D. Buckley

X-ray bright sources in the Chandra Small Magellanic Cloud Wing Survey – detection of two new pulsars

ABSTRACT We investigate the X-ray and optical properties of a sample of X-ray bright sourcesfrom the Small Magellanic Cloud (SMC) Wing Survey. We have detected two newpulsars with pulse periods of 65.8 s (CXOU J010712.6-723533) and 700 s (CXOUJ010206.6-714115), and present observations of two previously known pulsars RXJ0057.3-7325 (SXP101) and SAX J0103.2-7209 (SXP348). Our analysis has led tothree new optical identifications for the detected pulsars. We find long-term opticalperiods for two of the pulsars, CXOU J010206.6-714115 and SXP101, of 267 and 21.9d, respectively. Spectral analysis of a sub-set of the sample shows that the pulsarshave harder spectra than the other sources detected. By employing a quantile-basedcolour-colour analysis we are able to separate the detected pulsars from the rest ofthe sample. Using archival catalogues we have been able to identify counterparts forthe majority of the sources in our sample. Combining this with our results from thetemporal analysis of the Chandra data and archival optical data, the X-ray spectralanalysis, and by determining the X-ray to optical flux ratios we present preliminaryclassifications for the sources. In addition to the four detected pulsars, our sampleincludes two candidate foreground stars, 12 probable active galactic nuclei, and fiveunclassified sources.Keywords: X-rays:binaries– stars:emission-line,Be – (galaxies:)MagellanicClouds

INTEGRAL deep observations of the Small Magellanic Cloud

Deep observations of the Small Magellanic Cloud (SMC) and region were carried out in the hard X-ray band by the INTEGRAL observatory in 2008-2009. The field of view of the instrument permitted simultaneous coverage of the entire SMC and the eastern end of the Magellanic Bridge. In total, INTEGRAL detected seven sources in the SMC and five in the Magellanic Bridge; the majority of the sources were previously unknown systems. Several of the new sources were detected undergoing bright X- ray outbursts and all the sources exhibited transient behaviour except the supergiant system SMC X-1. They are all thought to be High Mass X-ray Binary (HMXB) systems in which the compact object is a neutron star.

The Be/X-ray binary LS 992/RX J0812.4-3114: Physical parameters and long-term variability

We present the first long-term optical and infrared study of the optical counterpart to the source RX J0812.4-3114, an X-ray pulsar with a Be type companion. During the period covered by the observations the profile of some Balmer lines changed from absorption to emission and back again to absorption. Contemporaneously, the infrared magnitudes varied by more than 0.8 mag. This long-term variability is interpreted as the formation and subsequent dissipation of the Be stars disc. The building up of the disc ended up in an active X-ray state characterised by regular outbursts occurring at 80 day intervals. The overall duration of the formation/dissipation of the disc is found to be

MASTER OPTICAL POLARIZATION VARIABILITY DETECTION IN THE MICROQUASAR V404 CYG/GS 2023+33

\lesssim 4.3

The 2016 super-Eddington outburst of SMC X-3: X-ray and optical properties and system parameters

years. Optical spectroscopic and infrared photometric observations were used to refine the spectral type of the primary (B0.2IV) and to monitor the circumstellar envelope around the Be star. UBVRI and

Confirmation of six Be X-ray binaries in the Small Magellanic Cloud

uvby\beta

Multiwaveband study of a major X‐ray outburst from the Be/X‐ray transient system A1118–616

photometric observations allowed the determination of the astrophysical parameters of the optical companion.

Optical Counterparts to Be/X-ray Binaries in the Magellanic Clouds

On 2015 June 15 the Swift space observatory discovered that the Galactic black hole candidate V404 Cyg was undergoing another active X-ray phase, after 25 years of inactivity (Barthelmy et al. 2015). Twelve telescopes of the MASTER Global Robotic Net located at six sites across four continents were the first ground based observatories to start optical monitoring of the microquasar after its gamma-ray wakeup at 18h 34m 09s U.T. on 2015 June 15 (Lipunov et al. 2015). In this paper we report, for the first time, the discovery of variable optical linear polarization, changing by 4-6% over a timescale of approximately 1 h, on two different epochs. We can conclude that the additional variable polarization arisies from the relativistic jet generated by the black hole in V404Cyg. The polarization variability correlates with optical brightness changes, increasing when the flux decreases.

The optical counterparts to Be/X-ray binaries in the Magellanic Clouds

On 2016 July 30 (MJD 57599), observations of the Small Magellanic Cloud by Swift/XRT found an increase in X-ray counts coming from a position consistent with the Be/X-ray binary pulsar SMC X-3. Follow-up observations on 2016 August 3 (MJD 57603) and 2016 August 10 (MJD 57610) revealed a rapidly increasing count rate and confirmed the onset of a new X-ray outburst from the system. Further monitoring by Swift began to uncover the enormity of the outburst, which peaked at 1.2 × 1039 erg s−1 on 2016 August 25 (MJD 57625). The system then began a gradual decline in flux that was still continuing over 5 months after the initial detection. We explore the X-ray and optical behaviour of SMC X-3 between 2016 July 30 and 2016 December 18 during this super-Eddington outburst. We apply a binary model to the spin-period evolution that takes into account the complex accretion changes over the outburst, to solve for the orbital parameters. Our results show SMC X-3 to be a system with a moderately low eccentricity amongst the Be/X-ray binary systems and to have a dynamically determined orbital period statistically consistent with the prominent period measured in the OGLE optical light curve. Our optical and X-ray derived ephemerides show that the peak in optical flux occurs roughly 6 d after periastron. The measured increase in I-band flux from the counterpart during the outburst is reflected in the measured equivalent width of the Hα line emission, though the Hα emission itself seems variable on sub-day time-scales, possibly due to the NS interacting with an inhomogeneous disc.

The identification of the optical/IR counterpart to the ROSAT SMC X-ray transient RX J0117.6—7330

This paper is based on ESO data from 079.D−0371 and 088.D−0352. The AAT observations have been supported by the OPTICON project (observing proposals 2011A/014 and 2012/A015), which is funded by the European Commission under the Seventh Framework Programme (FP7). VAM acknowledges financial support from the National Research Foundation of South Africa (Grant 93405) and the World Universities Network. RD, AM and IN from the University of Alicante acknowledge support from the Spanish Government Ministerio de Economia y Competitividad under grant AYA2015-68012-C2-2-P (MINECO/FEDER). ESB acknowledges support from a Claude Leon Foundation fellowship and from the Marie Curie Actions of the European Commission (FP7-COFUND). The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to AU.