2018ApJ...864L..11X -
Astrophys. J., 864, L11-L11 (2018/September-1)
Flat rotation curves found in merging dusty starbursts at z = 2.3 through tilted-ring modeling.
XUE R., FU H., ISBELL J., IVISON R.J., COORAY A. and OTEO I.
Abstract (from CDS):
The brightest 500 µm source in the XMM-LSS field, HXMM01, is a rare merger of luminous starburst galaxies at z = 2.3 with a dust-obscured star formation rate of 2000 M☉ yr–1. Here we present high-resolution spectroscopic observations of HXMM01 with the Atacama Large Millimeter/submillimeter Array (ALMA). We detect line emission from CO J = 7 - 6, [C I] 3P2 - 3P1, and p-H2O 211 - 202 and continuum emission at 230 GHz. At a spatial resolution of 0.''2 and a spectral resolution of 40 km s–1, the source is resolved into three distinct components, which are spatially and dynamically associated within a projected radius of 20 kpc and a radial velocity range of 2000 km s–1. For two major components, our Bayesian-based tilted-ring modeling of the ALMA spectral cubes shows almost flat rotation curves peaking at ∼500 km s–1 at galactocentric distances between 2 and 5 kpc. Each of them has a dynamical mass of ∼1011 M☉. The combination of the dynamical masses and the archival CO J = 1 - 0 data places strong upper limits on the CO - H2 conversion factor of αCO <= 1.4-2.0 M☉(K km s–1 pc2)–1. These limits are significantly below the Galactic inner disk αCO value of 4.3 M☉(K km s–1 pc2)–1 but are consistent with those of local starbursts. Therefore, the previously estimated short gas depletion timescale of ∼200 Myr remains unchanged.
Abstract Copyright:
© 2018. The American Astronomical Society. All rights reserved.
Journal keyword(s):
galaxies: formation - galaxies: high-redshift - galaxies: individual: HerMES J022016.5-060143 - galaxies: interactions
Simbad objects:
7
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