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Near-Infrared Flux Limits for Sgr A* Based on NICMOS Data

Stolovy, Susan and Melia, Fulvio and McCarthy, Donald and Yusef-Zadeh, Farhad (2003) Near-Infrared Flux Limits for Sgr A* Based on NICMOS Data. Astronomische Nachrichten, 324 (S1). pp. 419-423. ISSN 0004-6337. doi:10.1002/asna.200385091.

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Images of the central arcsec of the Galaxy at near‐infrared(IR) wavelengths reveal a tight stellar cluster, however, no point source exactly coincident with the radio source Sgr A* has been clearly detected in the near‐IR. “Contaminating” emission due to overlapping point spread functions (PSFs) from this stellar cluster as well as from the bright IRS16 sources 1‐3″ away from Sgr A* makes it difficult to assess directly the near‐IR characteristics of Sgr A*. Taking advantage of the stability of the PSF achieved by HST/NICMOS observations, we employ PSF subtraction techniques in order to investigate the true nature of the near‐IR emission from Sgr A*. New limits on the maximum possible flux emanating from a point source coincident with Sgr A* are presented at 1.1, 1.45, 1.6, 1.9, and 2.2 μm based on NICMOS data taken at several epochs. These are the faintest reported near‐IR flux limits for wavelengths shorter than 2.2 μm. The resulting extinction‐corrected .uxes are compared to theoretical models (including both quiescent and flare models) for the spectrum of Sgr A*. We also present NICMOS narrow‐band emission line images in Paα where signi.cant stellar PSF residuals have been removed to reveal new diffuse structures in the ionized gas near Sgr A* at two epochs.

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Additional Information:© 2003 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim. Issue Online 20 October 2003; Version of Record online: 20 October 2003. We thank Siming Liu for assistance in providing the model curves for Figs. 4 and 5.
Group:Infrared Processing and Analysis Center (IPAC)
Subject Keywords:infrared; stars; Sgr A*; Galactic Center; black hole; interstellar medium
Issue or Number:S1
Record Number:CaltechAUTHORS:20180508-155010435
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Official Citation:Stolovy, S. , Melia, F. , McCarthy, D. and Yusef‐Zadeh, F. (2003), Near‐Infrared Flux Limits for Sgr A* Based on NICMOS Data. Astron. Nachr., 324: 419-423. doi:10.1002/asna.200385091
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86297
Deposited By: Tony Diaz
Deposited On:09 May 2018 14:57
Last Modified:15 Nov 2021 20:37

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