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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

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

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Okuda, Toru [1] ; Singh, Chandra B. [2, 3] ; Das, Santabrata [4] ; Aktar, Ramiz [4] ; Nandi, Anuj [5] ; de Gouveia Dal Pino, Elisabete M. [3]
Total Authors: 6
[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
Total Affiliations: 5
Document type: Journal article
Web of Science Citations: 0

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)

FAPESP's process: 09/54006-4 - A computer cluster for the Astronomy Department of the University of São Paulo Institute of Astronomy, Geophysics and Atmospheric Sciences and for the Cruzeiro do Sul University Astrophysics Center
Grantee:Elisabete Maria de Gouveia Dal Pino
Support type: Multi-user Equipment Program
FAPESP's process: 13/10559-5 - Investigation of high energy and plasma astrophysics phenomena: theory, numerical simulations, observations, and instrument development for the Cherenkov Telescope Array (CTA)
Grantee:Elisabete Maria de Gouveia Dal Pino
Support type: Research Projects - Thematic Grants
FAPESP's process: 13/09065-8 - Origin and collimation of compact source jets and acceleration mechanisms
Grantee:Chandra Bahadur Singh
Support type: Scholarships in Brazil - Post-Doctorate