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We present 22 new (+3 confirmed) cataclysmic variables (CVs) in the non core-collapsed globular cluster 47 Tucanae (47 Tuc). The total number of CVs in the cluster is now 43, the largest sample in any globular cluster so far. For the…

In this study, we investigate the contribution of millisecond pulsars (MSPs) to the gamma-ray excess observed in the Galactic Center by analyzing data from high-resolution direct N-body simulations of six globular clusters (GCs) that…

High Energy Astrophysical Phenomena · Physics 2024-10-22 Dana Kuvatova , Taras Panamarev , Maryna Ishchenko , Anton Gluchshenko , Peter Berczik

A Chandra ACIS-S imaging observation of the nearby galaxy M81 (NGC 3031) reveals 9 luminous soft X-ray sources. The local environments, X-ray spectral properties, and X-ray light curves of the sources are presented and discussed in the…

Astrophysics · Physics 2009-11-07 Douglas Swartz , Kajal Ghosh , Valery Suleimanov , Allyn Tennant , Kinwah Wu

We present the results of a search for diffuse x-ray sources in a 65 ksec ROSAT PSPC exposure of 47 Tuc. There is faint, soft emission on the NE side of the cluster at a distance of 6 arcmin from the core. The location of this emission…

Astrophysics · Physics 2009-10-28 Martin Krockenberger , J. Grindlay

The recent Fermi detection of the globular cluster (GC) 47 Tucanae highlighted the importance of modeling collective gamma-ray emission of millisecond pulsars (MSPs) in GCs. Steady flux from such populations is also expected in the very…

High Energy Astrophysical Phenomena · Physics 2011-02-11 C. Venter , O. C. de Jager , A. -C. Clapson

We know from observations that globular clusters are very efficient catalysts in forming unusual short-period binary systems or their offspring, such as low-mass X-ray binaries (LMXBs; neutron stars accreting matter from low-mass stellar…

We present VLT (FORS1) photometry of the lower main sequence (MS) of the Galactic Globular Cluster (GGC) NGC 6397, for stars located in 2 fields extending from a region near the cluster center out to ~ 10'. The obtained CMD shows a narrow…

Astrophysics · Physics 2007-05-23 G. Andreuzzi , V. Testa , G. Marconi , G. Alcaino , F. Alvarado , R. Buonanno

Dynamical interactions that occur between objects in dense stellar systems are particularly important for the question of formation of X-ray binaries. We present results of numerical simulations of 70 globular clusters with different…

Astrophysics · Physics 2009-11-13 Natalia Ivanova , Craig O. Heinke , Frederic A. Rasio

This paper is the second in a series where we report the results of the long-term timing of the millisecond pulsars (MSPs) in 47 Tucanae with the Parkes 64-m radio telescope. We obtain improved timing parameters that provide additional…

High Energy Astrophysical Phenomena · Physics 2018-04-03 P. C. C. Freire , A. Ridolfi , M. Kramer , C. Jordan , R. N. Manchester , P. Torne , J. Sarkissian , C. O. Heinke , N. D'Amico , F. Camilo , D. R. Lorimer , A. G. Lyne

Using archival spectral-imaging data with a total exposure of $\sim144$ ks obtained by {\it Chandra}, 43 X-ray sources are detected within the half-light radius of globular cluster M62 (NGC6266). Based on the X-ray colour-luminosity diagram…

High Energy Astrophysical Phenomena · Physics 2020-09-01 Kwangmin Oh , C. Y. Hui , K. L. Li , A. K. H. Kong

In the third Fermi catalogue (3FGL) there are sixteen gamma-ray globular clusters. After analyzing the recent released Pass 8 data of Fermi Large Area Telescope (LAT), we report the discovery of significant gamma-ray emission from M 15 and…

High Energy Astrophysical Phenomena · Physics 2016-03-23 P. F. Zhang , Y. L. Xin , L. Fu , J. N. Zhou , J. Z. Yan , Q. Z. Liu , L. Zhang

The 80 high-mass X-ray binary (HMXB) pulsars that are known to reside in the Magellanic Clouds (MCs) have been observed by the XMM-Newton and Chandra X-ray telescopes on a regular basis for 15 years, and the XMM-Newton and Chandra archives…

High Energy Astrophysical Phenomena · Physics 2017-06-14 Dimitris M. Christodoulou , Silas G. T. Laycock , Jun Yang , Samuel Fingerman

We present the first X-ray observations of three recently discovered millisecond pulsars (MSPs) with interesting characteristics: PSR J0337+1715, PSR J0636+5129, and PSR J0645+5158. PSR J0337+1715 is a fast-spinning, bright, and so-far…

We present the results of recent Arecibo and Green Bank observations of the globular cluster NGC 6760. Using Arecibo, a phase-coherent timing solution has been obtained for the previously known binary pulsar in this cluster, PSR…

We report on 40 kiloseconds of ROSAT HRI observations of the globular cluster M92 (NGC 6341) and 20 kiloseconds of observations of the globular cluster M13 (NGC 6205). We find that the low-luminosity (10^{32.5} erg/sec at 7.5 kpc) source…

Astrophysics · Physics 2015-06-24 D. Fox , W. Lewin , B. Margon , J. van Paradijs , F. Verbunt

In this paper we review the recent discovery of several millisecond pulsars (MSPs) in eccentric binary systems. Timing these MSPs we were able to estimate (and in one case precisely measure) their masses. These results suggest that, as a…

Solar and Stellar Astrophysics · Physics 2009-07-21 Paulo C. C. Freire

We report the detection of six discrete, low-luminosity (Lx < 10^33 erg/s) X-ray sources, located within 12 arcsec of the center of the collapsed-core globular cluster M30 (NGC 7099), and a total of 13 sources within the half-mass radius,…

We report the discovery of five new millisecond pulsars in the globular cluster NGC 6440 and three new ones in NGC 6441; each cluster has one previously known pulsar. Four of the new pulsars are found in binary systems. One of the new…

This paper describes the new Globular Clusters GMRT Pulsar Search (GCGPS) survey. This survey aims to find MSPs in the globular clusters (GCs) of the Milky Way using uGMRT. The observations use the uGMRT's Band-4 (550$-$750 MHz) and Band-3…

Using data from the HAWC gamma-ray Telescope, we have studied a sample of 37 millisecond pulsars (MSPs), selected for their spindown power and proximity. From among these MSP, we have identified four which favor the presence of very…

High Energy Astrophysical Phenomena · Physics 2022-05-25 Dan Hooper , Tim Linden
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