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A new picture of pulsar high-energy emission is proposed that is different from both the traditional polar cap and outer gap models, but combines elements of each. The slot gap model is based on electron acceleration along the edge of the…

Astrophysics · Physics 2009-11-10 Alice Harding , Alexander Muslimov

The radio emission in many pulsars show sudden changes, usually within a period, that cannot be related to the steady state processes within the inner acceleration region (IAR) above the polar cap. These changes are often quasi-periodic in…

High Energy Astrophysical Phenomena · Physics 2021-06-09 U. Geppert , R. Basu , D. Mitra , G. Melikidze , M. Szkudlarek

We determine the critical size l_crit of a filament of cold (T~10^4 K) gas that is in radiative equilibrium with X-ray emitting gas at temperatures T_out~10^6 - 10^8 K. Filaments smaller than l_crit will be rapidly evaporated, while longer…

Astrophysics · Physics 2009-11-10 Carlo Nipoti , James Binney

We present an analysis of polarized X-ray pulses based on simulated data for accreting millisecond pulsars (AMPs). We used the open-source X-ray Pulse Simulation and Inference code (previously applied to NICER observations), which we…

Starspots are ubiquitous in young, low-mass stars, yet their impact on the spectral classification and fundamental parameter inference of pre-main sequence stars (PMS) has been largely overlooked. In this study, we demonstrate that cool…

Solar and Stellar Astrophysics · Physics 2025-07-30 Facundo Pérez Paolino , Jeff Bary , Benjamin Horner , Lynne A. Hillenbrand , Adolfo Carvalho

We model the temperature distribution at the surface of a magnetized neutron star and study the effects on the observable X-ray spectra and light curves, taking fully into account gravitational lensing. Only dipolar fields are considered…

Astrophysics · Physics 2009-10-22 Dany Page

We show that the soft X-ray spectra and light curves observed with the ROSAT and EUVE from the closest known millisecond pulsar J0437--4715 can be interpreted as thermal radiation from two hot polar caps whose emitting layers (atmospheres)…

Astrophysics · Physics 2008-02-03 V. E. Zavlin , G. G Pavlov

Superflares on the solar type stars observed by \textit{Kepler} demonstrate the contrast in the optical continuum of the order 0.1--1 per cent. The mechanism of formation of this radiation is not firmly established. We consider a model…

Solar and Stellar Astrophysics · Physics 2020-04-09 B. A. Nizamov

PSR J0108$-$1431 is an old pulsar where the X-ray emission is expected to have a thermal component from the polar cap and a non-thermal component from the magnetosphere. Although the phase-integrated spectra are fit best with a single…

High Energy Astrophysical Phenomena · Physics 2019-09-04 Prakash Arumugasamy , Dipanjan Mitra

We complete our study of pulsars' non-uniform surface temperature and of its effects on their soft X-ray thermal emission. Our previous work had shown that, due to gravitational lensing, dipolar fields cannot reproduce the strong pulsations…

Astrophysics · Physics 2009-10-28 Dany Page , Antonio Sarmiento

Many of the most luminous extragalactic radio sources are located at the centers of X-ray clusters, and so their radiation must be scattered by the surrounding hot gas. We show that radio observations of the highly-polarized scattered…

Astrophysics · Physics 2009-11-07 Gilbert Holder , Abraham Loeb

We continue the study of the effects of a strong magnetic field on the temperature distribution in the crust of a magnetized neutron star (NS) and its impact on the observable surface temperature. Extending the approach initiated in Geppert…

Astrophysics · Physics 2009-11-11 U. Geppert , M. Kueker , Dany Page

Previous analyses of ASCA data of clusters of galaxies have found conflicting results regarding the slope of the temperature profile of the hot X-ray gas within clusters, mainly because of the large, energy-dependent point spread function…

Astrophysics · Physics 2009-10-31 Jimmy A. Irwin , Joel N. Bregman , August E. Evrard

A novel scheme has been developed to show that the observed phase behaviour associated with subpulse drifting from two pulsars, J1034$-$3224 and J1720$-$2933, can be used to obtain the magnetic field configuration in the partially screened…

High Energy Astrophysical Phenomena · Physics 2023-05-24 Rahul Basu , Dipanjan Mitra , George I. Melikidze

Thermal radiation from hot polar caps is examined in radio pulsars with drifting subpulses. It is argued that if these subpulses correspond to sparking discharges of the inner acceleration region right above the polar cap surface then a…

Astrophysics · Physics 2007-05-23 Janusz Gil , George Melikidze , Bing Zhang

We present a temperature and a magnetic-field surface map of the K2 subgiant of the active binary II Peg. Employed are high resolution Stokes IV spectra obtained with the new Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI)…

Solar and Stellar Astrophysics · Physics 2019-05-15 K. G. Strassmeier , T. A. Carroll , I. V. Ilyin

Radio observations from normal pulsars indicate that the coherent radio emission is excited by curvature radiation from charge bunches. In this review we provide a systematic description of the various observational constraints on the radio…

High Energy Astrophysical Phenomena · Physics 2024-06-03 Dipanjan Mitra , Rahul Basu , George I Melikizde

I present an analysis of the deepest X-ray exposure of a radio millisecond pulsar (MSP) to date, an X-ray Multi Mirror-Newton European Photon Imaging Camera spectroscopic and timing observation of the nearest known MSP, PSR J0437--4715. The…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Slavko Bogdanov

We propose a model, which naturally explains an unusual thermal X-ray emission, observed from PSR J1119-6127. The model is based on the assumption that the pulsar magnetic field near the stellar surface differs significantly from the pure…

Astrophysics · Physics 2007-05-23 G. I. Melikidze , J. Gil , A. Szary

The radio-quiet pulsar PSR J2021+4026 is mostly known because it is the only rotation-powered pulsar that shows variability in its {\gamma}-ray emission. Using XMM-Newton archival data, we first confirmed that its flux is steady in the…

High Energy Astrophysical Phenomena · Physics 2021-02-17 Michela Rigoselli , Sandro Mereghetti , Roberto Taverna , Roberto Turolla , Davide De Grandis