J/A+A/601/A80 LABOCA 345GHz observations of Sgr A* (Subroweit+, 2017)
Submillimeter and radio variability of Sagittarius A*. A statistical analysis.
Subroweit M., Garcia-Marin M., Eckart A., Borkar A., Valencia-S. M.,
Witzel G., Shahzamanian B., Straubmeier C.
<Astron. Astrophys. 601, A80 (2017)>
=2017A&A...601A..80S 2017A&A...601A..80S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Radio sources ; Millimetric/submm sources
Keywords: black hole physics - galaxies: statistics - Galaxy: nucleus -
Galaxy: nucleus - radio continuum: general - submillimeter: general -
Galaxy: center
Abstract:
We report on a statistical analysis of the 345GHz submillimeter
(submm) and 100GHz radio flux density distribution of Sagittarius A*
(Sgr A*). The submm data set consists of 345GHz 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)∝(x-S)-α with α∼4 (submm: α=4.0±1.7,
radio: α=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 ν0 to be mainly around 350GHz and
possible expansion velocities vexp to be predominantly around 0.01c.
Description:
LABOCA is a multi-channel bolometer array, consisting of 295 channels,
installed at the APEX telescope. APEX is a 12m radio telescope
located at the Llano de Chajnantor Observatory 50km east of San Pedro
de Atacama in northern Chile. It is situated at an altitude of 5014m.
LABOCA operates in the 345GHz (870um) atmospheric window and has a
bandwidth of 60GHz. The beam shape can be described as a circular
Gaussian with a full width half maximum (FWHM)∼19".
Photometry data of the submm APEX/LABOCA observations from 2008 to
2014.
Objects:
----------------------------------------------------
RA (2000) DE Designation(s)
----------------------------------------------------
17 45 40.04 -29 00 28.2 Sgr A* = NAME Sgr A*
----------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
photom.dat 41 792 APEX/LABOCA observations of the Galactic Center
--------------------------------------------------------------------------------
See also:
J/A+A/534/A117 : NIR polarimetry of sources near SgrA* (Buchholz+, 2011)
J/MNRAS/428/2731 : SgrA* emission at 7mm (Beaklini+, 2013)
J/ApJ/820/90 : 4yr 1.3mm VLBI observations of SgrA* with EHT (Fish+, 2016)
Byte-by-byte Description of file: photom.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 20 F20.14 d MJD Time of observation
22- 41 F20.18 Jy Flux LABOCA 345GHz flux density
--------------------------------------------------------------------------------
Acknowledgements:
Matthias Subroweit, subroweit(at)ph1.uni-koeln.de
(End) Patricia Vannier [CDS] 24-Apr-2017