A New Census of the 0.2\textless z \textless3.0 Universe, Part II: The Star-Forming Sequence. Leja, J., Speagle, J. S., Ting, Y., Johnson, B. D., Conroy, C., Whitaker, K. E., Nelson, E. J., van Dokkum, P., & Franx, M. arXiv:2110.04314 [astro-ph], October, 2021. arXiv: 2110.04314
A New Census of the 0.2\textless z \textless3.0 Universe, Part II: The Star-Forming Sequence [link]Paper  abstract   bibtex   
We use the panchromatic SED-fitting code Prospector to measure the galaxy logM\${\textasciicircum}*\$-logSFR relationship (the `star-forming sequence') across \$0.2 {\textless} z {\textless} 3.0\$ using the COSMOS-2015 and 3D-HST UV-IR photometric catalogs. We demonstrate that the chosen method of identifying star-forming galaxies introduces a systematic uncertainty in the inferred normalization and width of the star-forming sequence, peaking for massive galaxies at \${\textbackslash}sim 0.5\$ dex and \${\textbackslash}sim0.2\$ dex respectively. To avoid this systematic, we instead parameterize the density of the full galaxy population in the logM\${\textasciicircum}*\$-logSFR-redshift plane using a flexible neural network known as a normalizing flow. The resulting star-forming sequence has a low-mass slope near unity and a much flatter slope at higher masses, with a normalization \$0.2-0.5\$ dex lower than typical inferences in the literature. We show this difference is due to the sophistication of the Prospector stellar populations modeling: the nonparametric star formation histories naturally produce higher masses while the combination of individualized metallicity, dust, and star formation history constraints produce lower star formation rates than typical UV+IR formulae. We introduce a simple formalism to understand the difference between SFRs inferred from spectral energy distribution fitting and standard template-based approaches such as UV+IR SFRs. Finally, we demonstrate the inferred star-forming sequence is consistent with predictions from theoretical models of galaxy formation, resolving a long-standing \${\textbackslash}sim0.2-0.5\$ dex offset with observations at \$0.5{\textless}z{\textless}3\$. The fully trained normalizing flow including a nonparametric description of \${\textbackslash}rho({\textbackslash}log\{{\textbackslash}rm M\}{\textasciicircum}*,{\textbackslash}log\{{\textbackslash}rm SFR\},z)\$ is made available online to facilitate straightforward comparisons with future work.
@article{leja_new_2021,
	title = {A {New} {Census} of the 0.2{\textless} z {\textless}3.0 {Universe}, {Part} {II}: {The} {Star}-{Forming} {Sequence}},
	shorttitle = {A {New} {Census} of the 0.2{\textless} z {\textless}3.0 {Universe}, {Part} {II}},
	url = {http://arxiv.org/abs/2110.04314},
	abstract = {We use the panchromatic SED-fitting code Prospector to measure the galaxy logM\${\textasciicircum}*\$-logSFR relationship (the `star-forming sequence') across \$0.2 {\textless} z {\textless} 3.0\$ using the COSMOS-2015 and 3D-HST UV-IR photometric catalogs. We demonstrate that the chosen method of identifying star-forming galaxies introduces a systematic uncertainty in the inferred normalization and width of the star-forming sequence, peaking for massive galaxies at \${\textbackslash}sim 0.5\$ dex and \${\textbackslash}sim0.2\$ dex respectively. To avoid this systematic, we instead parameterize the density of the full galaxy population in the logM\${\textasciicircum}*\$-logSFR-redshift plane using a flexible neural network known as a normalizing flow. The resulting star-forming sequence has a low-mass slope near unity and a much flatter slope at higher masses, with a normalization \$0.2-0.5\$ dex lower than typical inferences in the literature. We show this difference is due to the sophistication of the Prospector stellar populations modeling: the nonparametric star formation histories naturally produce higher masses while the combination of individualized metallicity, dust, and star formation history constraints produce lower star formation rates than typical UV+IR formulae. We introduce a simple formalism to understand the difference between SFRs inferred from spectral energy distribution fitting and standard template-based approaches such as UV+IR SFRs. Finally, we demonstrate the inferred star-forming sequence is consistent with predictions from theoretical models of galaxy formation, resolving a long-standing \${\textbackslash}sim0.2-0.5\$ dex offset with observations at \$0.5{\textless}z{\textless}3\$. The fully trained normalizing flow including a nonparametric description of \${\textbackslash}rho({\textbackslash}log\{{\textbackslash}rm M\}{\textasciicircum}*,{\textbackslash}log\{{\textbackslash}rm SFR\},z)\$ is made available online to facilitate straightforward comparisons with future work.},
	urldate = {2021-10-25},
	journal = {arXiv:2110.04314 [astro-ph]},
	author = {Leja, Joel and Speagle, Joshua S. and Ting, Yuan-Sen and Johnson, Benjamin D. and Conroy, Charlie and Whitaker, Katherine E. and Nelson, Erica J. and van Dokkum, Pieter and Franx, Marijn},
	month = oct,
	year = {2021},
	note = {arXiv: 2110.04314},
	keywords = {Astrophysics - Astrophysics of Galaxies},
}

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