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Cited by 228Astrophysics and Star Formation StudiesAstrophysical Phenomena and ObservationsGalaxies: Formation, Evolution, Phenomena

HCN and HCO+Observations of the Galactic Circumnuclear Disk

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Christopher, M. H., Scoville, N. Z., Stolovy, S. R., Yun, Min S.·2005·The Astrophysical Journal
DOI 10.1086/427911
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Abstract

We present high spatial resolution (5 1 × 2 7) Owens Valley Radio Observatory (OVRO) millimeter array observations of HCN ( J = 1-0) and HCO + ( J = 1-0) emission in the inner 3 pc of the Galaxy (0.04 pc ~ 1''). The HCN and HCO + emission of the circumnuclear disk (CND) is distributed in a well-defined ring with a peak at a radius of 1.6 pc. The observed radial velocities are generally consistent with rotation at ~110 km s -1 (except along the western edge of the CND). The HCO + /HCN emission ratio is typically ~0.4 but with significant variations. The variations in the HCO + /HCN emission and absorption ratios can be attributed to greater abundances of HCO + in lower density regions both within the CND and along the line of sight. The HCN emission is well correlated with the H 2 emission at 2.12 μm both in the main emission lobes of the CND and also in four H 2 and HCN filaments. Multiple areas of interaction between the ionized gas and the CND are also seen; the western arm of the minispiral is spatially and kinematically consistent with being the ionized inner edge of the CND, and the northern arm may be connected to the CND northeastern extension. With the enhanced spatial resolution of the HCN maps, we resolve numerous dense molecular gas cores within the CND with characteristic diameter ~7'' (0.25 pc). For 26 of the more isolated cores, we have measured sizes, velocity widths, and integrated fluxes. From these properties we estimated three masses for each core: a virial mass assuming the cores are gravitationally bound, an optically thick mass from observed column densities of HCN, and a lower limit mass assuming the HCN emission is optically thin and shock excitation is negligible. The virial and optically thick masses are in good agreement with a typical mass of (2-3) × 10 4 M ☉ and a total CND gas mass of 10 6 M ☉ . The internal densities implied by these core masses (assuming a uniform density distribution for each core) are on average (3-4) × 10 7 cm -3 . The core densities are high enough to be stable against tidal disruption from Sgr A* and the central stellar concentration. This tidal stability suggests a longer lifetime for the CND. The high densities and masses within the cores might support star formation either in the CND itself or within a core infalling toward the inner parsec, thus providing a mechanism for the formation of the young stellar population observed in the inner arcseconds of the Galaxy.

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  • Most of the CND clumps are compact enough to overcome the tidal force from Sgr A* and may either remain in rough equilibrium or form stars.

    “Most of these clumps are compact enough to overcome the tidal force from Sgr A ∗ and may either remain in rough equilibrium or form stars. (Shukla et al. 2004; Christopher et al. 2005; Hsieh et al. 2021).”

    From The Fermi/eROSITA bubbles: a look into the nuclear outflow from the Milky Way (2024) · cites this paper as Christopher et al. 2005

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1 of the 65 references couldn’t be matched to a known paper.

Research works printed but not linked: 4

  1. Genzel, R. 2001, in ASP Conf. Ser. 228, Dynamics of Star Clusters and the Milky Way (San Francisco: ASP), 291
  2. Kaifu, N., Hayashi, M., Inatani, I., & Gatley, I. 1987, in AIP Conf. Proc. 155, The Galactic Center ( New York: AIP), 106
  3. Sault, R. J., Teuben, P. J., & Wright, M. C. H. 1995, in ASP Conf. Ser. 77, Astronomical Data Analysis Software and Systems IV, Vol. 4 (San Francisco: ASP), 433
  4. Stolovy, S. R. 1997, Ph.D. thesis, Cornell Univ.

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Authors
Christopher, M. H., Scoville, N. Z., Stolovy, S. R., & Yun, M. S.
Affiliations
  • California Institute of Technology (US)
  • University of Massachusetts Amherst (US)
ORCID
Venue
The Astrophysical Journal
Publisher
American Astronomical Society
Published
2005-03-20
Volume
622
Issue
1
Pages
346-365
ISSN
  • 0004-637X (ISSN-L)
  • 1538-4357
DOI
10.1086/427911
OpenAlex
W2016787644
Cited by
228
References
65
Citations by year
2026: 8 · 2025: 6 · 2024: 3 · 2023: 4 · 2022: 7 · 2021: 10 · 2020: 2 · 2019: 6 · 2018: 10 · 2017: 13 · 2016: 21 · 2015: 19 · 2014: 12 · 2013: 23 · 2012: 16
FWCI
7.37
Type
journal article
Language
en
Open access
Locations
  • The Astrophysical Journal (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • ScholarWorks@UMassAmherst (University of Massachusetts Amherst) (submittedVersion)
  • CERN Document Server (European Organization for Nuclear Research) (submittedVersion)
  • Scholarworks (University of Massachusetts Amherst) (submittedVersion)
  • arXiv (Cornell University)
Funders
National Science Foundation (0228955, 9981546)
Topics
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astrophysics and Star Formation Studies
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Astrophysical Phenomena and Observations
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Galaxies: Formation, Evolution, Phenomena
Keywords
hydrogen cyanide, HCO+, circumnuclear disk, Galactic Center, virial mass, core density, Sgr A*, H2 emission, molecular ring, molecular gas mass, galactic rotation velocity, shock excitation

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