Catalog of the Galactic population of X-ray pulsars in High-mass X-ray binary systems

A catalog of the Galactic population of X-ray pulsars in high-mass X-ray binary (HMXB) systems is presented. It contains information about 82 confirmed sources: 18 persistent and 64 transient pulsars. Their basic parameters include spin period, spin evolution with global and local spin-up/spin-down and duration, orbital period, X-ray luminosity, magnetic field strength measured by cyclotron line analysis, distance, spectral and luminosity class, observable parameters of massive companions, which are shown in the tables provided, with corresponding references. Candidates of the HMXB pulsars are also listed for further careful consideration.Comment: 35 pages, 5 figures, 3 tables. Accepted for publication in ApJ

Estimates of the Surface Magnetic Field Strength of Radio Pulsars

We investigate the geometry of the magnetic field of rotation-powered pulsars. A new method for calculating an angle ($\beta$) between the spin and magnetic dipole axes of a neutron star (NS) in the ejector stage is considered within the frame of the magnetic dipole energy loss mechanism. We estimate the surface magnetic field strength ($B_{\rm ns}$) for a population of known neutron stars in the radio pulsar (ejector) stage. The evaluated $B_{\rm ns}(\beta)$ may differ by an order of magnitude from the values without considering the angle $\beta$. It is shown that $B_{\rm ns}(\beta)$ lies in the range $10^{8}$--$10^{14}\,\text{G}$ for a known population of short and middle periodic radio pulsars.Comment: 12 pages, 6 figures, 5 tables, 29 references. Published in Universe in the Special Issue Remo Ruffini Festschrif

What can we learn from GRBs?

We review our recent results on the classification of long and short gamma-ray bursts (GRBs) in different subclasses. We provide observational evidences for the binary nature of GRB progenitors. For long bursts the induced gravitational collapse (IGC) paradigm proposes as progenitor a tight binary system composed of a carbon-oxygen core (COcore) and a neutron star (NS) companion; the supernova (SN) explosion of the COcore triggers a hypercritical accretion process onto the companion NS. For short bursts a NS–NS merger is traditionally adopted as the progenitor. We also indicate additional sub-classes originating from different progenitors: (COcore)–black hole (BH), BH–NS, and white dwarf–NS binaries. We also show how the outcomes of the further evolution of some of these sub-classes may become the progenitor systems of other sub-classes

Gamma-ray bursts within fireshell model

This thesis is mainly focused on careful data analysis of different parts of high-energy (sub-keV--GeV) spectra of gamma-ray bursts. All the interpretation works are based on the theoretical ground of the fireshell paradigm which is being continuously developed for over 20 years. The chapters in the main body of the thesis focus on current research and results obtained and published. A distinct emphasis on spectral bands is expressed through structural division of the thesis: soft gamma-ray emission, x-ray afterglow emission and high-energy gamma-ray emission. In Chapter 2 we discuss theoretical and observational evidences which have been recently gained for a two-fold classification of short bursts within the fireshell working paradigm. We present three additional S-GRBs, 081024B, 090510 and 140402A, following the already identified S-GRBs, i.e., 090227B and 140619B. In Chapter 3 we analyze the early X-ray flares in the GRB "flare-plateau-afterglow" (FPA) phase observed by Swift-XRT. We claim that the FPA occurs only in one of the subclasses---binary-driven hypernovae (BdHNe). This subclass consists of long GRBs with a carbon-oxygen core (CO_core) massive star and a neutron star (NS) binary companion as progenitors. In Chapter 4 we examine a scenario when in binary system of neutron star (NS) and massive CO_core star, the latter undergoes a supernova (SN) explosion. A black hole (BH) subsequently originates from the gravitational collapse of the NS caused by hypercritical accretion of the SN ejecta. We infer a new asymmetric morphology for the BdHNe system where the GeV emission occurs within a cone of half-opening angle approximately 60 degrees normal to the orbital plane of the binary progenitor. We confirm that GeV luminosity light curves follow the universal power-law with index of -1.19 +/- 0.04, and from this we further estimate the spin-down rate of the BH

Catalog of the Galactic Population of X-Ray Pulsars in High-mass X-Ray Binary Systems

A catalog of the Galactic population of X-ray pulsars in high-mass X-ray binary (HMXB) systems is presented. It contains information about 82 confirmed sources: 18 persistent and 64 transient pulsars. Their basic parameters include spin period, spin evolution with global and local spin-up/spin-down and duration, orbital period, X-ray luminosity, magnetic field strength measured by cyclotron line analysis, distance, spectral and luminosity class, and observable parameters of massive companions, which are shown in the tables provided, with corresponding references. Candidates of HMXB pulsars are also listed for further careful consideration

GRB 110731A within the IGC paradigm

Bright gamma-ray burst (GRB) 110731A was simultaneously observed by Fermi and Swift observatories, with a follow up optical observation which inferred the redshift of z = 2.83. Thus, available data are spanning from optical to high energy (GeV) emission. We analyze these data within the induced gravitational collapse (IGC) paradigm, recently introduced to explain temporal coincidence of some long GRBs with type Ic supernovae. The case of binary-driven hypcrnova (BdHN) assumes a close system, which starts as an evolved core - neutron star binary. After the core-collapse event, the new NS - black hole system is formed, emitting the GRB in the process. We performed the time-resolved and time-integrated analysis of the Fermi data. Preliminary results gave isotropic energy Eiso = 6.05 × 1053 erg and the total P-GRB energy of Ep–GRB = 3.7 × 1052 erg. At transparency point we found a Lorentz factor Γ ~ 2.17 × 103 laboratory radius of 8.33 x 1013 cm, P-GRB observed temperature of 168 keV and a baryon load B = 4.35 × 10-4. Simulated light-curve and prompt emission spectra showed the average circum burst medium density to be n ~ 0.03 particles per cm3. We reproduced the X-ray light-curve within the rest-frame of the source, finding the common late power-law behavior, with α = –1.22. Considering these results, we interpret GRB 110731A as a member of a BdHNe group

What can we learn from GRBs?

We review our recent results on the classification of long and short gamma-ray bursts (GRBs) in different subclasses. We provide observational evidences for the binary nature of GRB progenitors. For long bursts the induced gravitational collapse (IGC) paradigm proposes as progenitor a tight binary system composed of a carbon-oxygen core (COcore) and a neutron star (NS) companion; the supernova (SN) explosion of the COcore triggers a hypercritical accretion process onto the companion NS. For short bursts a NS–NS merger is traditionally adopted as the progenitor. We also indicate additional sub-classes originating from different progenitors: (COcore)–black hole (BH), BH–NS, and white dwarf–NS binaries. We also show how the outcomes of the further evolution of some of these sub-classes may become the progenitor systems of other sub-classes