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Motivated by the recent discovery of 30 new millisecond pulsars in Terzan 5, made using the Green Bank Telescope's S-band receiver and the Pulsar Spigot spectrometer, we have set out to use the same observing system in a systematic search…

Binaries in the cores of globular clusters are known to prevent the gravitational collapse of the cluster, and simulations predict that the core of NGC 6397 contains a large number of white dwarfs (WDs), of which many are expected to be…

Solar and Stellar Astrophysics · Physics 2026-03-18 Fabian Göttgens , Marilyn Latour , Ulrich Heber , Sebastian Kamann , Kyle Kremer , Sven Martens , Stefan Dreizler

Using hundreds of XMM-Newton and Chandra archival observations and nearly a thousand RXTE observations, we have generated a comprehensive library of the known pulsars in the Small and Large Magellanic Clouds (SMC, LMC). The pulsars are…

High Energy Astrophysical Phenomena · Physics 2017-03-16 J. Yang , S. G. T. Laycock , J. J. Drake , M. J. Coe , S. Fingerman , J. Hong , V. Antoniou , A. Zezas

We report on the follow-up observations of circularly polarized sources identified in the MeerKAT image-based survey of the Galactic bulge. Using the Parkes radio telescope, we observed sixteen circularly polarized sources with the UWL…

High Energy Astrophysical Phenomena · Physics 2026-03-17 Rahul Sengar , Akash Anumarlapudi , David L. Kaplan , Dale A. Frail , Scott D. Hyman , Emil Polisensky

Galactic globular clusters harbour binary systems that are detected as faint X-ray sources. These close binaries are thought to play an important role in the stability of the clusters by liberating energy and delaying the inevitable core…

Astrophysics · Physics 2009-11-13 M. Servillat , N. A. Webb , D. Barret

We analyse a Chandra observation of the rich globular cluster NGC 362, finding 33 X-ray sources within 1' (1.2 half-mass radii) of the cluster center. Spectral analysis of the brightest source (X1) shows blackbody-like emission, indicating…

High Energy Astrophysical Phenomena · Physics 2024-03-26 Gourav Kumawat , Craig O. Heinke , Haldan N. Cohn , Phyllis M. Lugger

Although only 22 millisecond pulsars (MSPs) are currently known to exist in the globular cluster (GC) 47 Tucanae, this cluster may harbor 30-60 MSPs, or even up to ~200. In this Letter, we model the pulsed curvature radiation (CR) gamma-ray…

Astrophysics · Physics 2009-11-30 C. Venter , O. C. de Jager

Highly sensitive and precise X-ray imaging from Chandra, combined with the superb spatial resolution of HST optical images, dramatically enhances our empirical understanding of compact binaries such as cataclysmic variables and low mass…

Solar and Stellar Astrophysics · Physics 2015-05-20 Bruce Margon , B. Beck-Winchatz , L. Homer , D. Pooley , C. G. Bassa , S. F. Anderson , W. H. G. Lewin , F. Verbunt , A. K. H. Kong , R. M. Plotkin

We present a source catalog from the first deep hard X-ray ($E>10$ keV) survey of the Small Magellanic Cloud (SMC), the NuSTAR Legacy Survey of the SMC. We observed three fields, for a total exposure time of 1 Ms, along the bar of this…

We present Chandra X-ray Observatory ACIS-S3 X-ray imaging observations and VLT/FORS2 and Hubble Space Telescope optical observations of two low-density Galactic globular clusters; NGC 6366 and M55. We detect 16 X-ray sources with 0.5-6.0…

Astrophysics · Physics 2009-11-13 C. G. Bassa , D. Pooley , F. Verbunt , L. Homer , S. F. Anderson , W. H. G. Lewin

From a deep multi-epoch Chandra observation of the elliptical galaxy NGC 3379 we report the spectral properties of eight luminous LMXBs (LX>1.2E38 erg/s). We also present a set of spectral simulations, produced to aid the interpretation of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 N. J. Brassington , G. Fabbiano , S. Blake , A. Zezas , L. Angelini , R. L. Davies , J. Gallagher , V. Kalogera , D. -W. Kim , A. R. King , A. Kundu , G. Trinchieri , S. Zepf

(Abridged) We present a Chandra observation of the supernova remnant (SNR) 3C 397 (G41.1-0.3) obtained with ACIS-S. Previous studies of this SNR have shown that it harbors a central X-ray `hot spot' suggestive of a compact object associated…

Astrophysics · Physics 2014-10-13 S. Safi-Harb , G. Dubner , R. Petre , S. S. Holt , P. Durouchoux

We report on the Chandra X-ray Observatory and Hubble Space Telescope observation of two low core density globular clusters, NGC6144 and E3. By comparing the number of X-ray sources inside the half-mass radius to those outside, we found 6…

High Energy Astrophysical Phenomena · Physics 2011-02-11 Shih Hao Lan , Albert K. H. Kong , Frank Verbunt , Walter H. G. Lewin , Cees Bassa , Scott F. Anderson , David Pooley

We present rotational and astrometric parameters of three millisecond pulsars located near the center of the globular cluster NGC 6266 (M62) resulting from timing observations with the Parkes radio telescope. Their accelerations toward the…

Astrophysics · Physics 2009-11-10 A. Possenti , N. D'Amico , R. N. Manchester , F. Camilo , A. G. Lyne , J. Sarkissian , A. Corongiu

As part of an ongoing program to test Newton's law of gravity in the low acceleration regime using globular clusters, we present here new results obtained for NGC 6171. Combining VLT spectra for 107 stars with data from the literature, we…

Astrophysics · Physics 2007-05-23 Riccardo Scarpa , Gianni Marconi , Roberto Gilmozzi

We have used main-sequence fitting to calibrate the distances to the globular clusters NGC 6397, M5, NGC 288, M71 and 47 Tucanae, matching the cluster photometry against data for subdwarfs with precise Hipparcos parallax measurements and…

Astrophysics · Physics 2007-05-23 I. Neill Reid , Palomar Observatory , Caltech

We report on the detection of a soft spatially-extended component of X-ray emission around four intermediate-redshift 3C quasars observed with Chandra: 3C254, 3C263, 3C275.1 and 3C281. The bolometric luminosity of this emission ranges over…

Astrophysics · Physics 2009-09-17 C. S. Crawford , A. C. Fabian

In this article, we revisit the gamma-ray emission observed from millisecond pulsars and globular clusters. Based on 5.6 years of data from the Fermi Gamma-Ray Space Telescope, we report gamma-ray spectra for 61 millisecond pulsars, finding…

High Energy Astrophysical Phenomena · Physics 2014-07-22 Ilias Cholis , Dan Hooper , Tim Linden

The study of binary millisecond pulsars (MSPs) in globular clusters (GCs) is a key ingredient to study binary and stellar evolution under extreme conditions. In this context, an accurate analysis of the optical emission, which is mostly…

High Energy Astrophysical Phenomena · Physics 2026-01-14 Greta Ettorre , Emanuele Dalessandro , Mario Cadelano , Cristina Pallanca , Paulo C. C. Freire , Alessandro Ridolfi

We report the discovery of X-ray pulsations at 105.2 Hz (9.5 ms) from the transient X-ray binary IGR J16597-3704 using NuSTAR and Swift. The source was discovered by INTEGRAL in the globular cluster NGC 6256 at a distance of 9.1 kpc. The…