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Register a new userX-ray and optical periodicities in X-ray binaries. I.A0535+26
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A homogeneous set of UBV photometry (354 data points obtained between 1983 and 1998) for the Be/X-ray binary A0535+26 = V725Tau is analysed, aiming to look for possible periodic component(s). After subtraction of the long-term variation it was found that only a 103-day periodic component remains in the power spectra in both the V and B colour bands. The probability of chance occurrence of such a peak is less than 0.1%. There are no signs of optical variability at the X-ray period (111 d). We discuss possible reasons for a 103-day modulation and suggest that it corresponds to a beat frequency of the orbital period of the neutron star and the precession period (~1400 d) either of an accretion disc around the neutron star or a warped decretion disc around the Be star.
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We present results from an H-alpha monitoring campaign of the Be X-ray binary systems HDE 245770 = A 0535+26 and X Per. We use the H-alpha equivalent widths together with adopted values of the Be star effective temperature, disk inclination, and disk outer boundary to determine the half-maximum emission radius of the disk as a function of time. The observations of HDE 245770 document the rapid spectral variability that apparently accompanied the regeneration of a new circumstellar disk. This disk grew rapidly during the years 1998 - 2000, but then slowed in growth in subsequent years. The outer disk radius is probably truncated by resonances between the disk gas and neutron star orbital periods. Two recent X-ray outbursts appear to coincide with the largest disk half-maximum emission radius attained over the last decade. Our observations of X Per indicate that its circumstellar disk has recently grown to near record proportions, and concurrently the system has dramatically increased in X-ray flux, presumably the result of enhanced mass accretion from the disk. We find that the H-alpha half-maximum emission radius of the disk surrounding X Per reached a size about six times larger than the stellar radius, a value, however, that is well below the minimum separation between the Be star and neutron star. We suggest that spiral arms excited by tidal interaction at periastron may help lift disk gas out to radii where accretion by the neutron star companion becomes more effective.
We present recent contemporaneous X-ray and optical observations of the Be/X-ray binary system A,0535+26 with the textit{Fermi}/Gamma-ray Burst Monitor (GBM) and several ground-based observatories. These new observations are put into the context of the rich historical data (since $sim$1978) and discussed in terms of the neutron star Be-disk interaction. The Be circumstellar disk was exceptionally large just before the 2009 December giant outburst, which may explain the origin of the unusual recent X-ray activity of this source. We found a peculiar evolution of the pulse profile during this giant outburst, with the two main components evolving in opposite ways with energy. A hard 30-70 mHz X-ray QPO was detected with GBM during this 2009 December giant outburst. It becomes stronger with increasing energy and disappears at energies below 25,keV. In the long-term a strong optical/X-ray correlation was found for this system, however in the medium-term the H$_alpha$ EW and the V-band brightness showed an anti-correlation after $sim$2002 Agust. Each giant X-ray outburst occurred during a decline phase of the optical brightness, while the H$_alpha$ showed a strong emission. In late 2010 and before the 2011 February outburst, rapid V/R variations are observed in the strength of the two peaks of the H$_alpha$ line. These had a period of $sim$,25 days and we suggest the presence of a global one-armed oscillation to explain this scenario. A general pattern might be inferred, where the disk becomes weaker and shows V/R variability beginning $sim$,6 months following a giant outburst.
We compiled X-ray and Optical observations of the accreting X-ray binary system A 0535+262 since its discovery in 1975, that will allow us to shed light on the unpredictable behavior of this binary system. We present the data in terms of the Be-disk interaction with the neutron star companion. In addition, we show recent results from the continuous monitoring of this source by the Gamma-ray Burst Monitor(GBM), on board the Fermi observatory, since its launch in 2008 June 11.
Using data from the All Sky Monitor (ASM) on the Rossi X-ray Timing Explorer (RXTE) we have searched for long term periodicities in the X-ray flux of GX 1+4, Sco X-2 (GX 349+2), and GX 339-4. For GX 1+4 we also used data from BATSE and Galactic Centre scans performed by RXTE. We find no evidence for X-ray modulations at the suggested ~304 d orbital period of GX 1+4. However, we find tentative evidence for a periodicity at 420 d to 460 d. An upper limit of 15% peak-to-peak is set on any sinusoidal modulation in the 1.5 - 3.0 keV flux of Sco X-2 for periods in the 30 to 100 d range. For GX 339-4 we confirm the Low State modulation and report the detection of significant low-frequency modulations in both the High State and Very High State. We fail to detect this modulation in the Off State. We show that if the reported orbital period of GX 339-4 lies in the range 0.5 - 1.7 d, then it is not present in the RXTE ASM light curve.
This chapter discusses the implications of X-ray binaries on our knowledge of Type Ibc and Type II supernovae. X-ray binaries contain accreting neutron stars and stellar--mass black holes which are the end points of massive star evolution. Studying these remnants thus provides clues to understanding the evolutionary processes that lead to their formation. We focus here on the distributions of dynamical masses, space velocities and chemical anomalies of their companion stars. These three observational features provide unique information on the physics of core collapse and supernovae explosions within interacting binary systems. There is suggestive evidence for a gap between ~2-5 Msun in the observed mass distribution. This might be related to the physics of the supernova explosions although selections effects and possible systematics may be important. The difference between neutron star mass measurements in low-mass X-ray binaries (LMXBs) and pulsar masses in high-mass X-ray binaries (HMXBs) reflect their different accretion histories, with the latter presenting values close to birth masses. On the other hand, black holes in LMXBs appear to be limited to <~12 Msun because of strong mass-loss during the wind Wolf-Rayet phase. Detailed studies of a limited sample of black-hole X-ray binaries suggest that the more massive black holes have a lower space velocity, which could be explained if they formed through direct collapse. Conversely, the formation of low-mass black holes through a supernova explosion implies that large escape velocities are possible through ensuing natal and/or Blaauw kicks. Finally, chemical abundance studies of the companion stars in seven X-ray binaries indicate they are metal-rich (all except GRO J1655-40) and possess large peculiar abundances of alpha-elements (Abridged)
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