2012ApJ...757..157P -
Astrophys. J., 757, 157 (2012/October-1)
Molecular and atomic line surveys of galaxies. II. Unbiased estimates of their star formation mode.
PAPADOPOULOS P.P. and GEACH J.E.
Abstract (from CDS):
We make use of our "minimal" cold interstellar medium emission line model that predicts the molecular and atomic line emission per unit dense, star-forming gas mass to examine the utility of key line ratios in surveys of the so-called star formation "mode" as traced by ξSF= Mdense(H2)/M total(H2). We argue that ξSF and its proxies provide very sensitive, extinction-free discriminators of rapid starburst/merger-driven versus secular quiescent/disk-like stellar mass assembly, with the most promising diagnostic to be applied in the near-future being CO J(4 ⟶ 3)/ [C I](3 P1 ⟶ 3 P0). These lines are accessible across nearly the full range 0 < z < 2 (thus covering the bulk of galaxy evolution) with the Atacama Large Millimeter Array. In addition to their diagnostic power, another advantage of this combination is the similar observed frequencies (Δν0~ 30 GHz) of the lines, resulting in nearly spatially matched beams for a fixed aperture, thus mitigating the effects of resolution/morphology bias in the interpretation of galaxy-averaged line ratios. Finally, we discuss the capability of deep blind redshift surveys with the high-frequency component of the Square Kilometer Array (SKA) in discovering H2-rich galaxies with very low ξSF values. These could be the progenitors of starburst galaxies seen prior to the onset of star formation; such galaxies could be a class of extreme outliers from local (gas surface density)-(star formation rate) scaling laws, which would exclude them from current star formation or stellar-mass-selected samples. Our conservative model suggests that SKA could detect such systems residing at z ∼ 3 at a rate of 20-200/hr.
Abstract Copyright:
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Journal keyword(s):
cosmology: observations - galaxies: ISM - galaxies: evolution - galaxies: starburst - ISM: atoms - ISM: molecules
Simbad objects:
11
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