The FENIKS Survey: Stellar-Halo Mass Relationship of Central and Satellite Galaxies in UDS and COSMOS at 0.2 < z < 4.5

Introduction to the show: ident: Astrophysics Radio. Generated commentary on the latest astrophysics papers.

Vera: We're looking at the paper: "The FENIKS Survey".

Jocelyn: Here's the gist of the paper. The gist The FENIKS Survey presents a comprehensive analysis of the observed Stellar-to-Halo mass relationship (SHMR) spanning redshifts from 0.2 to 4.5 using galaxy clustering and abundance measurements from two large photometric catalogs, COSMOS and UDS We present a comprehensive analysis of the observed Stellar-to-Halo mass relationship (SHMR) spanning redshifts from 0.2 to 4.5 using galaxy clustering and abundance measurements from two large photometric catalogs, COSMOS and UDS How it works The study introduces a novel halo occupation distribution (HOD) fitting approach called “smooth-z” whereby HOD parameters between neighboring z-bins are connected via physically motivated continuity (smoothing) priors To translate these measurements into the SHMR, we introduce a novel halo occupation distribution (HOD) fitting approach (“smooth-z”) whereby HOD parameters between neighboring z-bins are connected via physically motivated continuity (smoothing) priors This method allows for joint fitting of galaxy clustering and abundance data across all redshifts by imposing smooth continuity priors on the redshift evolution of the HOD parameters Another novel aspect of this work is to jointly fit the galaxy clustering and abundance data in the entire redshift range of 0.2 < z < 4.5 by imposing smooth continuity priors on the redshift evolution of the HOD parameters This approach allows us to leverage the wealth of information contained within the clustering and abundance measurements at lower redshift spanning wider dynamical ranges in stellar mass, by connecting them to higher redshift via smooth redshift evolution of the HOD parameters This allowed dramatically reducing the uncertainties in SHMR at z > 2.5, giving a much clearer picture of SHMR evolution out to z = 4.5 Key Findings on Stellar-Halo Mass Relationship The research finds that the halo mass with peak integrated star-forming efficiency (SFE), Mpeak h remains constant within ∼ 10 12.2 − 10 12.4 M⊙ throughout the redshifts probed We find that the halo mass with peak integrated star-forming efficiency (SFE), Mpeak h remains constant within ∼ 10 12.2 − 10 12.4 M⊙ throughout the redshifts probed Furthermore, if they had relied on COSMOS alone, Mpeak h would be systematically lower by up to ∼ 0.15 dex at z < 1.5, highlighting the importance of mitigating cosmic variance Furthermore, we show that if we had relied on COSMOS alone (as opposed to COSMOS+UDS), as has been done by many preceding studies, Mpeak h would be systematically lower by up to ∼ 0.15 dex at z Evolution of Star Formation Efficiency (SFE) The study shows that if they had relied on COSMOS alone, Mpeak h would be systematically lower by up to ∼ 0.15 dex at z < 1.5, highlighting the importance of mitigating cosmic variance Furthermore, we show that if we had relied on COSMOS alone (as opposed to COSMOS+UDS), as has been done by many preceding studies, Mpeak h would be systematically lower by up to ∼ 0.15 dex at z The peak integrated star-forming efficiency (SFE) is found to occur in a narrow channel of Mpeak h ∼ 10 12.2 M⊙ − 10 12.4 M⊙ out to z = 4.5, indicating tight coupling between halo mass assembly and galaxy stellar mass assembly, and that quenching strongly depends on halo mass Peak integrated star formation occurs in a narrow channel of Mpeak h ∼ 10 12.2 M⊙ − 10 12.4 M⊙ out to z = 4.5, indicating tight coupling between halo mass assembly and galaxy stellar mass assembly, and that quenching strongly depends on halo mass Evolution of Central and Satellite Contributions Beyond halo masses of about ∼ 10 12.5 M⊙, depending on redshift, the contribution of satellites to the total stellar mass budget of the halo starts to become noticeable Beyond halo masses of about ∼ 10 12.5 M⊙, depending on redshift, the contribution of satellites to the total stellar mass budget of the halo starts to become noticeable The total (central+satellite) SHMR shows that beyond Mh ∼ 10 13.6 M⊙, satellites take over beyond Mh ∼ 10 13.6 M⊙ in the group and cluster-scale halos Beyond Mh ∼ 10 13.6 M⊙, the central galaxies account for a smaller and smaller fraction of the total stellar mass in halos, and the satellites take over beyond Mh ∼ 10 13.6 M⊙ in the group and cluster-scale halos The fraction of mass in satellites, fsat generally increases with decreasing redshift and stellar mass thresholds The fraction of mass in satellites, fsat generally increases with decreasing redshift and stellar mass thresholds Impact of Data Combination The use of two large fields (UDS in conjunction with COSMOS) greatly mitigated the effect of cosmic variance on Mpeak h evolution, and in doing so we found a much weaker downsizing signal throughout the redshifts probed The use of two large fields (UDS in conjunction with COSMOS) greatly mitigated the effect of cosmic variance on Mpeak h evolution, and in doing so we found a much weaker downsizing signal throughout the redshifts probed The resulting best-fit χ squared for the “smooth-z” fit is 2.46, where the degrees of freedom, DOF = 472 = 571 (number of data points within all z-bins) - 99 (11×9 HOD parameters within all z-bins) The reduced best-fit χ squared for the “smooth-z” fit, χ 2 red,smooth−z = 2.46, where the degrees of freedom, DOF = 472 = 571 (number of data points within all z-bins) - 99 (11×9 HOD parameters within all z-bins) The evolution of SHMR has imprints of various physical processes integrated over halos’ lifetimes such as cold gas flows towards the centers of halos giving rise to star formation, stellar/dark matter halo mass growth due to mergers, and on the flip side, the feedback effects that heat up or eject the gas out of galaxies quenching star formation The evolution of SHMR has imprints of various physical processes integrated over halos’ lifetimes such as cold gas flows towards the centers of halos giving rise to star formation, stellar/dark matter halo mass growth due to mergers, and on the flip side, the feedback effects that heat up or eject the gas out of galaxies quenching star formation The most massive halos assemble their stellar mass first followed by lesser and lesser massive halos most massive halos and galaxies observed within the lowest z-bin (z ∼ 0.35) accumulate their stellar mass first followed by progressively lighter systems The study concludes that the halo mass with peak integrated star-forming efficiency (SFE), Mpeak h evolves very little: it stays between ∼ 10 12.2M⊙ and ∼ 10 12.4M⊙ We show that the halo mass with peak integrated star-forming efficiency (SFE), Mpeak h evolves very little: it stays between ∼ 10 12.2M⊙ and ∼ 10 12.4M⊙ The total stellar mass locked up in halos less massive than Mh ∼ 10 12 M⊙ is dominated by central galaxies, whereas satellites dominate the stellar mass budget beyond Mh ∼ 10 13 M⊙ in group and cluster scale halos The total stellar mass locked up in halos less massive than Mh ∼ 10 12M⊙ is dominated by central galaxies, whereas satellites dominate the stellar mass budget beyond Mh ∼ 10 13M⊙ in group and cluster scale halos The conditional satellite SMFs have a classic SMF shape with a power law at low masses, ‘knee’ at intermediate masses, beyond which it declines sharply Satellites’ conditional SMFs, however, depend much more weakly on halo mass; satellites are equally scattered across Mh = 10 11.5 − 10 13.5M⊙ at M∗ ≲ 10 10 M⊙ The fraction of mass in satellites, fsat generally increases with decreasing redshift and stellar mass thresholds The fraction of mass in satellites, fsat generally increases with decreasing redshift and stellar mass thresholds The hierarchy of SFE in halos with redshift is shown to be a clear sign of downsizing (Cowie et al.

Paper summary: Vera: To summarize, the FENIKS Survey paper presents a comprehensive analysis of the observed Stellar-Halo Mass Relationship spanning redshifts from zero point two to four point five using galaxy clustering and abundance measurements from two large photometric catalogs, COSMOS and UDS > <ref:2411.04256#pg1>

Jocelyn: They introduce this novel halo occupation distribution fitting approach called "smooth- z " where they connect HOD parameters between neighboring z-bins using physically motivated continuity priors >

Subrahmanyan: The main claim is that by doing this, they can leverage the wealth of information from both clustering and abundance data across all redshifts to break degeneracies and get a robust estimate of the SHMR within the framework of Halo occupation distribution modeling >

Vera: They find that Mpeak h remains constant within about ten twelve point two minus ten twelve point four solar masses throughout the redshifts they probed, which suggests a tight coupling between halo mass assembly and galaxy stellar mass assembly >

Jocelyn: They also show that if you only relied on COSMOS alone, Mpeak h would be systematically lower by up to about zero point one five dex at redshifts less than one point five >

Subrahmanyan: The paper concludes that the evolution of the SHMR has imprints of various physical processes integrated over halos’ lifetimes, like cold gas flows giving rise to star formation and feedback effects quenching star formation >

Conclusion: Vera: So, looking at this title, "The FENIKS Survey: Stellar-Halo Mass Relationship of Central and Satellite Galaxies in UDS and COSMOS at zero point two < z < four point five," it really captures the scope of what they did with these two massive datasets > <ref:2411.04256#pg1,The FENIKS Survey: Stellar-Halo Mass Relationship of Central and Satellite Galaxies>

Jocelyn: It's important to think about how this study addresses the question of whether the observed evolution of galaxy properties is driven by things happening inside halos or if it's something else entirely >

Subrahmanyan: Ultimately, this work suggests that the hierarchy of star formation efficiency in halos with redshift is a clear sign of downsizing, meaning the most massive halos assemble their stellar mass first, followed by progressively lighter systems accumulating mass later >