http://arxiv.org/abs/1807.08895
We report Northern Extended Millimeter Array (NOEMA) CO($J = 3 – 2$) observations of the dusty star-forming galaxy ACT-S J0209941+001557 at $z = 2.5528$, which was detected as an unresolved source in the Atacama Cosmology Telescope (ACT) equatorial survey. Our spatially resolved spectral line data support the derivation of a gravitational lens model from 37 independent velocity channel maps using a pixel-based algorithm, from which we infer a velocity-dependent magnification factor $\mu \approx 4-27$ with a luminosity-weighted mean $\left<\mu\right>\approx 14$. The resulting source-plane reconstruction is consistent with a rotating disk, although other scenarios cannot be ruled out by our data. After correction for lensing, we derive a line luminosity $L^{\prime}{\rm CO(3-2)}= (5.06\pm 0.12) \times 10^{10}\,{\rm \,K\,km\,s^{-1}\,pc^{2}}$, a cold gas mass $M{{\rm gas}}= (3.52 \pm 0.21) \times 10^{10}\,M_{\odot}$, a dynamical mass $M_{\rm dyn}\,{\rm sin}^2\,i = 4.0^{+1.7}{-1.3} \times 10^{10}\,M{\odot}$, and a gas mass fraction $f_{\rm gas}\,{\rm csc}^2\,i = 0.9^{+0.5}{-0.3}$. The line brightness temperature ratio of $r{3,1}\approx 1.6$ relative to a Green Bank Telescope CO($J=1-0$) detection may be elevated by a combination of external heating of molecular clouds, differential lensing, and/or pointing errors.
J. Rivera, A. Baker, P. Gallardo, et. al.
Wed, 25 Jul 18
3/60
Comments: 7 pages, 5 figures, submitted to ApJ
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