The Impact of Galaxy-halo Size Relations on Galaxy Clustering Signals

Galaxies come in different sizes and morphologies, and these differences are thought to correlate with properties of their underlying dark matter halos. However, identifying the specific halo property that controls the galaxy size is a challenging task, especially because most halo properties depend...

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Main Authors: Joshua B. Hill, Yao-Yuan Mao
Format: Article
Language:English
Published: Maynooth Academic Publishing 2025-05-01
Series:The Open Journal of Astrophysics
Online Access:https://doi.org/10.33232/001c.137527
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author Joshua B. Hill
Yao-Yuan Mao
author_facet Joshua B. Hill
Yao-Yuan Mao
author_sort Joshua B. Hill
collection DOAJ
description Galaxies come in different sizes and morphologies, and these differences are thought to correlate with properties of their underlying dark matter halos. However, identifying the specific halo property that controls the galaxy size is a challenging task, especially because most halo properties depend on one another. In this work, we demonstrate this challenge by studying how the galaxy-halo size relations impact the galaxy clustering signals. We investigate the reason that a simple linear relation model, which prescribes that the galaxy size is linearly proportional to the dark matter halo's virial radius, can still produce clustering signals that match the observational data reasonably well. We find that this simple linear relation model for galaxy sizes, when combined with the subhalo abundance matching technique, introduces an implicit dependence on the halo formation history. As a result, the effect of halo assembly bias enters the resulting galaxy clustering, especially at lower stellar masses, producing a clustering signal that resembles the observed one. At higher stellar masses, the effect of halo assembly bias weakens and is partially canceled out by the effect of halo bias, and the clustering of large and small galaxies becomes more similar. This combined effect implies that small and large galaxies not only occupy halos of different masses, but they must also occupy halos of different assembly histories. Our study highlights the challenge of identifying a particular halo property that controls galaxy sizes through constraints from galaxy clustering alone.
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spelling doaj-art-aca77d7aa63d4d2a9fce89225f77840b2025-08-20T03:33:43ZengMaynooth Academic PublishingThe Open Journal of Astrophysics2565-61202025-05-01810.33232/001c.137527The Impact of Galaxy-halo Size Relations on Galaxy Clustering SignalsJoshua B. HillYao-Yuan MaoGalaxies come in different sizes and morphologies, and these differences are thought to correlate with properties of their underlying dark matter halos. However, identifying the specific halo property that controls the galaxy size is a challenging task, especially because most halo properties depend on one another. In this work, we demonstrate this challenge by studying how the galaxy-halo size relations impact the galaxy clustering signals. We investigate the reason that a simple linear relation model, which prescribes that the galaxy size is linearly proportional to the dark matter halo's virial radius, can still produce clustering signals that match the observational data reasonably well. We find that this simple linear relation model for galaxy sizes, when combined with the subhalo abundance matching technique, introduces an implicit dependence on the halo formation history. As a result, the effect of halo assembly bias enters the resulting galaxy clustering, especially at lower stellar masses, producing a clustering signal that resembles the observed one. At higher stellar masses, the effect of halo assembly bias weakens and is partially canceled out by the effect of halo bias, and the clustering of large and small galaxies becomes more similar. This combined effect implies that small and large galaxies not only occupy halos of different masses, but they must also occupy halos of different assembly histories. Our study highlights the challenge of identifying a particular halo property that controls galaxy sizes through constraints from galaxy clustering alone.https://doi.org/10.33232/001c.137527
spellingShingle Joshua B. Hill
Yao-Yuan Mao
The Impact of Galaxy-halo Size Relations on Galaxy Clustering Signals
The Open Journal of Astrophysics
title The Impact of Galaxy-halo Size Relations on Galaxy Clustering Signals
title_full The Impact of Galaxy-halo Size Relations on Galaxy Clustering Signals
title_fullStr The Impact of Galaxy-halo Size Relations on Galaxy Clustering Signals
title_full_unstemmed The Impact of Galaxy-halo Size Relations on Galaxy Clustering Signals
title_short The Impact of Galaxy-halo Size Relations on Galaxy Clustering Signals
title_sort impact of galaxy halo size relations on galaxy clustering signals
url https://doi.org/10.33232/001c.137527
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