Unraveling emission line galaxy conformity at z~1 with DESI early data

Sihan Yuan; Risa H. Wechsler; Yunchong Wang; Mithi A. C. de los Reyes; Justin Myles; Antoine Rocher; Boryana Hadzhiyska; Jessica Nicole Aguilar; Steven Ahlen; David Brooks; Todd Claybaugh; Shaun Cole; Axel de la Macorra; Jaime E. Forero-Romero; Satya Gontcho A Gontcho; Julien Guy; Klaus Honscheid; Theodore Kisner; Michael Levi; Marc Manera; Aaron Meisner; Ramon Miquel; John Moustakas; Jundan Nie; Nathalie Palanque-Delabrouille; Claire Poppett; Mehdi Rezaie; Ashley J. Ross; Graziano Rossi; Eusebio Sanchez; Michael Schubnel; Hee- Jong Seo; Gregory Tarlé; Benjamin Alan Weaver; Zhimin Zhou

arXiv · 2310.09329

Unraveling emission line galaxy conformity at z~1 with DESI early data

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Abstract

Emission line galaxies (ELGs) are now the preeminent tracers of large-scale structure at z>0.8 due to their high density and strong emission lines, which enable accurate redshift measurements. However, relatively little is known about ELG evolution and the ELG-halo connection, exposing us to potential modeling systematics in cosmology inference using these sources. In this paper, we propose a physical picture of ELGs and improve ELG-halo connection modeling using a variety of observations and simulated galaxy models. We investigate DESI-selected ELGs in COSMOS data, and infer that ELGs are rapidly star-forming galaxies with a large fraction exhibiting disturbed morphology, implying that many of them are likely to be merger-driven starbursts. We further postulate that the tidal interactions from mergers lead to correlated star formation in central-satellite ELG pairs, a phenomenon dubbed "conformity." We argue for the need to include conformity in the ELG-halo connection using galaxy models such as IllustrisTNG, and by combining observations such as the DESI ELG auto-correlation, ELG cross-correlation with Luminous Red Galaxies (LRGs), and ELG-cluster cross-correlation. We also explore the origin of conformity using the UniverseMachine model and elucidate the difference between conformity and the well-known galaxy assembly bias effect.

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Sihan Yuan, Risa H. Wechsler, Yunchong Wang, Mithi A. C. de los Reyes, Justin Myles, Antoine Rocher, Boryana Hadzhiyska, Jessica Nicole Aguilar, Steven Ahlen, David Brooks, Todd Claybaugh, Shaun Cole, Axel de la Macorra, Jaime E. Forero-Romero, Satya Gontcho A Gontcho, Julien Guy, Klaus Honscheid, Theodore Kisner, Michael Levi, Marc Manera, Aaron Meisner, Ramon Miquel, John Moustakas, Jundan Nie, Nathalie Palanque-Delabrouille, Claire Poppett, Mehdi Rezaie, Ashley J. Ross, Graziano Rossi, Eusebio Sanchez, Michael Schubnel, Hee- Jong Seo, Gregory Tarlé, Benjamin Alan Weaver, Zhimin Zhou. 2023-10-13. Unraveling emission line galaxy conformity at z~1 with DESI early data. https://arxiv.org/abs/2310.09329

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