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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 have carried out a large grid of N-body simulations in order to investigate if mass-loss as a result of primordial gas expulsion can be responsible for the large fraction of second generation stars in globular clusters (GCs) with…

Astrophysics of Galaxies · Physics 2015-07-14 Pouria Khalaj , Holger Baumgardt

The wealth of high-energy (E > 50 MeV) and very-high-energy (E > 100 GeV) data accumulated over the past few years have provided unprecedented opportunities to probe pulsar emission models. The Fermi Large Area Telescope (LAT) has now…

High Energy Astrophysical Phenomena · Physics 2017-02-03 Christo Venter

The present work is devoted to the detection of monochromatic gravitational wave signals emitted by pulsars using ALLEGRO's data detector. We will present the region (in frequency) of millisecond pulsars of the globular cluster 47 Tucanae…

General Relativity and Quantum Cosmology · Physics 2012-05-15 F. G. de Oliveira , R. M. Marinho , J. G. Coelho , N. Magalhaes

Massive Star Clusters (SCs) have been proposed as additional contributors to Galactic Cosmic rays (CRs), to overcome the limitations of supernova remnants (SNRs) to reach the highest energy end of the CR spectrum. Thanks to fast mass losses…

High Energy Astrophysical Phenomena · Physics 2025-11-17 Giada Peron

Decades after the first predictions of intermediate-mass black holes (IMBHs) in globular clusters (GCs) there is still no unambiguous observational evidence for their existence. The most promising signatures for IMBHs are found in the cores…

Astrophysics of Galaxies · Physics 2015-06-05 Stefan Umbreit , Frederic A. Rasio

Metal-poor globular clusters (GCs) can provide a probe of the earliest epoch of star formation in the Universe, being the oldest stellar systems observable. In addition, young and intermediate-age low-metallicity GCs are present in external…

Astrophysics · Physics 2009-11-11 Martina Fagiolini , Gabriella Raimondo , Scilla Degl'Innocenti

The dense cores of globular clusters (GCs) are efficient environments for the production of exotic stellar populations, including millisecond pulsars (MSPs), low-mass X-ray binaries (LMXBs) and cataclysmic variables (CVs). Most of these…

Only one globular cluster (GC), 47 Tuc, has been found to contain intracluster medium, with an electron density 100 times higher than that of the ISM in its vicinity. The characteristics of this intracluster medium are closely related to GC…

The existence of dark matter (DM) is supported by various macroscopic observations, but its microscopic nature remains elusive. The Galactic Center GeV gamma-ray excess (GCE) has been a leading candidate signal for particle DM annihilation.…

High Energy Astrophysical Phenomena · Physics 2026-03-03 Ming-Yu Lei , Bei Zhou , Xiaoyuan Huang

We present a new dynamical scenario for the formation of short-period binary millisecond pulsars in globular clusters. Our work is motivated by the recent observations of 20 radio pulsars in 47 Tuc. In a dense cluster such as 47 Tuc, most…

Astrophysics · Physics 2009-10-31 Frederic A. Rasio , Eric D. Pfahl , Saul Rappaport

We present a model for the gamma-ray emission of pulsars in terms of curvature radiation by highly relativistic particles. It is shown that the injection of power-law primary particles from an outer gap and subsequent cooling by curvature…

Astrophysics · Physics 2007-05-23 A. R. Crusius-Waetzel , H. Lesch

The high stellar densities in the cores of globular clusters cause significant stellar interactions. These stellar interactions can produce close binary mass-transferring systems involving compact objects and their progeny, such as X-ray…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Arash Bahramian , Craig O. Heinke , Gregory R. Sivakoff , Jeanette C. Gladstone

The unexpected localization of the repeating FRB 20200120E to a globular cluster challenges conventional FRB models based on magnetars formed via core collapse. One alternative model suggests that FRB 20200120E is a millisecond pulsar (MSP)…

High Energy Astrophysical Phenomena · Physics 2026-05-21 R. J. van Ruiten , J. W. T. Hessels , S. Bhandari , P. Chawla , A. Gopinath , D. M. Hewitt , K. Nimmo , M. P. Snelders

Fermi has detected gamma-ray emission from eight globular clusters. We suggest that the gamma-ray emission from globular clusters may result from the inverse Compton scattering between relativistic electrons/positrons in the pulsar wind of…

High Energy Astrophysical Phenomena · Physics 2015-05-19 K. S. Cheng , D. O. Chernyshov , V. A. Dogiel , C. Y. Hui , A. K. H. Kong

Significant gamma-ray pulsations have been detected from ~40 millisecond pulsars (MSPs) using 3 years of sky-survey data from the Fermi LAT and radio timing solutions from across the globe. We have fit the radio and gamma-ray pulse profiles…

High Energy Astrophysical Phenomena · Physics 2019-08-14 T. J. Johnson , A. K. Harding , C. Venter , J. E. Grove

Globular clusters are old stellar systems which exhibit very-high stellar densities in their cores. The globular cluster Terzan 5 is characterized by a high stellar encounter rate and hosts the largest detected population of millisecond…

High Energy Astrophysical Phenomena · Physics 2019-08-14 W. Domainko , A. -C. Clapson , F. Brun , P. Eger , M. Jamrozy , M. Dyrda , N. Komin , U. Schwanke

Transitional millisecond pulsars (tMSPs) are neutron-star systems that alternate between a rotation-powered radio millisecond pulsar state and an accretion-disk-dominated low-mass X-ray binary (LMXB)-like state on multi-year timescales.…

Until now, the study of unresolved main sequence binary stars in globular clusters has been possible almost exclusively in their central regions with deep Hubble Space Telescope (HST) observations. We present the first detection of…

Solar and Stellar Astrophysics · Physics 2025-10-15 Giacomo Cordoni , Luca Casagrande , Helmut Jerjen

Using a 16.2 hr radio observation by the Australia Telescope Compact Array (ATCA) and archival Chandra data, we found $>5\sigma$ radio counterparts to 4 known and 3 new X-ray sources within the half-light radius ($r_\mathrm{h}$) of the…