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Issue A&A
Volume 439, Number 2, August IV 2005
Page(s) L9 - L13
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200500146



A&A 439, L9-L13 (2005)
DOI: 10.1051/0004-6361:200500146

Letter

A dual emission mechanism in Sgr A*/L$^\prime$ ?

Y. Clénet1, D. Rouan1, D. Gratadour1, O. Marco2, P. Léna1, N. Ageorges2 and E. Gendron1

1  Observatoire de Paris, LESIA, 5 place Jules Janssen, 92195 Meudon Cedex, France
    e-mail: [yann.clenet;daniel.rouan;damien.gratadour;pierre.lena;eric.gendron]@obspm.fr
2  European Southern Observatory (ESO), Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19, Chile
    e-mail: [nageorges;omarco]@eso.org

(Received 28 April 2005 / Accepted 26 June 2005)

Abstract
We have collected in 2004 adaptive optics corrected $L^\prime$ images of the Galactic Center region with NAOS-CONICA at VLT. A strong variability was observed as well as a correlation between the photocenter positions and fluxes of the $L^\prime$-band counterpart of Sgr A* . It is interpreted as the combined emission of a point-like flaring source at the position of Sgr A*/IR itself and an extended dust structure, 75 mas south west of Sgr A*/IR , which we name Sgr A*-f . We examine the different possible mechanisms to explain this dual Sgr A* $L^\prime$ emission and conclude it is likely a flaring emission associated to energetic events in the close environment of the black hole plus a quiescent emission resulting from the collision of Sgr A*-f by a jet from Sgr A* .


Key words: Galaxy: center -- infrared: stars -- instrumentation: adaptive optics

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© ESO 2005


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