2017ApJ...851L..40B -
Astrophys. J., 851, L40-L40 (2017/December-3)
Spatially resolved kinematics in the central 1 kpc of a compact star-forming galaxy at z ∼ 2.3 from ALMA CO observations.
BARRO G., KRIEK M., PEREZ-GONZALEZ P.G., DIAZ-SANTOS T., PRICE S.H., RUJOPAKARN W., PANDYA V., KOO D.C., FABER S.M., DEKEL A., PRIMACK J.R. and KOCEVSKI D.D.
Abstract (from CDS):
We present high spatial resolution (FWHM ∼ 0.''14) observations of the CO(8-7) line in GDS-14876, a compact star-forming galaxy at z = 2.3 with a total stellar mass of log(M*/M☉) = 10.9. The spatially resolved velocity map of the inner r <= 1 kpc reveals a continuous velocity gradient consistent with the kinematics of a rotating disk with vrot(r = 1 kpc) = 163 ± 5 km s–1 and vrot/σ ∼ 2.5. The gas-to-stellar ratios estimated from CO(8-7) and the dust continuum emission span a broad range, fgasCO=Mgas/M*=13 % –45 % and fgascont=50 % –67 % , but are nonetheless consistent given the uncertainties in the conversion factors. The dynamical modeling yields a dynamical mass of log(Mdyn/M☉)=10.58–0.2+0.5, which is lower, but still consistent with the baryonic mass, log(Mbar=M*+MgasCO/M☉)=11.0, if the smallest CO-based gas fraction is assumed. Despite a low, overall gas fraction, the small physical extent of the dense, star-forming gas probed by CO(8-7), ∼3x smaller than the stellar size, implies a strong relative concentration that increases the gas fraction up to fgasCO,1 kpc∼85 % in the central 1 kpc. Such a gas-rich center, coupled with a high star formation rate (SFR) ∼ 500 M☉ yr–1, suggests that GDS-14876 is quickly assembling a dense stellar component (bulge) in a strong nuclear starburst. Assuming its gas reservoir is depleted without replenishment, GDS-14876 will quickly (tdepl ∼ 27 Myr) become a compact quiescent galaxy that could retain some fraction of the observed rotational support.
Abstract Copyright:
© 2017. The American Astronomical Society. All rights reserved.
Journal keyword(s):
galaxies: high-redshift - galaxies: photometry - galaxies: photometry
CDS comments:
The galaxy GDS-14876 was not created in SIMBAD for lack of coordinates.
Simbad objects:
1
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