ALMA Observations of the Molecular Gas in the Elliptical Galaxy NGC3557

Abstract

We present the results of CO interferometric observations of the southern elliptical galaxy NGC3557 with ALMA. We have detected both the CO(1-0) emission line and a relatively strong continuum at 3mm. The continuum shows a flat-spectrum central unresolved source (at our angular resolution of 0.7arcsec) and two jets, associated with the larger scale emission observed at lower frequencies. The molecular gas in NGC3557 appears to be concentrated within 250 pc of the center, and shows evidence of organized rotation along the same axis as the stellar component and the symmetry axis of the nuclear dust absorption reported in the literature. We obtained M${}_{H_2}$=(9.0$\pm$2.0)x10${}^7$ M${}_{\odot }$ of molecular gas, which has an average CO(2-1) to CO(1-0) line ratio of 0.7, which is relatively high when compared with the values reported in the literature for bona-fide ellipticals observed with single-dish telescopes. NGC3557 shows further a high excitation peak (i.e., CO(2-1)/CO(1-0) ~ 1.1$\pm$0.3 offset 0.7 arcsec from the center, which appears to be associated with a region of higher velocity dispersion that does not share the overall rotation pattern of the molecular gas, but aligned with the radio jet. The molecular gas disk in this object appears to be stable to local gravitational instabilities.

References in corpus (11)

• The SAURON project -- IX. A kinematic classification for early-type galaxies
• CRATES: An All-Sky Survey of Flat-Spectrum Radio Sources
• Molecular Gas and Star Formation in the SAURON Early-type Galaxies
• The ATLAS3D Project - XXVIII. Dynamically-driven star formation suppression in early-type galaxies
• The dust condensation sequence in red super-giant stars
• Spatially resolved kinematics and stellar populations of brightest cluster and group galaxies
• Southern GEMS Groups I: Dynamical Properties
• The Cool ISM in Elliptical Galaxies. I. A Survey of Molecular Gas
• Jet-ISM Interaction in the Radio Galaxy 3C293: Jet-driven Shocks Heat ISM to Power X-ray and Molecular H2 emission
• Disentangling the Circumnuclear Environs of Centaurus A: III. An Inner Molecular Ring, Nuclear Shocks and the CO to warm H2 interface
• ALMA Observations of Circumnuclear Disks in Early Type Galaxies: 12CO(2-1) and Continuum Properties

Cited by in corpus (4)

• Black Hole Mass Measurements of Radio Galaxies NGC 315 and NGC 4261 Using ALMA CO Observations
• The AGN fuelling/feedback cycle in nearby radio galaxies III. 3D relative orientations of radio jets and CO discs and their interaction
• A 4~Kpc Molecular Gas Lane in Cygnus A
• A Giant Molecular Cloud Catalog in the Molecular Disk of the Elliptical Galaxy NGC 5128 (Centaurus A)