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تسجيل مستخدم جديدThe Galaxy-Halo Connection for $1.5lesssim zlesssim5$ as revealed by the emph{Spitzer} Matching survey of the UltraVISTA ultra-deep Stripes
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William Cowley
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The emph{Spitzer} Matching Survey of the UltraVISTA ultra-deep Stripes (SMUVS) provides unparalleled depth at $3.6$ and $4.5$~$mu$m over $sim0.66$~deg$^2$ of the COSMOS field, allowing precise photometric determinations of redshift and stellar mass. From this unique dataset we can connect galaxy samples, selected by stellar mass, to their host dark matter halos for $1.5<z<5.0$, filling in a large hitherto unexplored region of the parameter space. To interpret the observed galaxy clustering we utilize a phenomenological halo model, combined with a novel method to account for uncertainties arising from the use of photometric redshifts. We find that the satellite fraction decreases with increasing redshift and that the clustering amplitude (e.g., comoving correlation length / large-scale bias) displays monotonic trends with redshift and stellar mass. Applying $Lambda$CDM halo mass accretion histories and cumulative abundance arguments for the evolution of stellar mass content we propose pathways for the coevolution of dark matter and stellar mass assembly. Additionally, we are able to estimate that the halo mass at which the ratio of stellar to halo mass is maximized is $10^{12.5_{-0.08}^{+0.10}}$~M$_{odot}$ at $zsim2.5$. This peak halo mass is here inferred for the first time from stellar mass-selected clustering measurements at $zgtrsim2$, and implies mild evolution of this quantity for $zlesssim3$, consistent with constraints from abundance-matching techniques.
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The Spitzer Matching Survey of the UltraVISTA Ultra-deep Stripes (SMUVS) has obtained the largest ultra-deep Spitzer maps to date in a single field of the sky. We considered the sample of about 66,000 SMUVS sources at $z=2-6$ to investigate the evolu
tion of dusty and non-dusty galaxies with stellar mass through the analysis of the galaxy stellar mass function (GSMF). We further divide our non-dusty galaxy sample with rest-frame optical colours to isolate red quiescent (`passive) galaxies. At each redshift, we identify a characteristic stellar mass in the GSMF above which dusty galaxies dominate, or are at least as important as non-dusty galaxies. Below that stellar mass, non-dusty galaxies comprise about 80% of all sources, at all redshifts except at $z=4-5$. The percentage of dusty galaxies at $z=4-5$ is unusually high: 30-40% for $M_{*}=10^9 - 10^{10.5} , rm M_odot$ and $>80%$ at $M_*>10^{11} , rm M_odot$, which indicates that dust obscuration is of major importance in this cosmic period. The overall percentage of massive ($log_{10} (M_*/M_odot)>10.6$) galaxies that are quiescent increases with decreasing redshift, reaching $>30%$ at $zsim2$. Instead, the quiescent percentage among intermediate-mass galaxies (with $log_{10} (M_*/M_odot)=9.7-10.6$) stays roughly constant at a $sim 10%$ level. Our results indicate that massive and intermediate-mass galaxies clearly have different evolutionary paths in the young Universe, and are consistent with the scenario of galaxy downsizing.
In recent years, massive new spectroscopic data sets, such as the over half million stellar spectra obtained during the course of SDSS (in particular its sub-survey SEGUE), have provided the quantitative detail required to formulate a coherent story
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