al 1976;Chevalier et al 1980; see also Tsunemi et al 1977). Minima in the optical light curve below the extrapolated general decay (Lloyd et al 1977, Robertson et al 1976) and an eclipse-like feature near the end of the outburst (Chevalier et al 1980) were consistent with the ∼7.4 day variability.…”

Section: Outburstmentioning

confidence: 90%

“…During the first and second exponential decays the source slowly softened as can be seen in Fig. 2b where we plot the hardness ratio using the SAS-3 CSL-A and CSL-B detectors (see also Matilsky et al 1976;Plaks 1991). …”

Section: X-ray Behaviourmentioning

confidence: 99%

“…The subsequent decay was approximately exponential with a decay time scale of ∼29 days up to the beginning of October (Kaluzienski et al 1977;Pounds et al 1977). About one and a half months after X-ray maximum the decay halted for ∼10 days during which the intensity slightly increased (Carpenter et al 1976;Matilsky et al 1976;Kaluzienski et al 1977); this period is called a 'glitch' or secondary maximum in the decay light curve (see e.g. Chen et al 1997).…”

Section: Outburstmentioning

confidence: 99%

“…Tanaka & Lewin 1995;Tanaka & Shibazaki 1996). Before the precursor the spectrum was hard, whereas during the subsequent rise to maximum the spectrum rapidly softened Matilsky et al 1976); the X-ray flux above ∼10 keV actually fell during that period . Near X-ray maximum there was evidence for a hard component above ∼15 keV ; see also White et al 1984), and possibly even above ∼30 keV (Coe, Engel & Quenby 1976).…”

Section: Outburstmentioning

confidence: 99%

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A 0620 - 00 revisited: a black-hole transient case-study

Kuulkers

1998

New Astronomy Reviews

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For the first time we have performed a detailed study of the X-ray, optical and infrared light curves and an intercomparison between these wavelengths (including radio) of the 1975/1976 outburst of the famous black-hole transient A 0620−00 (Nova Mon 1975, V616 Mon). We also investigated the optical behaviour up to a year after the main outburst. This study enabled us to find some new features, which have not been discussed before.During the various stages of the outburst of A 0620−00 we found the X-rays lag the optical on the order of ∼5 to ∼20 days. Moreover, we found evidence that the activity associated with the secondary maximum started even earlier in the infrared. This suggests that most of the processes associated with the outburst occur in the outer parts of the accretion disk.Although various drops in intensity (lasting on the order of a day or more) in the optical and X-ray outburst light curves of A 0620−00 have been reported before, we identified some new ones. One such X-ray 'dip' only appeared in the soft X-rays (1.5-6 keV) whereas at higher energies ( 6 keV) the intensity slightly increases. This shows that the X-ray spectrum pivots near ∼6 keV around that time. In the optical we found evidence for another local maximum around that time (so-called 'intermediate' maximum). The 'intermediate' maximum appears ∼30 days after the secondary maximum, which is close to the viscous time scale of an irradiated accretion disk. We suggest this feature to be an 'echo' of the secondary maximum. At the end of the outburst another local maximum occurs. Since the time difference between the peak of the tertiary maximum and this local maximum is also on the order of the viscous time scale we suggest that this feature is an 'echo' of the tertiary maximum. We find that drops in the optical and X-ray intensity before and during the rise to tertiary maximum are also present in various other short period soft X-ray transients (SXTs). They always occur ∼150 days after the start of the outburst.Although the X-ray spectrum of A 0620−00 gradually softens during the decay from outburst, we find for the first time that it starts to harden again ∼100-150 days after the start of the outburst, similar to that seen in GS 2000+25 and GS 1124−68. This suggests we witness the transition from the so-called high to low state identified in black-hole X-ray binaries. We note that the time of spectral hardening in Preprint submitted to Elsevier Preprint 1 October 2018A 0620−00, GS 2000+25 and GS 1124−68 is simultaneous with the occurrence of the drops in optical and X-ray intensity.We also show that the optical outburst amplitude and the shape of the optical outburst light curve of A 0620−00 closely resembles those of the cataclysmic variable AL Com (where the compact star is a white dwarf). This strengthens the similarity in outburst and quiescent properties of the SXTs and 'Tremendous Outburst Amplitude Dwarf novae' (TOADs) or WZ Sge stars, and shows that in general the optical outburst light curves of both groups are governed...

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“…Parts of these data have been reported by Doxsey et al (1976), Matilsky et al (1976) and Plaks (1991). We used the data as re-analysed by Plaks (1991), i.e.…”

Section: X-raymentioning

confidence: 62%