| Issue |
A&A
Volume 664, August 2022
|
|
|---|---|---|
| Article Number | A97 | |
| Number of page(s) | 15 | |
| Section | Interstellar and circumstellar matter | |
| DOI | https://doi.org/10.1051/0004-6361/202243228 | |
| Published online | 15 August 2022 | |
Regularized 3D spectroscopy with CubeFit: Method and application to the Galactic Center circumnuclear disk★,★★
1
LESIA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CNRS,
5 place Jules Janssen,
92195
Meudon, France
e-mail: thibaut.paumard@observatoiredeparis.psl.eu
2
Department of Physics and Astronomy, University of California Los Angeles,
430 Portola Plaza,
Los Angeles,
CA 90095,
USA
e-mail: ciurlo@astro.ucla.edu
Received:
31
January
2022
Accepted:
20
April
2022
Context. The Galactic Center black hole and the nuclear star cluster are surrounded by a clumpy ring of gas and dust, the circumnuclear disk (CND), that rotates about them at a standoff distance of ≃1.5 pc. The mass and density of individual clumps in the CND are disputed.
Aims. We seek to use H2 to characterize the clump size distribution and to investigate the morphology and dynamics of the interface between the ionized interior layer of the CND and the molecular reservoir lying farther out (corresponding to the inner rim of the CND, illuminated in ultraviolet light by the central star cluster).
Methods. We have observed two fields of approximately 20″ × 20″ in the CND at near-infrared wavelengths with the OSIRIS spectro-imager at the Keck Observatory. These two fields, located at the approaching and receding nodes of the CND, best display this interface. Our data cover two H2 lines as well as the Brγ line (tracing H II). We have developed the tool CubeFit, an original method for extracting maps of continuous physical parameters (such as the velocity field and velocity dispersion) from integral-field spectroscopy data, using regularization to largely preserve spatial resolution in regions of low signal-to-noise ratio.
Results. This original method enables us to isolate compact, bright features in the interstellar medium of the CND. Several clumps in the southwestern field assume the appearance of filaments, many of which are parallel to one another. We conclude that these clumps cannot be self-gravitating.
Key words: methods: data analysis / methods: numerical / techniques: high angular resolution / techniques: spectroscopic / ISM: individual objects: Sgr A West Circumnuclear Disk / Galaxy: center
Figures 4, 5, 8, 9 and B.1 to B.4 are also available in FITS format at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/664/A97
The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.
© T. Paumard et al. 2022
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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