Very-high-energy gamma-ray emission from the direction of the Galactic globular cluster Terzan 5
2011 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 531, L18- p.Article in journal (Refereed) Published
The HESS very-high-energy (VHE, E > 0.1 TeV) gamma-ray telescope system has discovered a new source, HESS J1747-248. The measured integral flux is (1.2 +/- 0.3) x 10(-12) cm(-2) s(-1) above 440 GeV for a power-law photon spectral index of 2.5 +/- 0.3(stat) +/- 0.2(sys). The VHE gamma-ray source is located in the close vicinity of the Galactic globular cluster Terzan 5 and extends beyond the HESS point spread function (0.07 degrees). The probability of a chance coincidence with Terzan 5 and an unrelated VHE source is quite low (similar to 10(-4)). With the largest population of identified millisecond pulsars (msPSRs), a very high core stellar density and the brightest GeV range flux as measured by Fermi-LAT, Terzan 5 stands out among Galactic globular clusters. The properties of the VHE source are briefly discussed in the context of potential emission mechanisms, notably in relation to msPSRs. Interpretation of the available data accommodates several possible origins for this VHE gamma-ray source, although none of them offers a satisfying explanation of its peculiar morphology.
Place, publisher, year, edition, pages
2011. Vol. 531, L18- p.
globular clusters: individual: Terzan 5, radiation mechanisms: non-thermal, pulsars: general, gamma rays: general
IdentifiersURN: urn:nbn:se:su:diva-66601DOI: 10.1051/0004-6361/201117171ISI: 000293017700184OAI: oai:DiVA.org:su-66601DiVA: diva2:468151
authorCount :1962011-12-202011-12-202011-12-20Bibliographically approved