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Stefanon, Mauro,Yan, Haojing,Mobasher, Bahram,Barro, Guillermo,Donley, Jennifer L.,Fontana, Adriano,Hemmati, Shoubaneh,Koekemoer, Anton M.,Lee, BoMee,Lee, Seong-Kook,Nayyeri, Hooshang,Peth, Michael,Pf Published by the University of Chicago Press for t 2017 The Astrophysical journal Supplement series Vol.229 No.2
<P>We present a 0.4-8 mu m multi-wavelength photometric catalog in the Extended Groth Strip (EGS) field. This catalog is built on the Hubble Space Telescope (HST) WFC3 and ACS data from the Cosmic Assembly Nearinfrared Deep Extragalactic Legacy Survey (CANDELS), and it incorporates the existing HST data from the Allwavelength Extended Groth strip International Survey (AEGIS) and the 3D-HST program. The catalog is based on detections in the F160W band reaching a depth of F160W. =. 26.62 AB (90% completeness, point sources). It includes the photometry for 41,457 objects over an area of approximate to 206 arcmin(2) in the following bands: HST/ACS F606W and F814W; HST WFC3 F125W, F140W, and F160W; Canada-France-Hawaii Telescope (CFHT)/ Megacam u*, g', r', i' and z'; CFHT/WIRCAM J, H,. and KS; Mayall/NEWFIRM J1, J2, J3, H1, H2, and K; Spitzer IRAC 3.6, 4.5, 5.8, and 8.0 mu m. We are also releasing value-added catalogs that provide robust photometric redshifts and stellar mass measurements. The catalogs are publicly available through the CANDELS repository.</P>
Rutkowski, Michael J.,Jeong, Hyunjin,Cohen, Seth H.,Kaviraj, Sugata,Windhorst, Rogier A.,Ryan Jr., Russell E.,Koekemoer, Anton,Yi, Sukyoung K.,Hathi, Nimish P.,Dopita, Michael A. IOP Publishing 2014 The Astrophysical journal Vol.796 No.2
<P>We present an analysis of the stellar populations of 102 visually selected early-type galaxies (ETGs) with spectroscopic redshifts (0.35 less than or similar to z less than or similar to 1.5) from observations in the Early Release Science program with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST). We fit one-and two-component synthetic stellar models to the ETGs UV-optical-near-IR spectral energy distributions and find that a large fraction (similar to 40%) are likely to have experienced a minor (f(YC) less than or similar to 10% of stellar mass) burst of recent (t(YC) less than or similar to 1 Gyr) star formation. The measured age and mass fraction of the young stellar populations do not strongly trend with measurements of galaxy morphology. We note that massive (M > 10(10.5) M-circle dot) recent star-forming ETGs appear to have larger sizes. Furthermore, high-mass, quiescent ETGs identified with likely companions populate a distinct region in the size-mass parameter space, in comparison with the distribution of massive ETGs with evidence of recent star formation (RSF). We conclude that both mechanisms of quenching star formation in disk-like ETGs and (gas-rich, minor) merger activity contribute to the formation of young stars and the size-mass evolution of intermediate redshift ETGs. The number of ETGs for which we have both HST WFC3 panchromatic (especially UV) imaging and spectroscopically confirmed redshifts is relatively small, therefore, a conclusion about the relative roles of both of these mechanisms remains an open question.</P>
STUDYING LARGE- AND SMALL-SCALE ENVIRONMENTS OF ULTRAVIOLET LUMINOUS GALAXIES
Basu-Zych, Antara R.,Schiminovich, David,Heinis, Sebastien,Overzier, Roderik,Heckman, Tim,Zamojski, Michel,Ilbert, Olivier,Koekemoer, Anton M.,Barlow, Tom A.,Bianchi, Luciana,Conrow, Tim,Donas, Jose,F IOP Publishing 2009 The Astrophysical journal Vol.699 No.2
EVOLUTION OF STAR FORMATION PROPERTIES OF HIGH-REDSHIFT CLUSTER GALAXIES SINCE<i>z</i>= 2
Lee, Seong-Kook,Im, Myungshin,Kim, Jae-Woo,Lotz, Jennifer,McPartland, Conor,Peth, Michael,Koekemoer, Anton IOP Publishing 2015 The Astrophysical journal Vol.810 No.2
<P>Using a stellar mass-limited sample of similar to 46,600 galaxies (M-* > 10(9.1)M(circle dot)) at 0.5 < z < 2, we show that the stellar mass, rather than the environment, is the main parameter controlling quenching of star formation in galaxies with M-* > 10(10)M(circle dot) out to z = 2. On the other hand, the environmental quenching becomes efficient at z < 1 regardless of galaxy mass, and it serves as a main mechanism. for quenching star formation for lower mass galaxies. Our result is based on deep optical and near-infrared imaging data over 2800 arcmin(2), enabling us to negate cosmic variance and identify 46 galaxy cluster candidates with M similar to 10(14) M-circle dot. From M-* similar to 10(9.5) to 10(10.5) M-circle dot, the fraction of quiescent galaxies increases by a factor of similar to 10 over the entire redshift range, but the difference between cluster and field environment is negligible. Rapid evolution in the quiescent fraction is seen from z = 2 to z = 1.3 for massive galaxies, suggesting a build-up of massive quiescent galaxies at z > 1.3. For galaxies with M-circle dot < 10(10)M(circle dot) at z < 1.0, the quiescent fraction is found to be as much as a factor of 2 larger in clusters than in field, showing the importance of environmental quenching in low-mass galaxies at low redshift. Most high-mass galaxies are already quenched at z > 1, therefore environmental quenching does not play a significant role for them, although the efficiency of environmental quenching is nearly identical between high-and low-mass galaxies.</P>
CANDELS Sheds Light on the Environmental Quenching of Low-mass Galaxies
Guo, Yicheng,Bell, Eric F.,Lu, Yu,Koo, David C.,Faber, S. M.,Koekemoer, Anton M.,Kurczynski, Peter,Lee, Seong-Kook,Papovich, Casey,Chen, Zhu,Dekel, Avishai,Ferguson, Henry C.,Fontana, Adriano,Giavalis American Astronomical Society 2017 ASTROPHYSICAL JOURNAL LETTERS - Vol.841 No.2
<P>We investigate the environmental quenching of galaxies, especially those with stellar masses (M-*) < 10(9.5) Me-circle dot, beyond the local universe. Essentially all local low-mass quenched galaxies (QGs) are believed to live close to massive central galaxies, which is a demonstration of environmental quenching. We use CANDELS data to test whether or not such a dwarf QG-massive central galaxy connection exists beyond the local universe. For this purpose, we only need a statistically representative, rather than complete, sample of low-mass galaxies, which enables our study to z greater than or similar to 1.5. For each low-mass galaxy, we measure the projected distance (d(proj)) to its nearest massive neighbor (M-* > 10(10.5) M-circle dot) within a redshift range. At a given z and M-*, the environmental quenching effect is considered to be observed if the d(proj) distribution of QGs (d(proj)(Q)) is significantly skewed toward lower values than that of star-forming galaxies (d(proj)(SF)). For galaxies with 10(8) M-circle dot < M-* < 10(10) M-circle dot, such a difference between d(proj)(Q) and d(proj)(SF) is detected up to z similar to 1. Also, about 10% of the quenched galaxies in our sample are located between two and four virial radii (R-Vir) of the massive halos. The median projected distance from low-mass QGs to their massive neighbors, d(proj)(Q)/R-Vir, decreases with satellite M-* at M-* less than or similar to 10(9.5) M-circle dot, but increases with satellite M-* at M-* greater than or similar to 10(9.5) M-circle dot. This trend suggests a smooth, if any, transition of the quenching timescale around M-* similar to 10(9.5) M-circle dot at 0.5 < z < 1.0.</P>
Finner, Kyle,Jee, M. James,Golovich, Nathan,Wittman, David,Dawson, William,Gruen, Daniel,Koekemoer, Anton M.,Lemaux, Brian C.,Seitz, Stella American Astronomical Society 2017 The Astrophysical journal Vol.851 No.1
<P>The second most significant detection of the Planck Sunyaev-Zel'dovich survey, PLCK G287.0+32.9 (z = 0.385), boasts two similarly bright radio relics and a radio halo. One radio relic is located similar to 400 kpc NW of the X-ray peak and the other similar to 2.8 Mpc to the SE. This large difference suggests that a complex merging scenario is required. A key missing puzzle for the merging scenario reconstruction is the underlying dark matter distribution in high resolution. We present a joint Subaru Telescope and Hubble Space Telescope weak-lensing analysis of the cluster. Our analysis shows that the mass distribution features four significant substructures. Of the substructures, a primary cluster of mass M-200c = 1.59(-0.22)(+0.25) x 10(15) h(70)(-1) M-circle dot dominates the weak-lensing signal. This cluster is likely to be undergoing a merger with one (or more) subcluster whose mass is approximately a factor of 10 lower. One candidate is the subcluster of mass M-200c = 1.16(-0.13)(+0.15) x 10(14) h(70)(-1) M-circle dot located similar to 400 kpc to the SE. The location of this subcluster suggests that its interaction with the primary cluster could be the source of the NW radio relic. Another subcluster is detected similar to 2 Mpc to the SE of the X-ray peak with mass M-200c =1.68(-0.20)(+0.22) x 10(14) h(70)(-1) M-circle dot. This SE subcluster is in the vicinity of the SE radio relic and may have created the SE radio relic during a past merger with the primary cluster. The fourth subcluster, M-200c = 1.87(-0.22)(+0.24) x 10(14) h(70)(-1) M-circle dot, is NW of the X-ray peak and beyond the NW radio relic.</P>
EVOLUTION OF INTRINSIC SCATTER IN THE SFR-STELLAR MASS CORRELATION AT 0.5 < <i>z</i> < 3
Kurczynski, Peter,Gawiser, Eric,Acquaviva, Viviana,Bell, Eric F.,Dekel, Avishai,de Mello, Duilia F.,Ferguson, Henry C.,Gardner, Jonathan P.,Grogin, Norman A.,Guo, Yicheng,Hopkins, Philip F.,Koekemoer, American Astronomical Society 2016 ASTROPHYSICAL JOURNAL LETTERS - Vol.820 No.1
<P>We present estimates of intrinsic scatter in the star formation rate (SFR)-stellar mass (M-*) correlation in the redshift range 0.5 < z < 3.0 and in the mass range 10(7) < M-* < 10(11)M(circle dot). We utilize photometry in the Hubble Ultradeep Field (HUDF12) and Ultraviolet Ultra Deep Field (UVUDF) campaigns and CANDELS/GOODS-S and estimate SFR, M-* from broadband spectral energy distributions and the best-available redshifts. The maximum depth of the UDF photometry (F160W 29.9 AB, 5 sigma depth) probes the SFR-M-* correlation down to M-* similar to 10(7)M(circle dot), a factor of 10-100x lower in M-* than previous studies, and comparable to dwarf galaxies in the local universe. We find the slope of the SFR-M-* relationship to be near unity at all redshifts and the normalization to decrease with cosmic time. We find a moderate increase in intrinsic scatter with cosmic time from 0.2 to 0.4 dex across the epoch of peak cosmic star formation. None of our redshift bins show a statistically significant increase in intrinsic scatter at low mass. However, it remains possible that intrinsic scatter increases at low mass on timescales shorter than similar to 100 Myr. Our results are consistent with a picture of gradual and self-similar assembly of galaxies across more than three orders of magnitude in stellar mass from as low as 10(7)M(circle dot).</P>
DISCOVERY OF A STRONG LENSING GALAXY EMBEDDED IN A CLUSTER AT z = 1.62
WONG, KENNETH C.,TRAN, KIM-VY H.,SUYU, SHERRY H.,MOMCHEVA, IVELINA G.,BRAMMER, GABRIEL B.,BRODWIN, MARK,GONZALEZ, ANTHONY H.,HALKOLA, ALEKSI,KACPRZAK, GLENN G.,KOEKEMOER, ANTON M.,PAPOVICH, CASEY J.,R The Korean Astronomical Society 2015 天文學論叢 Vol.30 No.2
We identify a strong lensing galaxy in the cluster IRC 0218 that is spectroscopically confirmed to be at z = 1.62, making it the highest-redshift strong lens galaxy known. The lens is one of the two brightest cluster galaxies and lenses a background source galaxy into an arc and a counterimage. With Hubble Space Telescope (HST) grism and Keck/LRIS spectroscopy, we measure the source redshift to be $z_S=2.26$. Using HST imaging, we model the lens mass distribution with an elliptical power-law profile and account for the effects of the cluster halo and nearby galaxies. The Einstein radius is $^{\theta}E=0.38^{+0.02{\prime}{\prime}}_{-0.01}$ ($3.2^{+0.2}_{-0.1}kpc$) and the total enclosed mass is $M_{tot}(<^{\theta}_E)=1.8^{+0.2}_{-0.1}{\times}10^{11}M_{\odot}$. We estimate that the cluster environment contributes ~ 10% of this total mass. Assuming a Chabrier IMF, the dark matter fraction within $^{\theta}E$ is $f^{Chab}_{DM}=0.3^{+0.1}_{-0.3}$, while a Salpeter IMF is marginally inconsistent with the enclosed mass ($f^{Salp}_{DM}=-0.3^{+0.2}_{-0.5}$).