Unraveling emission line galaxy conformity at <i>z</i> ∼ 1 with DESI early data

ABSTRACT Emission line galaxies (ELGs) are now the preeminent tracers of large-scale structure at $z &amp;gt; 0.8$ 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 modelling systematics in cosmology inference using these sources. In this paper, we use a variety of observations and simulated galaxy models to propose a physical picture of ELGs and improve ELG–halo connection modelling in a halo occupation distribution framework. We investigate Dark Energy Spectroscopic Instrument (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 autocorrelation, ELG cross-correlation with luminous red galaxies, 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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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2025-02-27
DOI
https://doi.org/10.1093/mnras/staf368
Citations
11
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
12.70

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article

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

J. Myles, D. Brooks, Yunchong Wang, N. Palanque‐Delabrouille et al.
11 citations
Monthly Notices of the Royal Astronomical Society
Galaxies: Formation, Evolution, Phenomena
12.70
article

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

J. Myles, D. Brooks, Yunchong Wang, N. Palanque‐Delabrouille, Gregory Tarlé, Mithi A. C. de los Reyes, Axel de la Macorra, Jundan Nie, Shaun Cole, M. E. Levi, Marc Manera, Sihan Yuan, J. Aguilar, Eusebio Sanchez, Satya Gontcho A Gontcho, A. Rocher, J. E. Forero-Romero, Steven P. Ahlen, Aaron Meisner, Theodore S. Kisner, Mehdi Rezaie, Risa H. Wechsler, John Moustakas, Zhimin Zhou, Hee‐Jong Seo, Claire Poppett, T. Claybaugh, Graziano Rossi, Boryana Hadzhiyska, Julien Guy, Benjamin A. Weaver, Ramon Miquel, Klaus Honscheid, Michael Schubnell, Ashley J Ross
article en
11 citations

Abstract

ABSTRACT Emission line galaxies (ELGs) are now the preeminent tracers of large-scale structure at $z &amp;gt; 0.8$ 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 modelling systematics in cosmology inference using these sources. In this paper, we use a variety of observations and simulated galaxy models to propose a physical picture of ELGs and improve ELG–halo connection modelling in a halo occupation distribution framework. We investigate Dark Energy Spectroscopic Instrument (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 autocorrelation, ELG cross-correlation with luminous red galaxies, 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.

Monthly Notices of the Royal Astronomical SocietyVol. 538(2)
Boston University (US), Institució Catalana de Recerca i Estudis Avançats (ES), Lawrence Berkeley National Laboratory (US), Universidad de Los Andes (CO), Amherst College (US), Institute for High Energy Physics (ES), Kansas State University (US), Durham University (GB), Chinese Academy of Sciences (CN), Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR), Université Paris-Saclay (FR), University of Michigan (US), Miller College (US), SLAC National Accelerator Laboratory (US), Sejong University (KR), Kavli Institute for Particle Astrophysics and Cosmology (US), Ohio University (US), Université Bourgogne Franche-Comté (FR), CEA Paris-Saclay (FR), Community Science and Data Center (US), NSF NOIRLab (US), National Astronomical Observatories (CN), Institut de Recherche sur les Lois Fondamentales de l'Univers (FR), Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (ES), Institute of Science and Technology, University College London (GB), The Ohio State University (US), Universidad Nacional Autónoma de México (MX), Siena College (US), University of California, Berkeley (US), Stanford University (US)
National Science Foundation, U.S. Department of Energy, Stanford University, Consejo Nacional de Ciencia y Tecnología, SLAC National Accelerator Laboratory
Openalex Percentile: Top 1%
Galaxies: Formation, Evolution, Phenomena
12.70
DOIOpen Access PDFOpenAlex
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