Clues to the origin of Fermi bubbles from O VIII/O VII LINE RATIO

Sarkar, Kartick C and Nath, Biman B and Sharma, Prateek (2017) Clues to the origin of Fermi bubbles from O VIII/O VII LINE RATIO. In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 467 (3). pp. 3544-3555.

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Abstract

We constrain the origin of Fermi bubbles using 2D hydrodynamical simulations of both star formation-driven and black hole accretion-driven wind models. We compare our results with recent observations of O VIII to OVII line ratio within and near Fermi bubbles. Our results suggest that independent of the driving mechanisms, a low-luminosity (L similar to 0.7-1 x 10(41) erg s(-1)) energy injection best reproduces the observed line ratio for which the shock temperature is approximate to 3 x 10(6) K. Assuming the Galactic halo temperature to be 2 x 10(6) K, we estimate the shock velocity to be similar to 300 km s(-1) for a weak shock. The corresponding estimated age of the Fermi bubbles is similar to 15-25 Myr. Such an event can be produced either by a star formation rate of similar to 0.5 M-circle dot yr(-1) at the Galactic Centre or a very low-luminosity jet/accretion wind arising from the central black hole. Our analysis rules out any activity that generates an average mechanical luminosity greater than or similar to 1041 erg s(-1) as a possible origin of the Fermi bubbles.

Item Type:	Journal Article
Publication:	MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
Additional Information:	Copy right for this article belongs to the OXFORD UNIV PRESS, GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND
Department/Centre:	Division of Physical & Mathematical Sciences > Joint Astronomy Programme Division of Physical & Mathematical Sciences > Physics
Date Deposited:	20 May 2017 04:10
Last Modified:	20 May 2017 04:10
URI:	http://eprints.iisc.ac.in/id/eprint/56835

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