Brad P. Holden

EVOLUTION OF THE COLOR-MAGNITUDE RELATION IN GALAXY CLUSTERS AT z ∼ 1 FROM THE ACS INTERMEDIATE REDSHIFT CLUSTER SURVEY

We apply detailed observations of the color-magnitude relation (CMR) with the Advanced Camera for Surveys on the Hubble Space Telescope to study galaxy evolution in eight clusters at z 1. The early-type red sequence is well defined and elliptical and lenticular galaxies lie on similar CMRs. We analyze CMR parameters—scatter, slope, and zero point—as a function of redshift, galaxy properties and cluster mass. For bright galaxies (MB – 21 mag). While the bright S0 population consistently shows larger scatter than the ellipticals, the scatter of the latter increases in the peripheral cluster regions. If we interpret these results as due to age differences, bright elliptical galaxies in cluster cores are, on average, older than S0 galaxies and peripheral elliptical galaxies (by about 0.5 Gyr, using a simple, single-burst solar metallicity stellar population model). The CMR zero point, slope, and scatter in the (U – B) z = 0 rest-frame show no significant evolution out to redshift z 1.3 or significant dependence on cluster mass. Two of our clusters display CMR zero points that are redder (by 2σ) than the average (U – B) z = 0 of our sample. We also analyze the fraction of morphological early-type and late-type galaxies on the red sequence. We find that, while in the majority of the clusters most (80% to 90%) of the CMR population is composed of early-type galaxies, in the highest-redshift, low-mass cluster of our sample, the CMR late-type/early-type fractions are similar (50%), with most of the late-type population composed of galaxies classified as S0/a. This trend is not correlated with the clusters X-ray luminosity, or with its velocity dispersion, and could be a real evolution with redshift.

Advanced Camera for Surveys Photometry of the Cluster RDCS 1252.9?2927: The Color-Magnitude Relation at z = 1.24

We investigate the color-magnitude (CM) relation of galaxies in the distant X-ray selected cluster RDCS 1252.9‐2927 at z = 1.24 using images obtained with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescopein the F775W and F850LP bandpasses. We select galaxies based on morphological classifications extending about 3.5 mag down the galaxy lumi nosity function, augmented by spectroscopic membership information. At the core of the cluster is an extensive early-type galaxy population surrounding a central pair of galaxies that show signs of dynamical interaction. The early-type population defines a tight sequence in the CM diagram, with an intrinsic scatter in observed (i775-z850) of 0.029 ± 0.007 mag based on 52 galaxies, or 0.024 ± 0.008 mag for ∼ 30 ellipticals. Simulations using the latest stellar popul ation models indicate an age

Evolution of the Color-Magnitude Relation in High-Redshift Clusters: Early-Type Galaxies in the Lynx Supercluster at z ~ 1.26

Color-magnitude relations (CMRs) have been derived in two high-redshift clusters, RX J0849+4452 and RX J0848+4453(withredshiftsofz ¼ 1:26and1.27,respectively),thatlieinthehighestredshiftclustersuperstructure known today, the Lynx Supercluster. The CMR was determined from ACS imaging in the WFC F775W (i775 )a nd F850LP (z850) filters combined with ground-based spectroscopy. Early-type cluster candidates have been identified according to the Postman et al. morphological classification. In both clusters the bright red early-type population defines atightCMR verysimilarin color,althoughthe two clusters presentdifferentX-rayluminositiesand shapes. The elliptical galaxy CMRs in RX J0849+4452 and RX J0848+4453 show an intrinsic (i775 � z850) color scatter of 0:026 � 0:012 and 0:024 � 0:015 mag, respectively, within 2 0 (� 1M pc atz ¼ 1:26) from the cluster X-ray emission centers. Simple modeling of the scatters using stellar population models from Bruzualand Charlotgives a meanluminosity-weightedaget > 2:5Gyr(zf > 2:75)andt > 2:6Gyr(zf > 2:8)forellipticalsinRXJ0849+4452 andRX J0848+4453,respectively.S0 galaxiesfollowtheellipticalCMR;theyshowlargerscattersabouttheCMR. The intrinsic scatter decreases and the CMR slopes are steeper at smaller radii, within both clusters. Within 1 0 from the cluster X-ray emission centers, elliptical CMR scatters imply a mean luminosity-weighted age t > 3: 2G yr (zf > 3:7). We conclude that old stellar populations in cluster elliptical galaxies are already in place at z ¼ 1:26, both in the more evolved cluster RX J0849+4452 and in its less evolved companion RX J0848+4453. Even at a look-back time of 9 Gyr, in the early merging and buildup of massive clusters, the bulk of the stellar content of the bright elliptical galaxy population was in place—apparently formed some 2.5 Gyr earlier at z � 3. Subject headingg galaxies: clusters: individual (RX J0848+4453, RX J0849+4452) — galaxies: elliptical and lenticular, cD — galaxies: evolution

z ~ 7 Galaxy Candidates from NICMOS Observations Over the HDF-South and the CDF-South and HDF-North Goods Fields

We use �88 arcmin 2 of deep (&26.5 mag at 5�) NICMOS data over the two GOODS fields and the HDF South to conduct a search for bright z & 7 galaxy candidates. This search takes advantage of an efficient preselection over 58 arcmin 2 of NICMOS H160-band data where only plausible z & 7 candidates are followed up with NICMOS J110-band observations. �248 arcmin 2 of deep groundbased near-infrared data (& 25.5 mag, 5�) is also considered in the search. In total, we report 15 z850-dropout candidates over this area – 7 of which are new to these search fields. Two possible z � 9 J110-dropout candidates are also found, but seem unlikely to correspond to z � 9 galaxies (given the estimated contamination levels). The present z � 9 search is used to set upper limits on the prevalence of such sources. Rigorous testing is undertaken to establish the level of contamination of our selections by photometric scatter, low mass stars, supernovae (SNe), and spurious sources. The estimated contamination rate of our z � 7 selection is �24%. Through careful simulations, the effective volume available to our z & 7 selections is estimated and used to establish constraints on the volume density of luminous (L ∗=3 , or � 21 mag) galaxies from these searches. We find that the volume density of luminous star-forming galaxies at z � 7 is 13 +85 × lower than at z � 4 and >25× lower (1�) at z � 9 than at z � 4. This is the most stringent constraint yet available on the volume density of & L ∗=3 galaxies at z � 9. The present wide-area, multi-field search limits cosmic variance to .20%. The evolution we find at the bright end of the UV LF is similar to that found from recent Subaru Suprime-Cam, HAWK-I or ERS WFC3/IR searches. The present paper also includes a complete summary of our final z � 7 z850-dropout sample (18 candidates) identified from all NICMOS observations to date (over the two GOODS fields, the HUDF, galaxy clusters).

Early-type Galaxies at z = 1.3. I. The Lynx Supercluster: Cluster and Groups at z = 1.3. Morphology and Color-Magnitude Relation

We confirm the detection of three groups in the Lynx supercluster, at z ≈ 1.3, through spectroscopic follow-up and X-ray imaging, and we give estimates for their redshifts and masses. We study the properties of the group galaxies compared to the two central clusters, RX J0849+4452 and RX J0848+4453. Using spectroscopic follow-up and multi-wavelength photometric redshifts, we select 89 galaxies in the clusters, of which 41 are spectroscopically confirmed, and 74 galaxies in the groups, of which 25 are spectroscopically confirmed. We morphologically classify galaxies by visual inspection, noting that our early-type galaxy (ETG) sample would have been contaminated at the 30%-40% level by simple automated classification methods (e.g., based on Sersic index). In luminosity-selected samples, both clusters and groups show high fractions of bulge-dominated galaxies with a diffuse component that we visually identified as a disk and which we classified as bulge-dominated spirals, e.g., Sas. The ETG fractions never rise above ≈50% in the clusters, which is low compared to the fractions observed in other massive clusters at z ≈ 1. In the groups, ETG fractions never exceed ≈25%. However, overall bulge-dominated galaxy fractions (ETG plus Sas) are similar to those observed for ETGs in clusters at z ~ 1. Bulge-dominated galaxies visually classified as spirals might also be ETGs with tidal features or merger remnants. They are mainly red and passive, and span a large range in luminosity. Their star formation seems to have been quenched before experiencing a morphological transformation. Because their fraction is smaller at lower redshifts, they might be the spiral population that evolves into ETGs. For mass-selected samples of galaxies with masses M > 10^(10.6) M_☉ within Σ > 500 Mpc^(–2), the ETG and overall bulge-dominated galaxy fractions show no significant evolution with respect to local clusters, suggesting that morphological transformations might occur at lower masses and densities. The ETG mass-size relation shows evolution toward smaller sizes at higher redshift in both clusters and groups, while the late-type mass-size relation matches that observed locally. When compared to the clusters, the group ETG red sequence shows lower zero points (at ~2σ) and larger scatters, both expected to be an indication of a younger galaxy population. However, we show that any allowed difference between the age in groups and clusters would be small when compared to the differences in age in galaxies of different masses.

The Rest-Frame K-Band Luminosity Function of Galaxies in Clusters to z = 1.3

We derive the rest-frame K-band luminosity function for galaxies in 32 clusters at 0.6 < z < 1.3 using deep 3.6 and 4.5 μm imaging from the Spitzer Space Telescope Infrared Array Camera. The luminosity functions approximate the stellar mass function of the cluster galaxies. Their dependence on redshift indicates that massive cluster galaxies (to the characteristic luminosity M^*_K) are fully assembled at least at z ~ 1.3 and that little significant accretion takes place at later times. The existence of massive, highly evolved galaxies at these epochs is likely to represent a significant challenge to theories of hierarchical structure formation where such objects are formed by the late accretion of spheroidal systems at z < 1.

The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey

This document is the Accepted Manuscript version of the following article: R. Paul Butler, et al, The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey, The Astronomical Journal, Vol 153 (5), 19 pp., published 13 April 2017. The Version of Record is available online at doi: https://doi.org/10.3847/1538-3881/aa66ca. Paper data available at: http://home.dtm.ciw.edu/ebps/data/.

SIX PLANETS ORBITING HD 219134

We present new, high-precision Doppler radial velocity (RV) data sets for the nearby K3V star HD 219134. The data include 175 velocities obtained with the HIRES Spectrograph at the Keck I Telescope, and 101 velocities obtained with the Levy Spectrograph at the Automated Planet Finder Telescope (APF) at Lick Observatory. Our observations reveal six new planetary candidates, with orbital periods of P=3.1, 6.8, 22.8, 46.7, 94.2 and 2247 days, spanning masses of msini=3.8, 3.5, 8.9, 21.3, 10.8 and 108 M_earth respectively. Our analysis indicates that the outermost signal is unlikely to be an artifact induced by stellar activity. In addition, several years of precision photometry with the T10 0.8~m automatic photometric telescope (APT) at Fairborn Observatory demonstrated a lack of brightness variability to a limit of ~0.0002 mag, providing strong support for planetary-reflex motion as the source of the radial velocity variations. The HD 219134 system, with its bright (V=5.6) primary provides an excellent opportunity to obtain detailed orbital characterization (and potentially follow-up observations) of a planetary system that resembles many of the multiple-planet systems detected by Kepler, and which are expected to be detected by NASAs forthcoming TESS Mission and by ESAs forthcoming PLATO Mission.

THE LICK-CARNEGIE EXOPLANET SURVEY: HD 32963—A NEW JUPITER ANALOG ORBITING A SUN-LIKE STAR

We present a set of 109 new, high-precision Keck/HIRES radial velocity (RV) observations for the solar-type star HD 32963. Our dataset reveals a candidate planetary signal with a period of 6.49

The HDUV survey: a revised assessment of the relationship between UV slope and dust attenuation for high-redshift galaxies

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