<i>FERMI</i>
                    DISCOVERY OF GAMMA-RAY EMISSION FROM THE GLOBULAR CLUSTER TERZAN 5

Kong, Albert; Hui, C. Y.; Cheng, K. S.

doi:10.1088/2041-8205/712/1/l36

Cited by 70 publications

(91 citation statements)

References 25 publications

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“…In particular, our fluxes are lower by about a factor of 2, and our SED (our Fig. 2) more closely follows an exponentially cut-off model rather than the SED derived by Kong et al (2010, their Fig. 2).…”

Section: Terzansupporting

confidence: 69%

“…1FGL J1747.9−2448 has recently been studied by Kong et al (2010). Using an exponentially cut-off power law model, they obtained a spectral index of Γ = 1.9 ± 0.2, a cut-off energy of E c = 3.8 ± 1.2 GeV, and 0.1 − 10 GeV photon and energy fluxes of 2 × 10 −7 ph cm −2 s −1 and 1.2 × 10 −10 erg cm −2 s −1 , respectively.…”

Section: Terzanmentioning

confidence: 99%

“…In Terzan 5, 33 MSPs are known so far and many more are expected based on the extrapolation of the radio luminosity function (Ransom et al 2005). Indeed, by comparing the total radio luminosity of Terzan 5 to the radio luminosity function of field pulsars, Fruchter & Goss (2000) estimate the number of pulsars in the cluster to be 60-200, and also Kong et al (2010) estimate that the number of pulsars in Terzan 5 could be as large as ∼200. For NGC 6440, Freire et al (2008) estimate that it may house as many pulsars as Terzan 5, a prediction that is compatible with our observations.…”

Section: Expected Msp Populationsmentioning

confidence: 99%

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A population of gamma-ray emitting globular clusters seen with theFermiLarge Area Telescope

Abdo¹,

Ackermann²,

Ajello³

et al. 2010

A&A

158

170

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Context. Globular clusters with their large populations of millisecond pulsars (MSPs) are believed to be potential emitters of high-energy gammaray emission. The observation of this emission provides a powerful tool to assess the millisecond pulsar population of a cluster, is essential for understanding the importance of binary systems for the evolution of globular clusters, and provides complementary insights into magnetospheric emission processes. Aims. Our goal is to constrain the millisecond pulsar populations in globular clusters from analysis of gamma-ray observations. Methods. We use 546 days of continuous sky-survey observations obtained with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope to study the gamma-ray emission towards 13 globular clusters. Results. Steady point-like high-energy gamma-ray emission has been significantly detected towards 8 globular clusters. Five of them (47 Tucanae, Omega Cen, NGC 6388, Terzan 5, and M 28) show hard spectral power indices (0.7 < Γ < 1.4) and clear evidence for an exponential cut-off in the range 1.0−2.6 GeV, which is the characteristic signature of magnetospheric emission from MSPs. Three of them (M 62, NGC 6440 and NGC 6652) also show hard spectral indices (1.0 < Γ < 1.7), however the presence of an exponential cut-off can not be unambiguously established. Three of them (Omega Cen, NGC 6388, NGC 6652) have no known radio or X-ray MSPs yet still exhibit MSP spectral properties. From the observed gamma-ray luminosities, we estimate the total number of MSPs that is expected to be present in these globular clusters. We show that our estimates of the MSP population correlate with the stellar encounter rate and we estimate 2600−4700 MSPs in Galactic globular clusters, commensurate with previous estimates. Conclusions. The observation of high-energy gamma-ray emission from globular clusters thus provides a reliable independent method to assess their millisecond pulsar populations.

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Section: Terzansupporting

confidence: 69%

Section: Terzanmentioning

confidence: 99%

Section: Expected Msp Populationsmentioning

confidence: 99%

See 1 more Smart Citation

A population of gamma-ray emitting globular clusters seen with theFermiLarge Area Telescope

Abdo¹,

Ackermann²,

Ajello³

et al. 2010

A&A

158

170

View full text Add to dashboard Cite

show abstract

“…The γ-ray spectrum of the source is best fitted by a power law with an exponential cut-off at a few GeV, as expected for a population of msPSRs. Kong et al (2010) also report tentative evidence of a second component in the γ-ray spectrum at energies above 10 GeV, which they interpret as inverse Compton (IC) up-scattering of cluster stellar photons by highenergy electrons. These observations clearly point to a considerable population of non-thermal particles in Terzan 5.…”

Section: Introductionmentioning

confidence: 93%

Multi-wavelength environment of the Galactic globular cluster Terzan 5

Clapson

Domainko

Jamrozy

et al. 2011

A&A

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Terzan 5 is a Galactic globular cluster exhibiting prominent X-ray and gamma-ray emission. Following the discovery of extended X-ray emission in this object, we explore here archival data at several wavelengths for other unexpected emission features in the vicinity of this globular cluster. Radio data from the Effelsberg 100-m telescope show several extended structures near Terzan 5, albeit with large uncertainties in the flux estimates and no reliable radio spectral index. In particular, a radio source extending from the location of Terzan 5 to the north-west could result from long-term non-thermal electron production by the large population of milli-second pulsars in this globular cluster. Another prominent radio structure close to Terzan 5 may be explained by ionised material produced by a field O star. As for the diffuse X-ray emission found in Terzan 5, its extension appears to be limited to within 2.5 arcmin of the globular cluster and the available multi-wavelength data is compatible with an inverse Compton scenario but disfavours a nonthermal Bremsstrahlung origin.

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“…Since only around 60 MSPs were known in the Galaxy outside of globular clusters before Fermi launch, Fermi has significantly contributed to the recent increase in this population, which now numbers over 200. Fermi-LAT has also detected γ rays from several globular clusters [44,45,46] that are known to host large numbers of MSPs. It was conjectured that the γ-ray flux be due to the combined pulsed emission from their MSPs.…”

mentioning

confidence: 99%

Gamma-ray pulsars: A gold mine

Grenier

Harding

2015

Comptes Rendus. Physique

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The most energetic neutron stars, powered by their rotation, are capable of producing pulsed radiation from the radio up to γ rays with nearly TeV energies. These pulsars are part of the universe of energetic and powerful particle accelerators, using their uniquely fast rotation and formidable magnetic fields to accelerate particles to ultra-relativistic speed. The extreme properties of these stars provide an excellent testing ground, beyond Earth experience, for nuclear, gravitational, and quantum-electrodynamical physics. A wealth of γ-ray pulsars has recently been discovered with the Fermi Gamma-Ray Space Telescope. The energetic γ rays enable us to probe the magnetospheres of neutron stars and particle acceleration in this exotic environment. We review the latest developments in this field, beginning with a brief overview of the properties and mysteries of rotation-powered pulsars, and then discussing γ-ray observations and magnetospheric models in more detail. RésuméLes pulsars γ : une mine d'or : Lesétoilesà neutrons les plus puissantes, qui tirent leurénergie de leur rotation, sont capables d'émettre des impulsions lumineuses des ondes radio jusqu'aux rayons γ d'énergies proches du TeV. Ces pulsars font partie des puissants accélérateurs de particules de l'Univers, profitant de leur rotation unique et de leur formidable champ magnétique pour accélérer des particules jusqu'à des vitesses ultra-relativistes. Les propriétés extrêmes de cesétoiles permettent de tester la physique nucléaire, la gravitation et l'électrodynamique quantique dans des conditions inaccessibles sur Terre. Le télescope gamma spatial Fermi vient de révéler un richeéchantillon de pulsars γ. Leur rayonnement γénergétique permet de sonder la magnétosphère desétoilesà neutrons et d'étudier l'accélération de particules dans cet environnement exotique. Nous présentons les derniers développements de ce domaine, en commençant par une rapide revue des propriétés et mystères soulevés par ces pulsars, puis en détaillant plus avant les observations γ et les modèles magnétosphériques.Keywords : pulsar ; neutron star ; magnetosphere ; gamma rays ; acceleration Mots-clés : pulsar ;étoileà neutrons ; magnétosphère ; rayons gamma ; accélération Neutron stars, pulsars, and their puzzlesA neutron star is an extreme object in many regards. It is a compact, rapidly spinning, highly magnetized star, formed from the core of a massive star which runs out of nuclear power and collapses under its own gravity, with 53 radio-loud and γ-loud young pulsars (orange upward triangles), 37 radio-faint and γ-loud young pulsars (red downward triangles), 71 radio-loud and γ-loud millisecond pulsars (green filled circles, circled in black and red when in black-widow and redback systems, respectively), and 2256 other radio pulsars (light blue). Recently discovered millisecond pulsars, with noṖ measurement yet, are plotted as squares atṖ near 10 −21 . Lines of constant spin-down power (brown) and polar magnetic field strength (green) are given for a magnetic dipole i...

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FERMI DISCOVERY OF GAMMA-RAY EMISSION FROM THE GLOBULAR CLUSTER TERZAN 5

Cited by 70 publications

References 25 publications

A population of gamma-ray emitting globular clusters seen with theFermiLarge Area Telescope

A population of gamma-ray emitting globular clusters seen with theFermiLarge Area Telescope

Multi-wavelength environment of the Galactic globular cluster Terzan 5

Gamma-ray pulsars: A gold mine

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