Garcia-Marin, M., Eckart, A., Weiss, A., Witzel, G., Bremer, M., Zamaninasab, M., Morris, M. R., Schoedel, R., Kunneriath, D., Nishiyama, S. ORCID: 0000-0002-9440-7172, Baganoff, F., Dovciak, M., Sabha, N., Duschl, W. J., Moultaka, J., Karas, V., Najarro, F., Muzic, K., Straubmeier, C., Vogel, S. N., Krips, M. and Wiesemeyer, H. (2011). EXTENDED SUBMILLIMETER EMISSION OF THE GALACTIC CENTER AND NEAR-INFRARED/SUBMILLIMETER VARIABILITY OF ITS SUPERMASSIVE BLACK HOLE. Astrophys. J., 738 (2). BRISTOL: IOP PUBLISHING LTD. ISSN 1538-4357

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Abstract

The innermost tens of parsecs of our Galaxy are characterized by the presence of molecular cloud complexes surrounding Sgr A*, the radiative counterpart of the supermassive black hole (similar to 4 x 10(6)M(circle dot)) at the Galactic center. We seek to distinguish the different physical mechanisms that dominate the molecular clouds at the Galactic center, with special emphasis on the circumnuclear disk (CND). We also want to study the energy flow and model the variable emission of Sgr A*. Our study is based on NIR and submillimeter (sub-mm) observations. Using sub-mm maps, we describe the complex morphology of the molecular clouds and the circumnuclear disk, along with their masses (of order 10(5)-10(6)M(circle dot)), and derive also the temperature and spectral index maps of the regions under study. We conclude that the average temperature of the dust is 14 +/- 4 K. The spectral index map shows that the 20 and 50 km s(-1) clouds are dominated by dust emission. Comparatively, in the CND and its surroundings the spectral indices decrease toward Sgr A* and range between about 1 and -0.6. These values are mostly explained with a combination of dust, synchrotron, and free-free emission in different ratios. The presence of non-thermal emission also accounts for the apparent low temperatures derived in these areas, indicating their unreliability. The Sgr A* light curves show significant flux density excursions in both the NIR and sub-mm domains. We have defined a classification system to account for the NIR variability of Sgr A*. Also, we have modeled on the NIR/sub-mm events. From our modeling results we can infer a sub-mm emission delay with respect to the NIR; we argue that the delay is due to the adiabatic expansion of the synchrotron source components.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Garcia-Marin, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Eckart, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Weiss, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Witzel, G.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Bremer, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Zamaninasab, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Morris, M. R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Schoedel, R.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Kunneriath, D.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Nishiyama, S.UNSPECIFIEDorcid.org/0000-0002-9440-7172UNSPECIFIED
Baganoff, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Dovciak, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Sabha, N.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Duschl, W. J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Moultaka, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Karas, V.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Najarro, F.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Muzic, K.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Straubmeier, C.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Vogel, S. N.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Krips, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Wiesemeyer, H.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-489116
DOI: 10.1088/0004-637X/738/2/158
Journal or Publication Title: Astrophys. J.
Volume: 738
Number: 2
Date: 2011
Publisher: IOP PUBLISHING LTD
Place of Publication: BRISTOL
ISSN: 1538-4357
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
SGR-A-ASTERISK; STELLAR PROPER MOTIONS; HOT MOLECULAR GAS; X-RAY; INFRARED FLARES; CONTINUUM OBSERVATIONS; MAGNETIC-FIELD; CENTER REGION; SAGITTARIUS; RADIOMultiple languages
Astronomy & AstrophysicsMultiple languages
URI: http://kups.ub.uni-koeln.de/id/eprint/48911

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