Swift observations of SMC X-3 during its 2016 super-Eddington outburst

The Be X-ray pulsar, SMC X-3 underwent a giant outburst in 2016, which was monitored with the Swift satellite. During the outburst, the fluxes in the broadband increased dramatically, and the 0.6--10 keV unabsorbed luminosity reached an extreme value of $\sim 10^{39}$ erg/s around August 24. Using the Swift/XRT data, we measure the observed pulse frequency of neutron star to compute the orbital elements of the binary. After applying the orbital corrections to Swift observations, we find that the spin frequency increases steadily from 128.02 mHz on August 10 and becomes close to the spin equilibrium $\sim 128.73$ mHz at the late time ($L_{\rm X} \sim 2.3\times10^{37}$ erg/s), indicating a strong magnetic field of neutron star $B \sim 7.3\times10^{12}$ G. The spin-up rate is tightly correlated with the X-ray luminosity during the super-Eddington outburst. The pulse profiles exhibited in the Swift/XRT data are variable, showing double peaks at the early stage and then merging into the single peak at the low luminosity. Additionally, we report that a low temperature ($kT \sim 0.1$ keV) thermal component emerges in the phase-averaged spectra as the flux decays, and it could arise from the outer truncated disk or the boundary layer.

Comments: 5 pages, 5 figures, 1 table

Similar Publications

We consider the electromagnetic radiation from newborn binary black holes (BBHs) formed by the evolution of isolated massive stellar binaries. Before the formation of a BBH, the binary consists of a primary black hole (BH) and a secondary Wolf-Rayet star. We investigate two types of transients from the birth of a secondary BH: one powered by the Bondi-Hoyle-Lyttleton accretion onto the primary BH, and the other induced by accretion onto the secondary BH. Read More


An energy extracting black hole magnetosphere can be defined by the location of its inner Alfv\'{e}n surface, which determines the rate of black hole energy extraction along a given magnetic field line. We study how the location of the inner Alfv\'{e}n surface can modify the structure of energy extracting black hole magnetospheres in the force-free limit. Hundreds of magnetospheres are numerically computed via a general relativistic extension of the Newtonian magnetofrictional method for a full range of black hole spins and flow parameters. Read More


The equilibrium-diffusion approximation (EDA) is used to describe certain radiation-hydrodynamic (RH) environments. When this is done the RH equations reduce to a simplified set of equations. The EDA can be derived by asymptotically analyzing the full set of RH equations in the equilibrium-diffusion limit. Read More


Here we present the evidence for periodicity of an optical emission detected in several AGN. Significant periodicity is found in light curves and radial velocity curves. We discuss possible mechanisms that could produce such periodic variability and their implications. Read More


2017Feb
Affiliations: 1Univ. Paris-Sud, Orsay, 2ICRR, University of Tokyo, 3Universite Libre de Bruxelles

Ultra-high energy cosmic rays (UHECRs) are particles, likely protons and/or nuclei, with energies up to $10^{20}$ eV that are observed through the giant air showers they produce in the atmosphere. These particles carry the information on the most extreme phenomena in the Universe. At these energies, even charged particles could be magnetically rigid enough to keep track of, or even point directly to, the original positions of their sources on the sky. Read More


We propose to use degree-scale angular clustering of fast radio bursts (FRBs) to identify their origin and the host galaxy population. We study the information content in auto-correlation of the angular positions and dispersion measures (DM) and in cross-correlation with galaxies. We show that the cross-correlation with Sloan Digital Sky Survey (SDSS) galaxies will place stringent constraints on the mean physical quantities associated with FRBs. Read More


The third Fermi Large Area Telescope (LAT) $\gamma$-ray source catalog (3FGL) contains over 1000 objects for which there is no known counterpart at other wavelengths. The physical origin of the $\gamma$-ray emission of those objects is unknown. Such objects are commonly referred to as unassociated and mostly do not exhibit significant $\gamma$-ray flux variability. Read More


The discovery of gravitational waves by the international collaboration LIGO (Laser Interferometer Gravitational-Wave Observatory)/Virgo on the one hand is a triumphant confirmation of the general theory of relativity, and on the other confirms the general fundamental ideas on the nuclear evolution of baryon matter in the Universe concentrated in binary stars. LIGO/Virgo may turn out to be the first experiment in the history of physics to detect two physical entities, gravitational waves and black holes Read More


Ten weeks' daily imaging of the giant elliptical galaxy M87 with the Hubble Space Telescope has yielded 41 nova light curves of unprecedented quality for extragalactic cataclysmic variables. We have recently used these light curves to demonstrate that the observational scatter in the so-called Maximum-Magnitude Rate of Decline (MMRD) relation for classical novae is so large as to render the nova-MMRD useless as a standard candle. Here we demonstrate that the Buscombe - de Vaucouleurs hypothesis, that all novae converge to nearly the same absolute magnitude about two weeks after maximum light, is strongly supported by our M87 nova data. Read More


Ultra-high-energy cosmic rays (UHECRs) can be accelerated by tidal disruption events of stars by black holes. Encounters between white dwarfs with intermediate-mass black holes (IMBHs) provide a natural environment for acceleration, as tidal forces can ignite nuclear burn and lead to a supernova explosion. The numbers of IMBHs may be substantially augmented once account is taken of their likely presence in dwarf galaxies. Read More