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The hard X-ray source SAX J0635+0533 shows pulsations at a period of 33.8 ms and is thought to be associated with a bright Be star. We here report on radio observations towards this source with the VLA and Arecibo radiotelescopes. With the…

Astrophysics · Physics 2007-05-23 L. Nicastro , B. M. Gaensler , M. A. McLaughlin

AX J0049.4-7323 is a Be/X-ray binary that shows an unusual and poorly understood optical variability that consists of periodic and bright optical outbursts, simultaneous with X-ray outbursts, characterised by a highly asymmetric profile.…

High Energy Astrophysical Phenomena · Physics 2019-01-23 L. Ducci , C. Malacaria , P. Romano , L. Ji , E. Bozzo , I. Saathoff , A. Santangelo , A. Udalski

Pravdo et al (1997) claimed that the phase resolved x-ray spectrum in Crab pulsar (PSR B0531+21) shows a spectral hardening at the leading edge of the first peak of its integrated profile; this was a new and unexpected result. This article…

Astrophysics · Physics 2009-11-07 M. Vivekanand

On September 21, 2006, an intense (~10^39 erg/s) and short (20 ms) burst was detected by Swift BAT at a position consistent with that of the candidate Anomalous X-ray Pulsar, CXOU J164710.2-455216, discovered by Chandra in 2005. Swift…

Astrophysics · Physics 2011-02-11 G. L. Israel , S. Campana , S. Dall'Osso , M. P. Muno , J. Cummings , R. Perna , L. Stella

We presented a comprehensive multi-epoch timing and multiwavelength analysis of the accreting millisecond X-ray pulsar MAXI J1957+032, covering two major outbursts in 2022 and 2025. By reanalyzing the 2022 outburst data from the Neutron…

Aims: We investigate the X-ray spectral and timing properties of the high mass X-ray binary EXO 2030+375 observed during its June-September 2006 giant (type II) outburst. Methods: The data analyzed in this work are from partly simultaneous…

We studied the millihertz quasi-periodic oscillation (mHz QPO) in the 2020 outburst of the Be/X-ray binary 1A 0535+262 using Insight-HXMT data over a broad energy band. The mHz QPO is detected in the 27-120 keV energy band. The QPO centroid…

VERITAS observed the bright blazar 1ES 2344+514 during two flaring periods, one from Dec. 17 to Dec. 18, 2015 (MJD 57373-57374) with a peak flux of ~60% of the Crab and another from Nov. 28 to Dec. 3, 2021 (MJD 59546-59551) with a peak flux…

High Energy Astrophysical Phenomena · Physics 2023-09-21 Connor Poggemann , Jodi Christiansen

We analyzed four epochs of beamformed EVN data of the Crab Pulsar at 1658.49 MHz. With the high sensitivity resulting from resolving out the Crab Nebula, we are able to detect even the faint high-frequency components in the folded profile.…

High Energy Astrophysical Phenomena · Physics 2023-09-18 Rebecca Lin , Marten H. van Kerkwijk

The first near-side X-class flare of the Solar Cycle 24 occurred in February 2011 and produced a very strong seismic response in the photosphere. One sunquake was reported by Kosovichev (2011) followed by the discovery of a second sunquake…

Solar and Stellar Astrophysics · Physics 2015-06-11 S. Zharkov , L. M. Green , S. A. Matthews , V. V. Zharkova

Accretion onto magnetized neutron stars is expected to be centrifugally inhibited at low accretion rates. Several sources, however, are known to pulsate in quiescence at luminosities below the theoretical limit predicted for the onset of…

High Energy Astrophysical Phenomena · Physics 2013-12-02 Victor Doroshenko , Andrea Santangelo , Rozaliya Doroshenko , Isabel Caballero , Sergej Tsygankov , Richard Rothschild

We present results from AstroSat observation of the recent outburst of GRO J2058+42, an X-ray pulsar in a Be-binary system. The source was observed on April 10, 2019 by LAXPC and SXT instruments on AstroSat during its declining phase of the…

High Energy Astrophysical Phenomena · Physics 2020-07-15 Kallol Mukerjee , H. M. Antia , Tilak Katoch

We present the X-ray light curves of the last two outbursts --2014 & 2016-- of the well known accreting millisecond X-ray pulsar (AMXP) Aquila X-1 using the monitor of all sky X-ray image (MAXI) observations in the $2-20$ keV band. After…

High Energy Astrophysical Phenomena · Physics 2017-04-11 Can Güngör , Kazım Yavuz Ekşi , Ersin Göğüş

We have observed the pulsar in the Crab Nebula at high radio frequencies and high time resolution. We present continuously sampled data at 640-ns time resolution, and individual bright pulses recorded at down to 0.25-ns time resolution.…

High Energy Astrophysical Phenomena · Physics 2015-06-23 T. H. Hankins , G. Jones , J. A. Eilek

VER J0521+211 (RGB J0521.8+2112) is one of the brightest and most powerful blazars detected in the TeV gamma-ray regime. It is located at a redshift of z=0.108 and since its discovery in 2009, VER J0521+211 has exhibited an average TeV flux…

High Energy Astrophysical Phenomena · Physics 2019-08-15 Heike Prokoph , Paolo Da Vela , Cornelia Schultz

We present results from a study of broadband timing and spectral properties of EXO 2030+375 using a Suzaku observation. Pulsations with a period of 41.41 s and strong energy dependent pulse profiles were clearly detected up to ~100 keV.…

High Energy Astrophysical Phenomena · Physics 2013-02-06 Sachindra Naik , Chandreyee Maitra , Gaurava K. Jaisawal , Biswajit Paul

We present the largest sample of type-I (thermonuclear) X-ray bursts yet assembled, comprising 7083 bursts from 85 bursting sources. The sample is drawn from observations with Xenon-filled proportional counters on the long-duration…

High Energy Astrophysical Phenomena · Physics 2020-08-14 D. K. Galloway , J. J. M. in 't Zand , J. Chenevez , H. Wörpel , L. Keek , L. Ootes , A. L. Watts , L. Gisler , C. Sanchez-Fernandez , E. Kuulkers

We present temporal analysis of the three outbursts of the X-ray millisecond pulsar SAX J1808.4-3658 that occurred in 1998, 2000 and 2002. With a technique that uses the chi^2 obtained with an epoch folding search to discriminate between…

Astrophysics · Physics 2009-11-11 A. Papitto , M. T. Menna , L. Burderi , T. Di Salvo , F. D' Antona , N. R. Robba

The Small Magellanic Cloud (SMC) Be/X-ray binary pulsar SXP6.85 = XTE J0103-728 underwent a large Type II outburst beginning on 2008 August 10. The source was consistently seen for the following 20 weeks (MJD = 54688 - 54830). We present…

High Energy Astrophysical Phenomena · Physics 2015-05-14 L. J. Townsend , M. J. Coe , V. A. McBride , A. J. Bird , M. P. E. Schurch , R. H. D. Corbet , F. Haberl , J. L. Galache , A. Udalski

Our goal is to investigate the X-ray timing and spectral variability of the high-mass X-ray binary 1A 1118-615 during a type-II outburst. We performed a detailed color, spectral and timing analysis of a giant outburst from 1A 1118-615,…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Elisa Nespoli , Pablo Reig