Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. AbstractWe study a large galaxy sample from the Spitzer Matching Survey of the UltraVISTA ultra-deep Stripes (SMUVS) to search for sources with enhanced 3.6 m m fluxes indicative of strong Hα emission at z 3.9 4.9 = -. We find that the percentage of "Hα excess" sources reaches 37%-40% for galaxies with stellar masses M M log 9 10

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 evolution of dusty and non-dusty galaxies with stellar mass through the analysis of the galaxy stellar mass function (GSMF), extending previous analyses about one decade in stellar mass and up to z = 6. 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 M and > 80% at M * > 10 11 M , which indicates that dust obscuration is of major importance in this cosmic period. The overall percentage of massive (log 10 (M * /M ) > 10.6) galaxies that are quiescent increases with decreasing redshift, reaching > 30% at z ∼ 2. Instead, the quiescent percentage among intermediate-mass galaxies (with log 10 (M * /M ) = 9.7 − 10.6) stays roughly constant at a ∼ 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.

We report the discovery of a Multi Unit Spectroscopic Explorer (MUSE) galaxy group at z = 4.32 lensed by the massive galaxy cluster ACT-CL J0102-4915 (aka El Gordo) at z = 0.87, associated with a 1.2 mm source that is at a 2.07 ± 0.88 kpc projected distance from one of the group galaxies. Three images of the whole system appear in the image plane. The 1.2 mm source has been detected within the Atacama Large Millimetre/submillimetre Array (ALMA) Lensing Cluster Survey (ALCS). As this ALMA source is undetected at wavelengths λ < 2 μm, its redshift cannot be independently determined, however, the three lensing components indicate that it belongs to the same galaxy group at z = 4.32. The four members of the MUSE galaxy group have low to intermediate stellar masses (∼10 7 -10 10 M e ) and star formation rates (SFRs) of 0.4-24 M e yr −1 , resulting in high specific SFRs (sSFRs) for two of them, which suggest that these galaxies are growing fast (with stellar mass doubling times of only ∼2 × 10 7 yr). This high incidence of starburst galaxies is likely a consequence of interactions within the galaxy group, which is compact and has high velocity dispersion. Based on the magnification-corrected sub-/ millimeter continuum flux density and estimated stellar mass, we infer that the ALMA source is classified as an ordinary ultra-luminous infrared galaxy (with associated dust-obscured SFR ∼ 200-300 M e yr −1 ) and lies on the star formation main sequence. This reported case of an ALMA/MUSE group association suggests that some presumably isolated ALMA sources are in fact signposts of richer star-forming environments at high redshifts.

This paper describes new deep 3.6 and 4.5 µm imaging of three UltraVISTA near-infrared survey stripes within the COSMOS field. The observations were carried out with Spitzer's Infrared Array Camera (IRAC) for the Spitzer Matching Survey of the Ultra-VISTA Deep Stripes (SMUVS). In this work we present our data reduction techniques, and document the resulting mosaics, coverage maps, and catalogs in both IRAC passbands for the three easternmost UltraVISTA survey stripes, covering a combined area of about 0.66 deg 2 , of which 0.45 deg 2 have at least 20 hr integration time. SMUVS reaches point-source sensitivities of about 25.0 AB mag (0.13 µJy) at both 3.6 and 4.5 µm with a significance of 4σ, accounting for both survey sensitivity and source confusion. To this limit the SMUVS catalogs contain a total of ∼350,000 sources, each of which is detected significantly in at least one IRAC band. Because of its uniform and high sensitivity, relatively large area coverage, and the wide array of ancillary data available in COSMOS, the SMUVS survey will be useful for a large number of cosmological investigations. We make all images and catalogues described herein publicly available via the Spitzer Science Center.

The Spitzer Matching Survey of the UltraVISTA ultra-deep Stripes (SMUVS) provides unparalleled depth at 3.6 and 4.5 µm over ∼ 0.66 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 ΛCDM 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 +0.10 −0.08 M at z ∼ 2.5. This peak halo mass is here inferred for the first time from stellar mass-selected clustering measurements at z 2, and implies mild evolution of this quantity for z 3, consistent with constraints from abundance-matching techniques.