Detection of Galactic Center source G2 at 3.8 $\mu$m during periapse passage

Abstract

We report new observations of the Galactic Center source G2 from the W. M. Keck Observatory. G2 is a dusty red object associated with gas that shows tidal interactions as it nears closest approach with the Galaxy's central black hole. Our observations, conducted as G2 passed through periapse, were designed to test the proposal that G2 is a 3 earth mass gas cloud. Such a cloud should be tidally disrupted during periapse passage. The data were obtained using the Keck II laser guide star adaptive optics system (LGSAO) and the facility near-infrared camera (NIRC2) through the K' [2.1 $\mu$m] and L' [3.8 $\mu$m] broadband filters. Several results emerge from these observations: 1) G2 has survived its closest approach to the black hole as a compact, unresolved source at L'; 2) G2's L' brightness measurements are consistent with those over the last decade; 3) G2's motion continues to be consistent with a Keplerian model. These results rule out G2 as a pure gas cloud and imply that G2 has a central star. This star has a luminosity of $\sim$30 $L_{\odot }$ and is surrounded by a large ($\sim$2.6 AU) optically thick dust shell. The differences between the L' and Br-$\gamma$ observations can be understood with a model in which L' and Br-$\gamma$ emission arises primarily from internal and external heating, respectively. We suggest that G2 is a binary star merger product and will ultimately appear similar to the B-stars that are tightly clustered around the black hole (the so-called S-star cluster).

Accepted by ApJ Letters, 2014 October 14

References in corpus (5)

• A Constant Spectral Index for Sagittarius A* During Infrared/X-ray Intensity Variations
• The Galactic Center cloud G2 and its gas streamer
• Secular Evolution Of Binaries Near Massive Black Holes: Formation of compact binaries, merger/collision products and G2-like objects
• Photometric Stellar Variability in the Galactic Center
• Dust-enshrouded star near supermassive black hole: predictions for high-eccentricity passages near low-luminosity galactic nuclei

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