We study the structural evolution of massive galaxies by linking progenitors and descendants at a constant cumulative number density of n $_c$ = 1.4 { imes} 10$^{-4}$ Mpc$^{-3}$ to z ~{} 3.... Show moreWe study the structural evolution of massive galaxies by linking progenitors and descendants at a constant cumulative number density of n $_c$ = 1.4 { imes} 10$^{-4}$ Mpc$^{-3}$ to z ~{} 3. Structural parameters were measured by fitting Sérsic profiles to high-resolution CANDELS HST WFC3 J $_{125}$ and H $_{160}$ imaging in the UKIDSS-UDS at 1 {lt} z {lt} 3 and ACS I $_{814}$ imaging in COSMOS at 0.25 {lt} z {lt} 1. At a given redshift, we selected the HST band that most closely samples a common rest-frame wavelength so as to minimize systematics from color gradients in galaxies. At fixed n $_c$, galaxies grow in stellar mass by a factor of ~{}3 from z ~{} 3 to z ~{} 0. The size evolution is complex: galaxies appear roughly constant in size from z ~{} 3 to z ~{} 2 and then grow rapidly to lower redshifts. The evolution in the surface mass density profiles indicates that most of the mass at r {lt} 2 kpc was in place by z ~{} 2, and that most of the new mass growth occurred at larger radii. This inside-out mass growth is therefore responsible for the larger sizes and higher Sérsic indices of the descendants toward low redshift. At z {lt} 2, the effective radius evolves with the stellar mass as r$_e$ vpropM $^{2.0}$, consistent with scenarios that find dissipationless minor mergers to be a key driver of size evolution. The progenitors at z ~{} 3 were likely star-forming disks with r$_e$ ~{} 2 kpc, based on their low Sérsic index of n ~{} 1, low median axis ratio of b/a ~{} 0.52, and typical location in the star-forming region of the U - V versus V - J diagram. By z ~{} 1.5, many of these star-forming disks disappeared, giving rise to compact quiescent galaxies. Toward lower redshifts, these galaxies continued to assemble mass at larger radii and became the local ellipticals that dominate the high-mass end of the mass function at the present epoch. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Show less
We present a new two-color algorithm, the ''Stellar Bump Sequence'' (SBS), that is optimized for robustly identifying candidate high-redshift galaxy clusters in combined wide-field optical and mid... Show moreWe present a new two-color algorithm, the ''Stellar Bump Sequence'' (SBS), that is optimized for robustly identifying candidate high-redshift galaxy clusters in combined wide-field optical and mid-infrared (MIR) data. The SBS algorithm is a fusion of the well-tested cluster red-sequence method of Gladders {amp} Yee with the MIR 3.6 {$μ$}m-4.5 {$μ$}m cluster detection method developed by Papovich. As with the cluster red-sequence method, the SBS identifies candidate overdensities within 3.6 {$μ$}m-4.5 {$μ$}m color slices, which are the equivalent of a rest-frame 1.6 {$μ$}m stellar bump ''red-sequence.'' In addition to employing the MIR colors of galaxies, the SBS algorithm incorporates an optical/MIR (z'-3.6 {$μ$}m) color cut. This cut effectively eliminates foreground 0.2 {lt}z {lt} 0.4 galaxies which have 3.6 {$μ$}m-4.5 {$μ$}m colors that are similarly red as z {gt} 1.0 galaxies and add noise when searching for high-redshift galaxy overdensities. We demonstrate using the z ~{} 1 GCLASS cluster sample that similar to the red sequence, the stellar bump sequence appears to be a ubiquitous feature of high-redshift clusters, and that within that sample the color of the stellar bump sequence increases monotonically with redshift and provides photometric redshifts accurate to {$Delta$}z = 0.05. We apply the SBS method in the XMM-LSS SWIRE field and show that it robustly recovers the majority of confirmed optical, MIR, and X-ray-selected clusters at z {gt} 1.0 in that field. Lastly, we present confirmation of SpARCS J022427-032354 at z = 1.63, a new cluster detected with the method and confirmed with 12 high-confidence spectroscopic redshifts obtained using FORS2 on the Very Large Telescope. We conclude with a discussion of future prospects for using the algorithm. Show less
Patel, S.G.; Dokkum, P.; Franx, M.; Quadri, R.; Muzzin, A.V.; Marchesini, D.; ... ; Stefanon, M. 2013
We study the structural evolution of massive galaxies by linking progenitors and descendants at a constant cumulative number density of n $_c$ = 1.4 { imes} 10$^{-4}$ Mpc$^{-3}$ to z ~{} 3.... Show moreWe study the structural evolution of massive galaxies by linking progenitors and descendants at a constant cumulative number density of n $_c$ = 1.4 { imes} 10$^{-4}$ Mpc$^{-3}$ to z ~{} 3. Structural parameters were measured by fitting Sérsic profiles to high-resolution CANDELS HST WFC3 J $_{125}$ and H $_{160}$ imaging in the UKIDSS-UDS at 1 {lt} z {lt} 3 and ACS I $_{814}$ imaging in COSMOS at 0.25 {lt} z {lt} 1. At a given redshift, we selected the HST band that most closely samples a common rest-frame wavelength so as to minimize systematics from color gradients in galaxies. At fixed n $_c$, galaxies grow in stellar mass by a factor of ~{}3 from z ~{} 3 to z ~{} 0. The size evolution is complex: galaxies appear roughly constant in size from z ~{} 3 to z ~{} 2 and then grow rapidly to lower redshifts. The evolution in the surface mass density profiles indicates that most of the mass at r {lt} 2 kpc was in place by z ~{} 2, and that most of the new mass growth occurred at larger radii. This inside-out mass growth is therefore responsible for the larger sizes and higher Sérsic indices of the descendants toward low redshift. At z {lt} 2, the effective radius evolves with the stellar mass as r$_e$ vpropM $^{2.0}$, consistent with scenarios that find dissipationless minor mergers to be a key driver of size evolution. The progenitors at z ~{} 3 were likely star-forming disks with r$_e$ ~{} 2 kpc, based on their low Sérsic index of n ~{} 1, low median axis ratio of b/a ~{} 0.52, and typical location in the star-forming region of the U - V versus V - J diagram. By z ~{} 1.5, many of these star-forming disks disappeared, giving rise to compact quiescent galaxies. Toward lower redshifts, these galaxies continued to assemble mass at larger radii and became the local ellipticals that dominate the high-mass end of the mass function at the present epoch. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Show less
Muzzin, A.V.; Marchesini, D.; Stefanon, M.; Franx, M.; McCracken, H.; Milvang-Jensen, B.; ... ; Dokkum, P. van 2013
We present measurements of the stellar mass functions (SMFs) of star-forming and quiescent galaxies to z = 4 using a sample of 95,675 K$_s$ -selected galaxies in the COSMOS/UltraVISTA field. The... Show moreWe present measurements of the stellar mass functions (SMFs) of star-forming and quiescent galaxies to z = 4 using a sample of 95,675 K$_s$ -selected galaxies in the COSMOS/UltraVISTA field. The SMFs of the combined population are in good agreement with previous measurements and show that the stellar mass density of the universe was only 50%, 10%, and 1% of its current value at z ~{} 0.75, 2.0, and 3.5, respectively. The quiescent population drives most of the overall growth, with the stellar mass density of these galaxies increasing as {$ρ$}$_{star}$vprop(1 + z)$^{–4.7 ± 0.4}$ since z = 3.5, whereas the mass density of star-forming galaxies increases as {$ρ$}$_{star}$vprop(1 + z)$^{–2.3 ± 0.2}$. At z {gt} 2.5, star-forming galaxies dominate the total SMF at all stellar masses, although a non-zero population of quiescent galaxies persists to z = 4. Comparisons of the K$_s$ -selected star-forming galaxy SMFs with UV-selected SMFs at 2.5 {lt} z {lt} 4 show reasonable agreement and suggest that UV-selected samples are representative of the majority of the stellar mass density at z {gt} 3.5. We estimate the average mass growth of individual galaxies by selecting galaxies at fixed cumulative number density. The average galaxy with log(M $_{star}$/M $_{☉}$) = 11.5 at z = 0.3 has grown in mass by only 0.2 dex (0.3 dex) since z = 2.0 (3.5), whereas those with log(M $_{star}$/M $_{☉}$) = 10.5 have grown by {gt}1.0 dex since z = 2. At z {lt} 2, the time derivatives of the mass growth are always larger for lower-mass galaxies, which demonstrates that the mass growth in galaxies since that redshift is mass-dependent and primarily bottom-up. Lastly, we examine potential sources of systematic uncertainties in the SMFs and find that those from photo-z templates, stellar population synthesis modeling, and the definition of quiescent galaxies dominate the total error budget in the SMFs. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under ESO programme ID 179.A-2005 and on data products produced by TERAPIX and the Cambridge Astronomy Survey Unit on behalf of the UltraVISTA consortium. Show less
Patel, S.G.; Fumagalli, M.; Franx, M.; Dokkum, P. van; Wel, A. van der; Leja, J.; ... ; Rix, H. 2013
We follow the structural evolution of star-forming galaxies (SFGs) like the Milky Way by selecting progenitors to z ~{} 1.3 based on the stellar mass growth inferred from the evolution of the star... Show moreWe follow the structural evolution of star-forming galaxies (SFGs) like the Milky Way by selecting progenitors to z ~{} 1.3 based on the stellar mass growth inferred from the evolution of the star-forming sequence. We select our sample from the 3D-HST survey, which utilizes spectroscopy from the HST/WFC3 G141 near-IR grism and enables precise redshift measurements for our sample of SFGs. Structural properties are obtained from Sérsic profile fits to CANDELS WFC3 imaging. The progenitors of z = 0 SFGs with stellar mass M = 10$^{10.5}$ M $_{☉}$ are typically half as massive at z ~{} 1. This late-time stellar mass growth is consistent with recent studies that employ abundance matching techniques. The descendant SFGs at z ~{} 0 have grown in half-light radius by a factor of ~{}1.4 since z ~{} 1. The half-light radius grows with stellar mass as r$_e$ vpropM $^{0.29}$. While most of the stellar mass is clearly assembling at large radii, the mass surface density profiles reveal ongoing mass growth also in the central regions where bulges and pseudobulges are common features in present day late-type galaxies. Some portion of this growth in the central regions is due to star formation as recent observations of H{$α$} maps for SFGs at z ~{} 1 are found to be extended but centrally peaked. Connecting our lookback study with galactic archeology, we find the stellar mass surface density at R = 8 kpc to have increased by a factor of ~{}2 since z ~{} 1, in good agreement with measurements derived for the solar neighborhood of the Milky Way. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Show less
Noble, A.; Webb, T.; Muzzin, A.V.; Wilson, G.; Yee, H.; Burg, R.F.J. van der 2013
We present an infrared study of a z = 0.872 cluster, SpARCS J161314+564930, with the primary aim of distinguishing the dynamical histories of spectroscopically confirmed star-forming members to... Show moreWe present an infrared study of a z = 0.872 cluster, SpARCS J161314+564930, with the primary aim of distinguishing the dynamical histories of spectroscopically confirmed star-forming members to assess the role of cluster environment. We utilize deep MIPS imaging and a mass-limited sample of 85 spectroscopic members to identify 16 24 {$μ$}m bright sources within the cluster, and measure their 24 {$μ$}m star formation rates (SFRs) down to ~{}6 M $_{⊙}$ yr$^{-1}$. Based on their line-of-sight velocities and stellar ages, MIPS cluster members appear to be an infalling population that was recently accreted from the field with minimal environmental dependency on their star formation. However, we identify a double-sequenced distribution of star-forming galaxies among the members, with one branch exhibiting declining specific SFRs with mass. The members along this sub-main sequence contain spectral features suggestive of passive galaxies. Using caustic diagrams, we kinematically identify these galaxies as a virialized and/or backsplash population. Moreover, we find a mix of dynamical histories at all projected radii, indicating that standard definitions of environment (i.e., radius and density) are contaminated with recently accreted interlopers, which could contribute to a lack of environmental trends for star-forming galaxies. A cleaner narrative of their dynamical past begins to unfold when using a proxy for accretion histories through profiles of constant (r/r $_{200}$) { imes} ({$Delta$}v/{$σ$}$_{ v }$); galaxies accreted at earlier times possess lower values of (r/r $_{200}$) { imes} ({$Delta$}v/{$σ$}$_{ v }$) with minimal contamination from the distinct infalling population. Therefore, adopting a time-averaged definition for density (as traced by accretion histories) rather than an instantaneous density yields a depressed specific SFR within the dynamical cluster core. Show less
Aims: We present the stellar mass functions (SMFs) of star-forming and quiescent galaxies from observations of ten rich, red-sequence selected, clusters in the Gemini Cluster Astrophysics... Show moreAims: We present the stellar mass functions (SMFs) of star-forming and quiescent galaxies from observations of ten rich, red-sequence selected, clusters in the Gemini Cluster Astrophysics Spectroscopic Survey (GCLASS) in the redshift range 0.86 {lt} z {lt} 1.34. We compare our results with field measurements at similar redshifts using data from a K$_s$-band selected catalogue of the COSMOS/UltraVISTA field. Methods: We construct a K$_s$-band selected multi-colour catalogue for the clusters in eleven photometric bands covering u-8 {$μ$}m, and estimate photometric redshifts and stellar masses using spectral energy distribution fitting techniques. To correct for interlopers in our cluster sample, we use the deep spectroscopic component of GCLASS, which contains spectra for 1282 identified cluster and field galaxies taken with Gemini/GMOS. This allowed us to correct cluster number counts from a photometric selection for false positive and false negative identifications. Both the photometric and spectroscopic samples are sufficiently deep that we can probe the SMF down to masses of 10$^{10}$ M$_{⊙}$. Results: We distinguish between star-forming and quiescent galaxies using the rest-frame U - V versus V - J diagram, and find that the best-fitting Schechter parameters {$α$} and M$^{∗}$ are similar within the uncertainties for these galaxy types within the different environments. However, there is a significant difference in the shape and normalisation of the total SMF between the clusters and the field sample. This difference in the total SMF is primarily a reflection of the increased fraction of quiescent galaxies in high-density environments. We apply a simple quenching model that includes components of mass- and environment-driven quenching, and find that in this picture 45$_{-3}$$^{+4}$% of the star-forming galaxies, which normally would be forming stars in the field, are quenched by the cluster. Conclusions: If galaxies in clusters and the field quench their star formation via different mechanisms, these processes have to conspire in such a way that the shapes of the quiescent and star-forming SMF remain similar in these different environments. Appendices are available in electronic form at http://www.aanda.orgShow less
Muzzin, A.V.; Labbé, I.F.L.; Franx, M.; Dokkum, P. van; Holt, J.; Szomoru, D.; ... ; Milvang-Jensen, B. 2012
