A possible model for the long-term flares of Sgr A{*}

Autor(es)

Okuda, Toru ^[1] ; Singh, Chandra B. ^{[2, 3]} ; Das, Santabrata ^[4] ; Aktar, Ramiz ^[4] ; Nandi, Anuj ^[5] ; de Gouveia Dal Pino, Elisabete M. ^[3]

Afiliação do(s) autor(es)

^[1] Hokkaido Univ, Hakodate Campus, Hachiman Cho 1-2, Hakodate, Hokkaido 0408567 - Japan

^[2] Tel Aviv Univ, Raymond & Beverly Sackler Sch Phys & Astron, IL-69978 Tel Aviv - Israel

^[3] Univ Sao Paulo, Dept Astron IAG USP, BR-05508090 Sao Paulo - Brazil

^[4] Indian Inst Technol Guwahati, Gauhati 781039 - India

^[5] UR Rao Satellite Ctr, Space Astron Grp, SSIF ISITE Campus, Outer Ring Rd, Bangalore 560037, Karnataka - India

• Tipo de documento: Artigo Científico
• Fonte: PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN; v. 71, n. 3 JUN 2019.
• Citações Web of Science: 0

Resumo

We examine the effects of magnetic field on low angular momentum flows with standing shock around black holes in two dimensions. The magnetic field brings change in behavior and location of the shock which results in regularly or chaotically oscillating phenomena of the flow. Adopting fiducial parameters like specific angular momentum, specific energy, and magnetic field strength for the flow around Sgr A{*}, we find that the shock moves back and forth in the range 60-170 R-g, irregularly recurring with a time-scale of similar to 5 d with an accompanying, more rapid, small modulation with a period of 25 hr without fading, where Rg is the Schwarzschild radius. The time-variability associated with the two different periods is attributed to the oscillating outer strong shock, together with another rapidly oscillating inner weak shock. As a consequence of the variable shock location, the luminosities vary roughly by more than a factor of 3. The time-dependent behaviors of the flow are well compatible with luminous flares with a frequency of similar to one per day and bright flares occurring every similar to 5-10 d in the latest observations by Chandra, Swift, and XMM-Newton monitoring of Sgr A{*}. (AU)

• Processo FAPESP: 09/54006-4 - Um cluster de computadores para o Departamento de Astronomia do IAG-USP e para o Núcleo de Astrofísica da UNICSUL
• Beneficiário: Elisabete Maria de Gouveia Dal Pino
• Linha de fomento: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
• Processo FAPESP: 13/10559-5 - Investigação de fenômenos de altas energias e plasmas astrofísicos: teoria, simulações numéricas, observações e desenvolvimento de instrumentação para o Cherenkov Telescope Array (CTA)
• Beneficiário: Elisabete Maria de Gouveia Dal Pino
• Linha de fomento: Auxílio à Pesquisa - Temático
• Processo FAPESP: 13/09065-8 - Origem e colimação de Jatos de Fontes Compactas e Mecanismos de Aceleração
• Beneficiário: Chandra Bahadur Singh
• Linha de fomento: Bolsas no Brasil - Pós-Doutorado