2010/02/03 by P. Eger, W. Domainko, A. -C. Clapson +1
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Brightness #Emission spectrum #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Globular cluster #Population #RADIUS #Spectral line #Stellar population #Surface brightness #astro-ph.HE
paper · pdf · doi:10.1051/0004-6361/200913732
6 pages, 4 figures, accepted for publication by A&A
arxiv created 2010/02/03 · openalex publication_date 2010/02/08 · arxiv updated 2015/05/18 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
<i>Aims. <i/>Terzan 5 , a globular cluster (GC) prominent in mass and population of compact objects, is searched for diffuse X-ray emission, as proposed by several models. <i>Methods. <i/>We analyzed the data of an archival <i>Chandra<i/> observation of Terzan 5 to search for extended diffuse X-ray emission outside the half-mass radius of the GC. We removed detected point sources from the data to extract spectra from diffuse regions around Terzan 5. The Galactic background emission was modeled by a 2-temperature thermal component, which is typical for Galactic diffuse emission. <i>Results. <i/>We detected significant diffuse excess emission above the particle background level from the whole field-of-view. The surface brightness appears to be peaked at the GC center and decreases smoothly outwards. After the subtraction of particle and Galactic background, the excess spectrum of the diffuse emission between the half-mass radius and <i>3'<i/> can be described by a power-law model with photon index <i>Γ<i/> = 0.9 <i>±<i/> 0.5 and a surface flux of <i>F<i/><sub>x<sub/> = (1.17<i>±<i/>0.16) × 10<sup>-7<sup/> erg cm<sup>-2<sup/> s<sup>-1<sup/> sr<sup>-1<sup/> in the 1–7 keV band. We estimated the contribution from unresolved point sources to the observed excess to be negligible. The observations suggest that a purely thermal origin of the emission is less likely than a non-thermal scenario. However, from simple modeling we cannot identify a clearly preferred scenario.