Related papers: Estimates for Very High Energy Gamma Rays from Glo…
Observations of the globular cluster 47 Tucanae (NGC 104), which contains at least 23 millisecond pulsars, were performed with the H.E.S.S. telescope system. The observations lead to an upper limit of F(E>800 GeV) < 6.7e-13 / cm^2 s on the…
Globular clusters (GCs) are established emitters of high-energy (HE, 100 MeV<E<100 GeV) \gamma-ray radiation which could originate from the cumulative emission of the numerous millisecond pulsars (msPSRs) in the clusters' cores or from…
We combined Chandra ACIS observations of the globular cluster 47 Tucanae (hereafter, 47 Tuc) from 2000, 2002, and 2014-15 to create a deeper X-ray source list, and study some of the faint radio millisecond pulsars (MSPs) present in this…
If millisecond pulsars (MSPs) are responsible for the excess gamma-ray emission observed from the region surrounding the Galactic Center, the same region should also contain a large population of low-mass X-ray binaries (LMXBs). In this…
Our Chandra X-ray observation of the globular cluster 47 Tuc clearly detected most of the 16 MSPs with precise radio positions, and indicates probable X-ray emission from the remainder. The MSPs are soft (BB kT 0.2-0.3 keV) and faint (Lx…
A significant fraction of millisecond pulsars (MSPs) in globular clusters (GCs) are observed as isolated objects, despite the widely accepted scenario in which MSPs are formed through recycling in compact binary systems. The origin of these…
We present a comprehensive census of X-ray millisecond pulsars (MSPs) in 29 Galactic globular clusters (GCs), including 68 MSPs with confirmed X-ray luminosities and 107 MSPs with X-ray upper limits. We compile previous X-ray studies of GC…
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…
We report the discovery of peculiar X-ray spectral variability in the binary radio millisecond pulsar PSR J0024--7204W in the globular cluster 47 Tucanae. The observed emission consists of a dominant non-thermal component, which is eclipsed…
We have monitored a sample of 27 nearby globular clusters in the hard X-ray band (20-120 keV) for approximately 1400 days using the BATSE instrument on board the Compton Gamma-Ray Observatory. Globular clusters may contain a large number of…
We have detected 300 X-ray sources within the half-mass radius (2.79') of the globular cluster 47 Tucanae in a deep (281 ks) Chandra exposure. We perform photometry and simple spectral fitting for our detected sources, and construct…
We combine new and archival Chandra observations of the globular cluster NGC 6752 to create a deeper X-ray source list, and study the faint radio millisecond pulsars (MSPs) of this cluster. We detect four of the five MSPs in NGC 6752, and…
We have performed a systematic study of the rotational, orbital and X-ray properties of millisecond pulsars (MSPs) in globular clusters (GCs) and compared their nature with those of the MSPs in the Galactic field (GF). We found that GC MSPs…
Globular clusters (GCs) are astronomical tapestries embroidered with an abundance of exotic stellar-type objects. Their high age promises a rich harvest of evolved stellar products, while the deep potential wells and high mass densities at…
Millisecond Pulsars (MSPs) are fast rotating, highly magnetized neutron stars. According to the "canonical recycling scenario", MSPs form in binary systems containing a neutron star which is spun up through mass accretion from the evolving…
Globular clusters are known to harbour a significant population of neutron star X-ray binaries that could be responsible for delaying the inevitable core collapse of these dense clusters. As a result, their progeny, namely millisecond…
The lack of detected pulsars at the Galactic Center (GC) region is a long-standing mystery. We argue that the high stellar density in the central parsec around the GC is likely to result in a pulsar population dominated by millisecond…
Despite considerations of mass loss from stellar evolution suggesting otherwise, the content of gas in globular clusters seems poor and hence its measurement very elusive. One way of constraining the presence of ionized gas in a globular…
We summarize the x-ray properties of the complete samples of millisecond pulsars (MSPs) detected in our Chandra observations of the globular clusters 47 Tuc and NGC 6397. The 47 Tuc MSPs are predominantly soft sources suggestive of thermal…
In recent years, X-ray observations with Chandra and XMM-Newton have significantly increased our understanding of rotation-powered (radio) millisecond pulsars (MSPs). Deep Chandra studies of several globular clusters have detected X-ray…