Milky Way globular clusters in gamma-rays: analysing the dynamical formation of millisecond pulsars

Autor(es)

de Menezes, Raniere ^[1] ; Cafardo, Fabio ^[1] ; Nemmen, Rodrigo ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Dept Astron, BR-05508090 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Monthly Notices of the Royal Astronomical Society; v. 486, n. 1, p. 851-867, JUN 2019.
• Citações Web of Science: 2

Resumo

Globular clusters (GCs) are evolved stellar systems containing entire populations of millisecond pulsars (MSPs), which are efficient gamma-ray emitters. Observations of this emission can be used as a powerful tool to explore the dynamical processes leading to binary system formation in GCs. In this work, 9 yr of Fermi Large-Area Telescope data were used to investigate the gamma-ray emission from all GCs in the Milky Way. Twenty-three clusters were found as gamma-ray bright, with two of them never having been reported before. It was also found that magnetic braking probably has a smaller impact on the formation rate of binary systems in metal-rich GCs than previously suggested, while a large value for the two-body encounter rate seems to be a necessary condition. The influence of the encounter rate per formed binary was for the first time explored in conjunction with gamma-ray data, giving evidence that if this quantity is very high, binary systems will get destroyed before having time to evolve into MSPs, thus decreasing the total number of MSPs in a GC. No extended emission was found even for clusters whose optical extent is approximate to 0.5 degrees; all of them are point-like sources spatially in agreement with the optical cores of the GCs, supporting previous X-ray results of heavier objects sinking into the clusters' cores via dynamical friction. The possibility of extrapolating these results to ultra-compact dwarf galaxies is discussed, as these systems are believed to be the intermediate case between GCs and dwarf galaxies. (AU)

• Processo FAPESP: 17/01461-2 - O universo extremo: buracos negros e o telescópio Fermi
• Beneficiário: Rodrigo Nemmen da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 16/25484-9 - Observações no óptico de candidatos a blazares e fontes de raios gama desconhecidas
• Beneficiário: Raniere Maciel de Menezes
• Modalidade de apoio: Bolsas no Brasil - Doutorado