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arXiv · 2412.03662

The Growth of Galaxy Stellar Haloes Over $0.2 \leq z \leq 1.1$

Devin J. Williams·Ivana Damjanov·Marcin Sawicki·Harrison Souchereau·Lingjian Chen·Guillaume Desprez·Angelo George·Marianna Annunziatella·Stéphane Arnouts·Stephen Gwyn·Danilo Marchesini·Anna Sajina
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Abstract

Galaxies are predicted to assemble their stellar haloes through the accretion of stellar material from interactions with their cosmic environment. Observations that trace stellar halo buildup probe the processes that drive galaxy size and stellar mass growth. We investigate stellar halo assembly over $0.2 \leq z \leq 1.1$ in a mass-complete ($M_{\star} \geq 10^{9.5}M_{\odot}$) sample of 242,456 star-forming and 88,421 quiescent galaxies (SFGs and QGs) from the CLAUDS and HSC-SSP surveys. We extract galaxy rest-frame $g$-band surface brightness ($μ_g$) profiles to study faint, extended emission in galaxy outskirts. We examine trends in galaxy assembly by analyzing the median $μ_g$ profiles in different SFG and QG \msS ranges with decreasing redshift and connecting evolution in galaxy $μ_g$ profiles with the underlying stellar mass growth in galaxies. Since $z=1.1$, the majority of evolution in the median $μ_g$ profiles of galaxies ($\sim$64$\%$ in SFGs and $\sim$71$\%$ in QGs) occurs throughout their stellar halo regions (2-10$R_e$). More massive galaxies assemble stellar halo material more rapidly at $0.2 \leq z \leq 1.1$. Over this period, QGs grow a larger fraction of their stellar haloes than SFGs at fixed $M_{\star}$ (factor of $\sim$1.2). Although star formation can account for the stellar halo growth observed in low-mass SFGs ($10^{9.5}M_\odot \leq M_\star < 10^{10.5}M_\odot$), high-mass SFGs ($M_\star \geq 10^{10.5}M_\odot$) and both low- and high-mass QGs require an additional assembly mechanism. Our results suggest accretion via minor mergers drives additional stellar halo growth in these galaxies. The contribution from accretion is larger in more massive galaxies (over $M_{\star} \geq 10^{9.5}M_{\odot}$), and QGs exhibit larger fractional increases to their ex-situ fractions over $0.2 \leq z \leq 1.1$ than SFGs at fixed $M_{\star}$.

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Devin J. Williams, Ivana Damjanov, Marcin Sawicki, Harrison Souchereau, Lingjian Chen, Guillaume Desprez, Angelo George, Marianna Annunziatella, Stéphane Arnouts, Stephen Gwyn, Danilo Marchesini, Anna Sajina. 2025-05-29. The Growth of Galaxy Stellar Haloes Over $0.2 \leq z \leq 1.1$. https://arxiv.org/abs/2412.03662

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