Universität zu Köln

Subroweit, M., Garcia-Marin, M., Eckart, A., Borkar, A., Valencia-S, M., Witzel, G., Shahzamanian, B. and Straubmeier, C. (2017). Submillimeter and radio variability of Sagittarius A* A statistical analysis. Astron. Astrophys., 601. LES ULIS CEDEX A: EDP SCIENCES S A. ISSN 1432-0746

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Abstract

We report on a statistical analysis of the 345 GHz submillimeter (submm) and 100 GHz radio flux density distribution of Sagittarius A* (Sgr A*). The submm data set consists of 345 GHz data obtained from different Large Apex Bolometer Camera (LABOCA) campaigns between 2008 and 2014, and additional literature data from 2004 to 2009 at comparable wavelengths. The radio observations were carried out with the Australia Telescope Compact Array (ATCA) between 2010 and 2014. We used a combined maximum likelihood estimator (MLE) and Kolmogorov-Smirnov (KS) statistics method to test for a possible power-law distribution in the high flux density excursions (flares) at both wavebands. We find that both flux density distributions can be described by a shifted power-law of the form p(x) alpha (x-s)(-alpha) with alpha similar to 4 (submm: alpha = 4.0 +/- 1.7; radio: alpha = 4.7 +/- 0.8). The same power-law index was previously found for the near-infrared (NIR) flux density distribution. These results may strengthen our preferred flare emission model: a combined synchrotron self-Compton (SSC) and adiabatically expanding self-absorbed synchrotron blob model where the flaring activity across all wavebands stem from the same source components and the variable emission can be described by a single state red noise process. Within the framework of the expanding blob model the similarity of the radio and the submm flux density distribution may also narrow down possible initial synchrotron turnover frequencies nu(0) to be mainly around 350 GHz and possible expansion velocities v exp to be predominantly around 0.01 c.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Subroweit, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Garcia-Marin, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Eckart, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Borkar, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Valencia-S, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Witzel, G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Shahzamanian, B. UNSPECIFIED UNSPECIFIED UNSPECIFIED Straubmeier, C. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-232006
DOI:	10.1051/0004-6361/201628530
Journal or Publication Title:	Astron. Astrophys.
Volume:	601
Date:	2017
Publisher:	EDP SCIENCES S A
Place of Publication:	LES ULIS CEDEX A
ISSN:	1432-0746
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SUPERMASSIVE BLACK-HOLE; X-RAY FLARES; GALACTIC-CENTER; MILKY-WAY; CENTIMETER WAVELENGTHS; INFRARED-EMISSION; FLARING ACTIVITY; TIME-SCALE; SGR; MULTIWAVELENGTH Multiple languages Astronomy & Astrophysics Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/23200