- ID:
- ivo://CDS.VizieR/J/MNRAS/432/2696
- Title:
- Galaxy luminosity function at z = 7-9
- Short Name:
- J/MNRAS/432/2696
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new determination of the ultraviolet (UV) galaxy luminosity function (LF) at redshift z=~7 and 8, and a first estimate at z=~9. An accurate determination of the form and evolution of the galaxy LF during this era is of key importance for improving our knowledge of the earliest phases of galaxy evolution and the process of cosmic reionization. Our analysis exploits to the full the new, deepest Wide Field Camera 3/infrared imaging from our Hubble Space Telescope (HST) Ultra-Deep Field 2012 (UDF12) campaign, with dynamic range provided by including a new and consistent analysis of all appropriate, shallower/wider area HST survey data. Our new measurement of the evolving LF at z=~7 to 8 is based on a final catalogue of =~600 galaxies, and involves a step-wise maximum-likelihood determination based on the photometric redshift probability distribution for each object; this approach makes full use of the 11-band imaging now available in the Hubble Ultra-Deep Field (HUDF), including the new UDF12 F140W data, and the latest Spitzer IRAC imaging. The final result is a determination of the z=~7 LF extending down to UV absolute magnitudes M_1500_=-16.75 (AB mag) and the z=~8 LF down to M_1500_=-17.00. Fitting a Schechter function, we find M_1500_^*^=-19.90^+0.23^_-0.28^, log{phi}^*^=-2.96^+0.18^_-0.23_ and a faint-end slope {alpha}=-1.90^+0.14^_-0.15_ at z=~7, and M_1500_^*^=-20.12^+0.37^_-0.48_, log{phi}^*^=-3.35^+0.28^_-0.47_ and {alpha}=-2.02^+0.22^_-0.23_ at z=~8. These results strengthen previous suggestions that the evolution at z>7 appears more akin to 'density evolution' than the apparent 'luminosity evolution' seen at z=~5-7. We also provide the first meaningful information on the LF at z=~9, explore alternative extrapolations to higher redshifts, and consider the implications for the early evolution of UV luminosity density. Finally, we provide catalogues (including derived z_phot_, M_1500_ and photometry) for the most robust z~6.5-11.9 galaxies used in this analysis. We briefly discuss our results in the context of earlier work and the results derived from an independent analysis of the UDF12 data based on colour-colour selection.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/128/163
- Title:
- Galaxy morphological classification
- Short Name:
- J/AJ/128/163
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present two new nonparametric methods for quantifying galaxy morphology: the relative distribution of the galaxy pixel flux values (the Gini coefficient or G) and the second-order moment of the brightest 20% of the galaxy's flux (M_20_). We test the robustness of G and M_20_ to decreasing signal-to-noise ratio (S/N) and spatial resolution and find that both measures are reliable to within 10% for images with average S/N per pixel greater than 2 and resolutions better than 1000 and 500pc, respectively. We have measured G and M_20_, as well as concentration (C), asymmetry (A), and clumpiness (S) in the rest-frame near-ultraviolet/optical wavelengths for 148 bright local "normal" Hubble-type galaxies (E-Sd) galaxies, 22 dwarf irregulars, and 73 0.05<z<0.25 ultraluminous infrared galaxies (ULIRGs).
- ID:
- ivo://CDS.VizieR/J/ApJ/631/85
- Title:
- Galaxy morphologies in the Hubble UDF
- Short Name:
- J/ApJ/631/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxies in the Hubble Ultra Deep Field (UDF) larger than 10 pixels (0.3") have been classified according to morphology, and their photometric properties are presented. There are 269 spiral, 100 elliptical, 114 chain, 126 double-clump, 97 tadpole, and 178 clump-cluster galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/1886
- Title:
- Galaxy morphologies with Illustris Simulation
- Short Name:
- J/MNRAS/454/1886
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study how optical galaxy morphology depends on mass and star formation rate (SFR) in the Illustris Simulation. To do so, we measure automated galaxy structures in 10808 simulated galaxies at z=0 with stellar masses 109.7<M*/M_{sun}_< 1012.3. We add observational realism to idealized synthetic images and measure non-parametric statistics in rest-frame optical and near-IR images from four directions. We find that Illustris creates a morphologically diverse galaxy population, occupying the observed bulge strength locus and reproducing median morphology trends versus stellar mass, SFR, and compactness. Morphology correlates realistically with rotation, following classification schemes put forth by kinematic surveys. Type fractions as a function of environment agree roughly with data. These results imply that connections among mass, star formation, and galaxy structure arise naturally from models matching global star formation and halo occupation functions when simulated with accurate methods. This raises a question of how to construct experiments on galaxy surveys to better distinguish between models. We predict that at fixed halo mass near 10^12^M_{sun}_, disc-dominated galaxies have higher stellar mass than bulge-dominated ones, a possible consequence of the Illustris feedback model. While Illustris galaxies at M*~10^11^M_{sun}_ have a reasonable size distribution, those at M*~10^10^M_{sun}_ have half-light radii larger than observed by a factor of 2. Furthermore, at M*~10^10.5^-10^11^M_{sun}_, a relevant fraction of Illustris galaxies have distinct 'ring-like' features, such that the bright pixels have an unusually wide spatial extent.
- ID:
- ivo://CDS.VizieR/J/AJ/134/1508
- Title:
- Galaxy morphology catalog
- Short Name:
- J/AJ/134/1508
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Careful inspection of large-scale photographs of Shapley-Ames galaxies seems to show a smooth transition between the morphological characteristics of galaxies located on the narrow red and on the broad blue sequences in the galaxian color-magnitude diagram. In other words, there does not appear to be a dichotomy between blue and red galaxies. Both the colors and the morphologies of galaxies are found to correlate strongly with their environments. Red and early-type Shapley-Ames galaxies are dominant in clusters, whereas blue late-type star-forming objects dominate the general field. Interestingly, the colors and morphologies of galaxies in small groups resemble the field and differ from those in clusters. As noted by Baade, the presence of dust and star formation are very closely correlated, except in a few galaxies that probably had unusual evolutionary histories. Over the entire range from S0 to Sc there is no significant difference between the integrated colors of normal and barred objects, suggesting that the formation of a bar does not significantly affect the stellar evolutionary history of a galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/506/1071
- Title:
- Galaxy morphology in 5 medium redshift clusters
- Short Name:
- J/A+A/506/1071
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Following the study presented in our previous paper, based on the Nordic Optical Telescope (NOT) sample, which consists of five clusters of galaxies within the redshift range 0.18<=z<=0.25 imaged in the central 0.5-2Mpc in very good seeing conditions, we have studied the quantitative morphology of their bright galaxy population. We analyzed the surface brightness profiles of the galaxy population in those clusters, after performing simulations in order to check the reliability of the fits. We also derived a quantitative morphological classification.
- ID:
- ivo://CDS.VizieR/J/AJ/122/621
- Title:
- Galaxy morphology in the CFRS
- Short Name:
- J/AJ/122/621
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The images of 229 galaxies in the Canada-France Redshift Survey have been classified on the DDO system. These observations were combined with previous classifications of galaxies with known redshifts in the Hubble Deep Field. The combined sample provides homogeneous morphological classifications for 425 galaxies of known redshift. The fraction of all galaxies that are of type E, S0, or E/S0 appears to remain approximately constant at ~17% over the redshift range 0.25<z<1.2. Over the same range, the fraction of irregular (Ir) galaxies increases from ~5% to ~12%. Part of this increase may be due to mild luminosity evolution of Ir galaxies. The frequency of mergers is found to rise by a factor of 2 or 3 over the redshift range covered by the present survey. These results are in qualitative agreement with those obtained previously by Brinchmann et al. (Cat. <J/ApJ/499/112>) using a coarser galaxy classification system.
- ID:
- ivo://CDS.VizieR/J/MNRAS/388/1537
- Title:
- Galaxy pairs from SDSS-DR2
- Short Name:
- J/MNRAS/388/1537
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the incidence of major mergers creating massive (M_star_>10^11^M_{sun}_) galaxies in present-day (z<=0.12) groups and clusters. Using a volume-limited sample of 845 groups with dark matter halo masses above 2.5x10^13^M_{sun}_, we isolate 221 galaxy pairs with <=1.5 r-band magnitude differences, <=30kpc projected separations and combined masses above 10^11^M_{sun}_. We fit the r-band images of each pair as the line-of-sight projection of symmetric models and identify 38 mergers by the presence of residual asymmetric structure associated with both progenitors, such as non-concentric isophotes, broad and diffuse tidal tails and dynamical friction wakes.
- ID:
- ivo://CDS.VizieR/J/ApJ/565/208
- Title:
- Galaxy pairs in the CNOC2 Redshift Survey
- Short Name:
- J/ApJ/565/208
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate redshift evolution in the galaxy merger and accretion rates, using a well-defined sample of 4184 galaxies with 0.12<=z<=0.55 and R_C_<=21.5. We identify 88 galaxies in close (5<=rp<=20h^-1^kpc) dynamical ({Delta}<=500km/s) pairs. These galaxies are used to compute global pair statistics, after accounting for selection effects resulting from the flux limit, k-corrections, luminosity evolution, and spectroscopic incompleteness.
1200. Galaxy properties at NGP
- ID:
- ivo://CDS.VizieR/VII/204
- Title:
- Galaxy properties at NGP
- Short Name:
- VII/204
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A two-color study of the galaxies detected on POSS-I in a 289deg^2^ region centered on the North Galactic Pole is presented. We use a variety of mapping techniques to characterize the large-scale spatial distribution of galaxies. The depth and sample size of this new survey allows, for the first time, the isolation of large photometric subsamples of galaxies in high- and low-density environments on the scale of superclusters. Our principal finding is a statistically significant difference between the mean photometric properties of these subsamples in the sense that galaxies in the high-density Coma and filament environments have redded colors and larger concentration indices than galaxies drawn from low-density interfilament regions. These results are in agreement with the known morphology-density relation.
