Universität zu Köln

Khabibullin, I., Churazov, E., Sunyaev, R., Federrath, C., Seifried, D. and Walch, S. (2020). X-raying molecular clouds with a short flare: probing statistics of gas density and velocity fields. Mon. Not. Roy. Astron. Soc., 495 (1). S. 1414 - 1433. OXFORD: OXFORD UNIV PRESS. ISSN 1365-2966

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Abstract

We take advantage of a set of molecular cloud simulations to demonstrate a possibility to uncover statistical properties of the gas density and velocity fields using reflected emission of a short (with duration much less than the cloud's light-crossing time) X-ray flare. Such a situation is relevant for the Central Molecular Zone (CMZ) of our Galaxy where several clouds get illuminated by an similar to 110 yr-old flare from the supermassive black hole Sgr A*. Due to shortness of the flare (Delta t less than or similar to 1.6 yr), only a thin slice (Delta z less than or similar to 0.5 pc) of the molecular gas contributes to the X-ray reflection signal at any given moment, and its surface brightness effectively probes the local gas density. This allows reconstructing the density probability distribution function over a broad range of scales with virtually no influence of attenuation, chemo-dynamical biases, and projection effects. Such a measurement is key to understanding the structure and star formation potential of the clouds evolving under extreme conditions in the CMZ. For cloud parameters similar to the currently brightest in X-ray reflection molecular complex Sgr A, the sensitivity level of the best available data is sufficient only for marginal distinction between solenoidal and compressive forcing of turbulence. Future-generationX-ray observatories with large effective area and high spectral resolution will dramatically improve on that by minimizing systematic uncertainties due to contaminating signals. Furthermore, measurement of the iron fluorescent line centroid with sub-eV accuracy in combination with the data on molecular line emission will allow direct investigation of the gas velocity field.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Khabibullin, I. UNSPECIFIED UNSPECIFIED UNSPECIFIED Churazov, E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sunyaev, R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Federrath, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Seifried, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Walch, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-331939
DOI:	10.1093/mnras/staa1262
Journal or Publication Title:	Mon. Not. Roy. Astron. Soc.
Volume:	495
Number:	1
Page Range:	S. 1414 - 1433
Date:	2020
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1365-2966
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language XMM-NEWTON OBSERVATIONS; ACTIVE GALACTIC NUCLEI; STAR-FORMATION; PROBABILITY-DISTRIBUTION; EMISSION LINES; DYNAMICAL EVOLUTION; CENTER REGION; TURBULENCE; ORIGIN; REFLECTION Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/33193