分类： 天文学 >> 天文学 提交时间： 2023-02-19
Nick Scoville
Andreas Faisst
John Weaver
Sune Toft
Henry McCracken
Olivier Ilbert
Tanio Diaz-Santos
Johannes Staguhn
Jin Koda
Caitlin Casey
David Sanders
Bahram Mobasher
Nima Chartab
Zahra Sattari
Peter Capak
Paul Vanden Bout
Angela Bongiorno
Catherine Vlahakis
Kartik Sheth
Min Yun
摘要： ALMA observations of the long wavelength dust continuum are used to estimate the gas masses in a sample of 708 star-forming (SF) galaxies at z = 0.3 to 4.5. We determine the dependence of gas masses and star formation efficiencies (SFE=SFR per unit gass mass). We find that 70 percent of the increase in SFRs of the MS is due to the increased gas masses at earlier epochs while 30 percent is due to increased efficiency of SF. For galaxies above the MS this is reversed with 70 percent of the increased SFR relative to the MS being due to elevated SFEs. Thus, the major evolution of star formation activity at early epochs is driven by increased gas masses, while the starburst activity taking galaxies above the MS is due to enhanced triggering of star formation (likely due to galactic merging). The interstellar gas peaks at z = 2 and dominates the stellar mass down to z = 1.2. Accretion rates needed to maintain continuity of the MS evolution exceed 100 Msun per yr at z > 2. The galactic gas contents are likely the driving determinant for both the rise in SF and AGN activity from z = 5 to their peak at z = 2 and subsequent fall to lower z. We suggest that for self-gravitating clouds with supersonic turbulence, cloud collisions and the filamentary structure of the clouds regulate the star formation activity.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jed McKinney
Luke Finnerty
Caitlin Casey
Maximilien Franco
Arianna Long
Seiji Fujimoto
Jorge Zavala
Olivia Cooper
Hollis Akins
Alexandra Pope
Lee Armus
B. T. Soifer
Kirsten Larson
Keith Matthews
Jason Melbourne
Michael Cushing
摘要： Selecting the first galaxies at z>7-10 from JWST surveys is complicated by z7-10 Lyman Break Galaxies (LBGs). Dust-obscured 3-1.5$ and z>4. While there are some redshifts (z~3.75) where our stack is more degenerate with the photometry of z>10 LBGs between $\lambda_{rest}\sim0.3-0.8\,\mu$m, redder filter coverage beyond $\lambda_{obs}>3.5\,\mu$m and far-IR/sub-mm follow-up may be useful for breaking the degeneracy and making a crucial separation between two fairly unconstrained populations, dust-obscured galaxies at z~3-6 and LBGs at z>10.
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