A5052978870- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- High-pressure geophysics and materials
- Stellar, planetary, and galactic studies
- Mechanics and Biomechanics Studies
- Geophysics and Gravity Measurements
- Astronomy and Astrophysical Research
- Solar and Space Plasma Dynamics
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Superconducting Materials and Applications
- Cosmology and Gravitation Theories
- Earthquake Detection and Analysis
- Scientific Measurement and Uncertainty Evaluation
- Particle physics theoretical and experimental studies
- Seismic Imaging and Inversion Techniques
- Particle Accelerators and Free-Electron Lasers
- Enzyme Structure and Function
- Galaxies: Formation, Evolution, Phenomena
- X-ray Spectroscopy and Fluorescence Analysis
- Laser-Plasma Interactions and Diagnostics
- Advanced X-ray Imaging Techniques
South African Radio Astronomy Observatory
2016-2024
SKA Telescope, South Africa
2020-2024
University of Cape Town
2015-2020
Parc Científic de la Universitat de València
2017
European Space Astronomy Centre
2017
Foundation for Research and Technology Hellas
2017
Centro de Astrobiología
2017
Universitat de València
2017
University of Turku
2017
Pennsylvania State University
2016
We report on the long-term average spin period, rate of change period and X-ray luminosity during outbursts for 42 Be binary systems in Small Magellanic Cloud. also collect calculate parameters each system use these data to determine that all contain a neutron star which is accreting via disc, rather than wind, if stars are near equilibrium, then over half them, including with periods about 100 s, have magnetic fields quantum critical level 4.4x10^13 G. If not close their inferred be much...
The orbital motion of a neutron star about its optical companion presents window through which to study the parameters that binary system. This has been used extensively in Milky Way calculate these for several high-mass X-ray binaries. Using years RXTE PCA data, we derive four Be/X-ray systems SMC, increasing number with solutions by factor three. We find one new period, confirm second and discuss comparison Galactic systems. Despite low metallicity sit amongst distribution periods...
We present 11 detections of FRB 121102 in ~3 hours observations during its 'active' period on the 10th September 2019. The were made using newly deployed MeerTRAP system and single pulse detection pipeline at MeerKAT radio telescope South Africa. Fortuitously, Nancay this day overlapped with last hour resulted 4 simultaneous detections. MeerKAT's wide band receiver, which extends down to relatively low frequencies (900-1670 MHz usable L-band range), have allowed us get a detailed look...
ABSTRACT Just 10 recurrent novae (RNe) – which erupt repeatedly on time-scales shorter than one century are known in our Galaxy. The most extreme RN (located the Andromeda galaxy), M31N 2008-12a, undergoes a nova eruption every year, and is surrounded by vast ‘super-remnant’, 134 pc extent. Simulations predict that all RNe should be similar shells, but previous searches have failed to detect them. KT Eri has recently been suggested RN, we used Condor Array Telescope image its environs...
Gamma-ray binaries consist of a neutron star or black hole interacting with normal to produce gamma-ray emission that dominates the radiative output system. Only handful such systems have been previously discovered, all within our Galaxy. Here we report discovery Fermi Large Area Telescope (LAT) luminous binary in Magellanic Cloud from search for periodic modulation sources third LAT catalog. This is first system be found outside Milky Way. The has an orbital period 10.3 days and associated...
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 Be/X-ray binary pulsar SMC X-3. Follow-up on August 3 57603) and 10 57610) revealed rapidly increasing count rate confirmed onset new outburst system. Further monitoring Swift began to uncover enormity outburst, which peaked at 1.2 × 1039 erg s−1 25 57625). The system then gradual decline flux that was still continuing over 5 months...
We report the identification from multi-wavelength observations of Fermi Large Area Telescope (LAT) source 4FGL J1405.1-6119 (= 3FGL J1405.4-6119) as a high-mass gamma-ray binary. Observations with LAT show that emission system is modulated at period 13.7135 +/- 0.0019 days, presence two maxima per orbit different spectral properties. X-ray using Neil Gehrels Swift Observatory (XRT) also this period, but single maximum closer to secondary lower-energy maximum. A radio source, coincident...
On MJD 56590-1 (2013 Oct 25-26) observations of the Magellanic Clouds by INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) observatory discovered a previously-unreported bright, flaring X-ray source.This source was initially given identification IGR J00569-7226.Subsequent multi-wavelength identified system as new Be/X-ray binary in Small Cloud.Follow-up Swift and XMM-Newton revealed an pulse period 5.05s that underwent regular occulation/eclipse behaviour every 17d.This is first...
We present evidence for a simple linear relationship between the orbital period and super-orbital in ultra-luminous X-ray (ULX) pulsars, akin to what is seen population of disc-fed neutron star super-giant binary Be/X-ray systems. argue that most likely cause this modulation precessing hot spots or density waves an accretion circumstellar disc by motion system, implying physical link ULX pulsars high-mass (HMXB) pulsars. This hypothesis supported recent studies Galactic Magellanic Cloud...
We report on the discovery of Swift J011511.0-725611, a rare Be X-ray binary system (BeXRB) with White Dwarf (WD) compact object, in Small Magellanic Cloud (SMC) by S-CUBED, weekly X-ray/UV survey SMC Neil Gehrels Observatory. Observations show an approximately 3 month outburst from first detected S-CUBED since it began 2016 June. J011511.0-725611 shows super-soft emission, indicative which is further strengthened presence 0.871 keV edge, commonly attributed to O viii K-edge WD atmosphere....
Phase-targeted RXTE observations have allowed us to detect a transient 71.49 ± 0.02 s signal that is most likely be originating from the supergiant fast X-ray IGR J17544−2619. The phase-folded light curve shows possible double-peaked structure with pulsed flux of ~4.8 × 10-12 erg cm-2 s-1 (3−10 keV). Assuming indicate spin period neutron star in system, provisional location J17544−2619 on Corbet diagram places system within classical wind-fed XRB region. Such result illustrates growing trend...
Abstract We report on the discovery of Swift J010902.6-723710, a rare eclipsing Be/X-ray Binary system by SMC Survey (S-CUBED). J010902.6-723710 was discovered via weekly S-CUBED monitoring observations when it observed to enter state X-ray outburst 2023 October 10. emission found be modulated 182 s period. Optical spectroscopy is used confirm presence highly inclined circumstellar disk surrounding B0-0.5Ve optical companion. Historical UV and IR photometry then identify strong eclipse-like...
The gamma-ray binary system PSR B1259−63/LS 2883 consists of a 48 ms pulsar orbiting Be star. is particularly interesting because it the only where nature compact object known. non-thermal radiation from powered by spin-down luminosity and unpulsed originates stand-off shock front which forms between stellar wind. star/optical companion in produces an excess infrared (IR) flux associated circumstellar disc. This IR provides additional photon source for inverse Compton scattering. We discuss...
Abstract Observations with the Fermi Large Area Telescope (LAT) of gamma-ray source 4FGL J1702.7−5655, previously classified as a candidate millisecond pulsar, show highly significant modulation at period 0.2438033 days (∼5.85 hr). Further examination folded light curve indicates presence narrow eclipses, suggesting that this is redback binary system. An long-term properties over 13 years LAT observations orbital gamma rays changed from simple eclipse before early 2013 to broader, more...
In the course of XMM-Newton survey Small Magellanic Cloud (SMC), two new bright X-ray sources were discovered exhibiting spectral characteris- tics High Mass Binaries - but revealing only weak evidence for pulsations in just one objects(at 153s XMMUJ010743.1-715953). The accurate X- ray source locations permit identification these with Be stars, thereby strongly suggesting systems are Be/X-ray binaries. From blue spectra proposed classification XMMUJ010633.1-731543 is B0.5-1Ve and...
We report the results of a comprehensive analysis X-ray (Chandra and Swift observatories), optical (Southern African Large Telescope, SALT) near-infrared (the VVV survey) observations Be/X-ray binary pulsar 2S1553-542. Accurate coordinates for source are determined used to identify faint optical/infrared counterpart first time. Using SALTICAM photometry, we have constructed spectral energy distribution (SED) this star found moderate NIR excess that is typical Be stars arises due presence...
We combine the decade long photometry of Be/X-ray binary system A0538-66 provided by MACHO and OGLE IV projects with high resolution SALT spectroscopy to provide detailed constraints on orbital parameters properties. The ~420d superorbital modulation is present throughout, but has reduced in amplitude recent years. well-defined 16.6409d outbursts, which were a strong function phase data (not occurring at all maximum), are throughout coverage. However, their reduces during maximum. have...
Deep observations of the Small Magellanic Cloud (SMC) and region were carried out in hard X-ray band by INTEGRAL observatory 2008–2009. The field view instrument permitted simultaneous coverage entire SMC eastern end Bridge. In total, detected seven sources five Bridge; majority previously unknown systems. Several new undergoing bright outbursts all exhibited transient behaviour except supergiant system X-1. They are thought to be high-mass binary systems which compact object is a neutron star.
In the course of XMM-Newton survey Small Magellanic Cloud (SMC), a region to east emission nebula N19 was observed in November 2009. To search for new candidates high mass X-ray binaries EPIC PN and MOS data detected point sources were investigated their spectral temporal characteristics identified. A transient (XMMUJ005011.2-730026= SXP214) with pulse period 214.05 s discovered; source had hard spectrum power-law index ~0.65. The accurate location permits identification ~15th magnitude Be...
On 30th August 2006 SXP18.3 a high mass X-ray binary (HMXB) in the Small Magellanic Cloud (SMC) with an 18.3s pulse period was observed by Rossi Timing Explorer (RXTE). The source seen continuously for following 36 weeks. This is longest Type II outburst ever from HMXB SMC. During located serendipitous XMM-Newton observations. identification of optical counterpart has allowed to be classified as Be/X-ray binary. paper will report on analysis and weekly RXTE data that span last 10 years....
We present X-ray and optical data on the Be/X-ray binary (BeXRB) pulsar IGR J01054-7253 = SXP11.5 in Small Magellanic Cloud (SMC). Rossi Timing Explorer (RXTE) observations of this source a large outburst reveal an 11.483 +/- 0.002s pulse period show both accretion driven spin-up neutron star motion around companion through Doppler shifting spin period. Model fits to these suggest orbital 36.3 0.4d Pdot (4.7 0.3) x 10^{-10} ss^{-1}. solution for system, making it one best described BeXRB...
One of the goals XMM-Newton survey Small Magellanic Cloud is study Be/X-ray binary population. During one our first observations a bright new transient - XMMUJ004814.0-732204 was discovered. We present analysis EPIC X-ray data together with optical observations, to investigate spectral and temporal characteristics XMMUJ004814.0-732204. found coherent pulsations in period (11.86642 +/- 0.00017) s. The spectrum can be modelled by an absorbed power-law indication for soft excess. Depending on...
We present an optical and X-ray study of four Be/X-ray binaries located in the Small Magellanic Cloud (SMC). OGLE I-band data up to 11 years semicontinuous monitoring has been analysed for SMC X-2, SXP172 SXP202B, providing both a measurement orbital period (Porb= 18.62, 68.90 229.9 d pulsars, respectively) detailed profile each pulsar. For this allowed direct comparison emission seen through regular RXTE monitoring, revealing that outbursts precede by around 7 d. Recent studies XMM–Newton...
Gamma-ray binaries are a small subclass of the high mass X-ray binary population that exhibit emission across whole electromagnetic spectrum. We present radial velocities 1FGL J1018.6−5856 based on observations obtained with Southern African Large Telescope. combine our measurements those published in literature to get broad phase coverage. The function supports neutron star compact object, although black hole is possible for very low inclination angles. improved coverage allows constraints...