Letter to the Editor

A dual emission mechanism in Sgr A*/L′?

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′ 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′-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′ 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*.