The understanding of the accretion process on to compact objects in binary systems is an important part of modern astrophysics. Theoretical work, primarily that of Ghosh & Lamb (1979), has made clear predictions for the behaviour of such systems which have been generally supported by observational results of considerably varying quality from galactic accreting pulsar systems. In this work a much larger homogeneous population of such objects in the Small Magellanic Cloud (SMC) is used to provide more demanding tests of the accretion theory. The results are extremely supportive of the theoretical models and provide useful statistical insights into the manner in which accreting pulsars behave and evolve.
Be X-ray binaries (BeXRBs) consist of rapidly rotating Be stars with neutron star companions accreting from the circumstellar emission disk. We compare the observed population of BeXRBs in the Small Magellanic Cloud with simulated populations of BeXRB-like systems produced with the COMPAS population synthesis code. We focus on the apparently higher minimal mass of Be stars in BeXRBs than in the Be population at large. Assuming that BeXRBs experienced only dynamically stable mass transfer, their mass distribution suggests that at least 30% of the mass donated by the progenitor of the neutron st…
StrayCats, the catalog of NuSTAR stray light observations, contains data from bright X-ray sources that fall within crowded source regions. These observations offer unique additional data with which to monitor sources like X-ray binaries that show variable timing behavior. In this work, we present a timing analysis of stray light data of the high mass X-ray binary SMC X-1, the first scientific analysis of a single source from the StrayCats project. We describe the process of screening stray light data for scientific analysis, verify the orbital ephemeris, and create both time and energy resolv…
Exploring LSST's capabilities for early detection of outbursts in low-mass X-ray binaries
International Centre for Radio Astronomy Research, Curtin University（国际射电天文中心，科廷大学）；New York University Abu Dhabi（阿布扎比纽约大学）；University of Michigan-Dearborn（密歇根大学迪尔伯恩分校）
We present the two-point cross-correlation function between high-mass X-ray binaries (HMXBs) in the Small Magellanic Cloud (SMC) and their likely birthplaces (OB Associations: OBAs). This function compares the spatial correlation between the observed HMXB and OBA populations against mock catalogs in which the members are distributed randomly across the sky. A significant correlation (15 sigma) is found for the HMXB and OBA populations when compared with a randomized catalog in which the OBAs are distributed uniformly over the SMC. A less significant correlation (4 sigma) is found for a randomi…
The Einstein Telescope (ET), a wide-band, future third generation gravitational wave detector, is expected to have detection rates of $\sim 10^5 - 10^6$ binary black hole (BBH) detections and $\sim 7 \times 10^4$ binary neutron star (BNS) detections in one year. The coalescence of compact binaries with a total mass of 20 - 100 $M_{\odot}$, typical of BH-BH or BH-NS binaries, will be visible up to redshift $z\approx 20$ and even higher, thus facilitating the understanding of the dark era of the Universe preceding the birth of the first stars. The ET will therefore be a crucial instrument for po…
Populations of evolved massive binary stars in the Small Magellanic Cloud I: Predictions from detailed evolution models
Universität Bonn（波恩大学）；Argelander-Institut für Astronomie, Universität Bonn（波恩大学阿尔兰德天体物理研究所）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）；Max-Planck-Institut für Extraterrestrische Physik（马克斯·普朗克地外物理学研究所）；Tel Aviv University（特拉维夫大学）
Context. The Small Magellanic Cloud (SMC) hosts many known high-mass X-ray binaries (HMXBs), and all but one (SMC X-1) have a Be companion star. Through the calibration and verification phase of eROSITA on board the Spektrum-Roentgen-Gamma (SRG) spacecraft, the Be/X-ray binary XMMU J010429.4-723136 was in the field of view during observations of the supernova remnant, 1E0102.2-7219, used as a calibration standard. Aims. We report timing and spectral analyses of XMMU J010429.4-723136 based on three eROSITA observations of the field, two of which were performed on 2019 November 7-9, with the thi…
Compact binaries such as double neutron stars or a neutron star paired with a black-hole, are strong sources of gravitational waves during coalescence and also the likely progenitors of various electromagnetic phenomena, notably short-duration gamma-ray bursts (SGRBs), and kilonovae. In this work, we generate populations of synthetic binaries and place them in galaxies from the large-scale hydrodynamical galaxy evolution simulation EAGLE. With our zELDA code, binaries are seeded in proportion to star formation rate, and we follow their evolution to merger using both the BPASS and COSMIC binary…
Hundreds of millions of supermassive black hole binaries are expected to contribute to the gravitational-wave signal in the nanohertz frequency band. Their signal is often approximated either as an isotropic Gaussian stochastic background with a power-law spectrum, or as an individual source corresponding to the brightest binary. In reality, the signal is best described as a combination of a stochastic background and a few of the brightest binaries modeled individually. We present a method that uses this approach to efficiently create realistic pulsar timing array datasets using synthetic cata…
Population synthesis of Be X-ray binaries in the Small Magellanic Cloud: Angular momentum recycling and stable mass transfer
Universität Heidelberg（海德堡大学）；University of Cambridge（剑桥大学）；University of Padova（帕多瓦大学）；Gran Sasso Science Institute (GSSI)（格兰萨索科学研究所）；INFN, Sezione di Padova（意大利国家核物理研究所帕多瓦分部）；University of Amsterdam（阿姆斯特丹大学）；Universitat de Barcelona (UB)（巴塞罗那大学）
