We present multiband observations and analysis of EP240801a, a low-energy, extremely soft gamma-ray burst (GRB) discovered on 2024 August 1 by the Einstein Probe (EP) satellite with a weak contemporaneous signal also detected by the Fermi Gamma-ray Burst Monitor (GBM). Optical spectroscopy of the afterglow, obtained by Gran Telescopio Canarias and Keck, identified the redshift of z = 1.6734. EP240801a exhibits a burst duration of 148 s in X-rays and 22.3 s in gamma rays, with X-rays leading by 80.61 s. Spectral lag analysis indicates that the gamma-ray signal arrived 8.3 s earlier than the X-rays. Joint spectral fitting of EP Wide-field X-ray Telescope and Fermi/GBM data yields an isotropic energy E γ , iso = ( 5.5 7 − 0.50 + 0.54 ) × 1 0 51 erg , a peak energy E peak = 14.9 0 − 4.71 + 7.08 keV , and a fluence ratio S(25–50 keV)/S ( 50 – 100 keV ) = 1.6 7 − 0.46 + 0.74 , classifying EP240801a as an X-ray flash (XRF). The host-galaxy continuum spectrum, inferred using Prospector, was used to correct its contribution for the observed outburst optical data. Unusual early R-band behavior and EP Follow-up X-ray Telescope observations suggest multiple components in the afterglow. Three models are considered: a two-component jet model, a forward-reverse shock model, and a forward shock model with energy injection. All three provide reasonable explanations. The two-component jet model and the energy injection model imply a relatively small initial energy and velocity of the jet in the line of sight, while the forward-reverse shock model remains typical. Under the two-component jet model, EP240801a may resemble GRB 221009A (BOAT) if the bright narrow beam is viewed on-axis. Therefore, EP240801a can be interpreted as an off-beam (narrow) jet or an intrinsically weak GRB jet. Our findings provide crucial clues for uncovering the origin of XRFs.

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.

We present full photometric coverage and spectroscopic data for soft GRB 201015A with a redshift z = 0.426. Our data spans a time range of 85 days following the detection of GRB. These observations revealed an underlying supernova SN 201015A with a maximum at 8.54 ±1.48 days (rest frame) and an optical peak absolute magnitude |$-19.45_{-0.47}^{+0.85}$| mag. The supernova stands out clearly, since the contribution of the afterglow at this time is not dominant, which made it possible to determine SN’s parameters. A comparison of these parameters reveals that the SN 201015A is the earliest (the minimum T_max) known supernova associated with gamma-ray bursts. Spectroscopic observations during the supernova decay stage showed broad lines, indicating a large photospheric velocity, and identified this supernova as a type Ic-BL. Thus, the SN 201015A associated with the GRB 201015A becomes the 27th SN/GRB confirmed by both photometric and spectroscopic observations. Using the results of spectral analysis based on the available data of Fermi-GBM experiment, the parameters E_{p, i} = 20.0 ± 8.5 keV and E_iso = (1.1 ± 0.2) × 10⁵⁰ erg were obtained. According to the position of the burst on the E_{p, i}–E_iso correlation, GRB 201015A was classified as a Type II (long) gamma-ray burst, which was also confirmed by the T_{90, i}–EH diagram.

The point X-ray source 1E 161348-5055 is observed to display pulsations with the period 6.67 hr and \(|\dot{P}| \leq1.6 \times10^{-9}\,{\rm s\,s^{-1}}\). It is associated with the supernova remnant RCW 103 and is widely believed to be a ∼2000 yr old neutron star. Observations give no evidence for the star to be a member of a binary system. Nevertheless, it resembles an accretion-powered pulsar with the magnetospheric radius ∼3000 km and the mass-accretion rate \(\sim 10^{14}\,{\rm g\,s^{-1}}\). This situation could be described in terms of accretion from a (residual) fossil disk established from the material falling back towards the star after its birth. However, current fall-back accretion scenarios encounter major difficulties explaining an extremely long spin period of the young neutron star. We show that the problems can be avoided if the accreting material is magnetized. The star in this case is surrounded by a fossil magnetic slab in which the material is confined by the magnetic field of the accretion flow itself. We find that the surface magnetic field of the neutron star within this scenario is ∼10¹² G and that a presence of \(\gtrsim10^{-7}\,{\rm M_{\odot}}\) magnetic slab would be sufficient to explain the origin and current state of the pulsar.

The persistent X-ray pulsar OAO 1657-415 is associated with a wind-fed High Mass X-ray Binary system and shows a peculiar spin evolution. On a timescale of more than 30 years it is observed to experience a regular spin-up which is superposed on episodic and chaotic variations of the period at a very high rate. We explore a possibility to explain the spin evolution of the pulsar in terms of Magnetic Levitation Accretion scenario in which the neutron star captures material from a magnetized stellar wind of its massive companion and accretes matter from a non-Keplerian magnetized disk (Magnetic Levitating disk or ML-disk). We show this scenario to be applicable if the magnetic field in the wind at a distance of binary separation lies in the interval 20 – 70 mG.

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 ($B_{\mathrm{ns}}$) for a population of known neutron stars in the radio pulsar (ejector) stage. The evaluated $B_{\mathrm{ns}}\left(\beta \right)$ may differ by an order of magnitude from the values without considering the angle $\beta$. It is shown that $B_{\mathrm{ns}}\left(\beta \right)$ lies in the range ${10}^8$–${10}^{14}\mathrm{G}$ for a known population of short and middle periodic radio pulsars.