Accueil > Séminaires d’Astrophysique > Sagittarius A* : Variable and Polarized Emission traces the Accretion onto a Massive Black Hole at the Center of the Milky Way

 

Sagittarius A* : Variable and Polarized Emission traces the Accretion onto a Massive Black Hole at the Center of the Milky Way

Andreas Eckart (Physikalisches Institut, Université de Cologne)

Par Stephane Charpinet - 3/04/2007

 

Séminaires d’Astrophysique

de l’Observatoire Midi-Pyrénées


Séminaire de

Andreas ECKART

 (Physikalisches Institut, Université de Cologne)


Jeudi 5 Avril 2007 à 11h

LATT - Salle Coriolis


Sagittarius A* : Variable and Polarized Emission traces the Accretion onto a Massive Black Hole at the Center of the Milky Way

The compact source SgrA* that can be associated with the massive black hole at the center of the Milky Way shown a strong variability from the radio to the X-ray wavelength domain. Here report on the latest simultaneous NIR/sub-millimeter/X-ray observations using the NACO adaptive optics (AO) instrument at the European Southern Observatory’s Very Large Telescope. In the X-ray and radio domain we used the ACIS-I instrument aboard the Chandra X-ray Observatory and the Submillimeter Array on Mauna Kea, Hawaii, as well as the Very Large Array in New Mexico, respectively. We also summarize the most recent results from a VLT NACO observations of polarized NIR flare emission of SgrA*. We interpret the results using a model in which spots are on relativistic orbits around SgrA* and discuss the possibility of a jet or outflow from such a disk. We find that the variable NIR emission of SgrA* is highly polarized and consists of a contribution of a non- or weakly polarized main flare with highly polarized sub-flares. The flare activity shows a possible quasi-periodicity of 18±3 min consistent with previous observations. The highly variable and polarized emission supports that the NIR emission is non-thermal and is in agreement with emission from a a jet or temporary disk. Alternative explanations for the high central mass concentration involving boson or fermion balls are increasingly unlikely.

 

 

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Laboratoire Astrophysique de Toulouse - Tarbes (UMR5572)

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Univ. Paul Sabatier

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