scholarly journals Photometric redshifts for galaxies in the Subaru Hyper Suprime-Cam and unWISE and a catalogue of identified clusters of galaxies

2020 ◽  
Vol 500 (1) ◽  
pp. 1003-1017
Author(s):  
Z L Wen ◽  
J L Han
Keyword(s):  
High Redshift ◽  
Large Data ◽  
Wide Field ◽  
Clusters Of Galaxies ◽  
Photometric Redshifts ◽  
Data Set ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Brightest Cluster Galaxies ◽  
Strategic Program

ABSTRACT We first present a catalogue of photometric redshifts for 14.68 million galaxies derived from the 7-band photometric data of Hyper Suprime-Cam Subaru Strategic Program and the Wide-field Infrared Survey Explorer using the nearest-neighbour algorithm. The redshift uncertainty is about 0.024 for galaxies of z ≤ 0.7, and steadily increases with redshift to about 0.11 at z ∼ 2. From such a large data set, we identify 21 661 clusters of galaxies, among which 5537 clusters have redshifts z > 1 and 642 clusters have z > 1.5, significantly enlarging the high redshift sample of galaxy clusters. Cluster richness and mass are estimated, and these clusters have an equivalent mass of M500 ≥ 0.7 × 1014 M⊙. We find that the stellar mass of the brightest cluster galaxies (BCGs) in each richness bin does not significantly evolve with redshift. The fraction of star-forming BCGs increases with redshift, but does not depend on cluster mass.

scholarly journals The Hyper Suprime-Cam SSP transient survey in COSMOS: Overview

2019 ◽  
Vol 71 (4) ◽  
Author(s):  
Naoki Yasuda ◽  
Masaomi Tanaka ◽  
Nozomu Tominaga ◽  
Ji-an Jiang ◽  
Takashi J Moriya ◽  
...  
Keyword(s):  
Light Curve ◽  
Deep Layer ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Variable Stars ◽  
Photometric Redshifts ◽  
Data Set ◽  
Type Ia ◽  
Strategic Program ◽  
Ia Supernovae

Abstract We present an overview of a deep transient survey of the COSMOS field with the Subaru Hyper Suprime-Cam (HSC). The survey was performed for the 1.77 deg2 ultra-deep layer and 5.78 deg2 deep layer in the Subaru Strategic Program over six- and four-month periods from 2016 to 2017, respectively. The ultra-deep layer reaches a median depth per epoch of 26.4, 26.3, 26.0, 25.6, and 24.6 mag in g, r, i, z, and y bands, respectively; the deep layer is ∼0.6 mag shallower. In total, 1824 supernova candidates were identified. Based on light-curve fitting and derived light-curve shape parameter, we classified 433 objects as Type Ia supernovae (SNe); among these candidates, 129 objects have spectroscopic or COSMOS2015 photometric redshifts and 58 objects are located at z > 1. Our unique data set doubles the number of Type Ia SNe at z > 1 and enables various time-domain analyses of Type II SNe, high-redshift superluminous SNe, variable stars, and active galactic nuclei.

scholarly journals Passive spirals and shock influenced star formation in the merging cluster A3376

2020 ◽  
Vol 496 (1) ◽  
pp. 442-455 ◽  
Author(s):  
Kshitija Kelkar ◽  
K S Dwarakanath ◽  
Bianca M Poggianti ◽  
Alessia Moretti ◽  
Rogério Monteiro-Oliveira ◽  
...  
Keyword(s):  
Star Formation ◽  
Rapid Quenching ◽  
Wide Field ◽  
Cluster Galaxies ◽  
Star Forming ◽  
M 10 ◽  
Brightest Cluster Galaxies ◽  
Central Regions ◽  
Cluster Environment ◽  
Low Mass

ABSTRACT We present a detailed analysis of star formation properties of galaxies in a nearby (z ∼ 0.046) young (∼0.6 Gyr) post-merger cluster system A3376, with a moderate merger shock front (vs ∼1630 km s−1; $\mathcal {M}$ ∼ 2) observed as symmetric radio relics. Exploiting the spectroscopic data from the wide-field OmegaWINGS survey and the associated photometric information, our investigations reveal the plausible effects of the dynamic post-merger environment differing from the high-density cluster environment experienced prior to the merging activity. The remnants of the pre-merger relaxed cluster environment are realized through the existence of passive spiral galaxies located in the central regions of the cluster between the two brightest cluster galaxies. We discover A3376 to contain a population of massive (log (M*/M⊙) > 10) blue regular star-forming spirals in regions of maximum merger shock influence but exhibiting star formation rates similar to those in relaxed clusters at similar epoch. We further discover low-mass (log (M*/M⊙) ≤ 10) late-type blue post-starburst galaxies which could either be formed as a result of rapid quenching of low-mass spirals following the shock-induced star formation or due to the intense surge in the intracluster medium pressures at the beginning of the merger. With the possibility of the merger shock affecting high- and low-mass spirals differently, our results bridge the seemingly contradictory results observed in known merging cluster systems so far and establish that different environmental effects are at play right from pre- to post-merger stages.

The light side of proto-cluster galaxies at z ∼ 4

2020 ◽  
Vol 15 (S359) ◽  
pp. 126-130
Author(s):  
Kei Ito
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Cluster Galaxies ◽  
Active Structure ◽  
Brightest Cluster Galaxies ◽  
Sky Survey ◽  
Strategic Program ◽  
Light Side ◽  
Star Formation Histories ◽  
Early Galaxy

AbstractOverdense regions at high redshift, which are often called “protoclusters”, are thought to be a place where the early active structure formations are in progress. Thanks to the wide and deep-sky survey of Hyper Suprime-Cam Subaru Strategic Program, we have selected 179 protocluster candidates at z ˜ 4, enabling us to statistically discuss high-z overdense regions. I report results of the HSC-SSP protocluster project, focusing on a couple of results on the bright-end of protocluster galaxies. We identify the UV-brightest galaxies, which are likely progenitors of Brightest Cluster Galaxies. We find that these are dustier and larger than field galaxies. This suggests that galaxies in protoclusters have experienced different star formation histories at z ˜ 4. Also, the UV luminosity function of galaxies in protoclusters (PC UVLF) has a significant excess on the bright-end from field UVLF. The PC UVLF suggests that protoclusters contribute ˜ 5 – 16% of the total cosmic SFRD at z ˜ 4. The result implies that early galaxy formation occurs in protoclusters.

scholarly journals Clocking the formation of today’s largest galaxies: wide field integral spectroscopy of brightest cluster galaxies and their surroundings

2019 ◽  
Vol 491 (2) ◽  
pp. 2617-2638 ◽  
Author(s):  
Louise O V Edwards ◽  
Matthew Salinas ◽  
Steffanie Stanley ◽  
Priscilla E Holguin West ◽  
Isabella Trierweiler ◽  
...  
Keyword(s):  
Velocity Dispersion ◽  
Minor Component ◽  
High Signal ◽  
Wide Field ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
The Galaxy ◽  
Formation And Evolution ◽  
Intracluster Light ◽  
A Minor

ABSTRACT The formation and evolution of local brightest cluster galaxies (BCGs) is investigated by determining the stellar populations and dynamics from the galaxy core, through the outskirts and into the intracluster light (ICL). Integral spectroscopy of 23 BCGs observed out to $4\, r_{e}$ is collected and high signal-to-noise regions are identified. Stellar population synthesis codes are used to determine the age, metallicity, velocity, and velocity dispersion of stars within each region. The ICL spectra are best modelled with populations that are younger and less metal-rich than those of the BCG cores. The average BCG core age of the sample is $\rm 13.3\pm 2.8\, Gyr$ and the average metallicity is $\rm [Fe/H] = 0.30\pm 0.09$, whereas for the ICL the average age is $\rm 9.2\pm 3.5\, Gyr$ and the average metallicity is $\rm [Fe/H] = 0.18\pm 0.16$. The velocity dispersion profile is seen to be rising or flat in most of the sample (17/23), and those with rising values reach the value of the host cluster’s velocity dispersion in several cases. The most extended BCGs are closest to the peak of the cluster’s X-ray luminosity. The results are consistent with the idea that the BCG cores and inner regions formed quickly and long ago, with the outer regions and ICL forming more recently, and continuing to assemble through minor merging. Any recent star formation in the BCGs is a minor component, and is associated with the cluster cool core status.

scholarly journals Molecular gas in distant brightest cluster galaxies

2020 ◽  
Vol 635 ◽  
pp. A32 ◽  
Author(s):  
G. Castignani ◽  
F. Combes ◽  
P. Salomé ◽  
J. Freundlich
Keyword(s):  
Star Formation ◽  
Stellar Mass ◽  
Star Formation History ◽  
Gas Content ◽  
Molecular Gas ◽  
Distant Cluster ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Distant Star ◽  
Brightest Cluster Galaxies

The mechanisms governing the stellar mass assembly and star formation history of brightest cluster galaxies (BCGs) are still being debated. By means of new and archival molecular gas observations we investigate the role of dense megaparsec-scale environments in regulating the fueling of star formation in distant BCGs, through cosmic time. We observed in CO with the IRAM 30 m telescope two star-forming BCGs belonging to SpARCS clusters, namely, 3C 244.1 (z = 0.4) and SDSS J161112.65+550823.5 (z = 0.9), and compared their molecular gas and star formation properties with those of a compilation of ∼100 distant cluster galaxies from the literature, including nine additional distant BCGs at z  ∼  0.4 − 3.5. We set robust upper limits of MH2 <  1.0 × 1010 M⊙ and < 2.8 × 1010 M⊙ to their molecular gas content, respectively, and to the ratio of molecular gas to stellar mass M(H2)/M⋆ ≲ 0.2 and depletion time τdep ≲ 40 Myr of the two targeted BCGs. They are thus among the distant cluster galaxies with the lowest gas fractions and shortest depletion times. The majority (64%±15% and 73%±18%) of the 11 BCGs with observations in CO have lower M(H2)/M⋆ values and τdep, respectively, than those estimated for main sequence galaxies. Statistical analysis also tentatively suggests that the values of M(H2)/M⋆ and τdep for the 11 BCGs deviates, with a significance of ∼2σ, from those of the comparison sample of cluster galaxies. A morphological analysis for a subsample of seven BCGs with archival HST observations reveals that 71%±17% of the BCGs are compact or show star-forming components or substructures. Our results suggest a scenario where distant star-forming BCGs assemble a significant fraction ∼16% of their stellar mass on the relatively short timescale ∼τdep, while environmental mechanisms might prevent the replenishment of gas feeding the star formation. We speculate that compact components also favor the rapid exhaustion of molecular gas and ultimately help to quench the BCGs. Distant star-forming BCGs are excellent targets for ALMA and for next-generation telescopes such as the James Webb Space Telescope.

scholarly journals STAR-FORMING BRIGHTEST CLUSTER GALAXIES AT 0.25

2016 ◽  
Vol 817 (2) ◽  
pp. 86 ◽  
Author(s):  
M. McDonald ◽  
B. Stalder ◽  
M. Bayliss ◽  
S. W. Allen ◽  
D. E. Applegate ◽  
...  
Keyword(s):  
Cluster Galaxies ◽  
Star Forming ◽  
Fuel Supply ◽  
Brightest Cluster Galaxies

scholarly journals Large scale profiles of galaxies at z=0-2 studied by stacking the HSC SSP survey data

2016 ◽  
Vol 11 (S321) ◽  
pp. 318-320
Author(s):  
Mariko Kubo ◽  
Masami Ouchi ◽  
Takatoshi Shibuya
Keyword(s):  
Survey Data ◽  
Surface Brightness ◽  
Large Scale ◽  
High Redshift ◽  
Photometric Redshifts ◽  
Early Formation ◽  
The Galaxy ◽  
Strategic Program ◽  
Galaxy Populations ◽  
Using Data

AbstractWe are carrying out the study of the evolution of radial surface brightness profiles of galaxies from z = 0 to 2 by stacking analysis using data corrected by the Hyper Suprime-Cam (HSC) Subaru Strategic Program (SSP). This will allow us to constrain the large scale average profiles of various galaxy populations at high redshift. From the stacking analysis of galaxies selected based on their photometric redshifts, we successfully detected the outer components of galaxies at z > 1 extending to at least ~80 kpc, which imply an early formation for the galaxy outskirts.

scholarly journals HST/WFC3 Grism Observations of z ∼ 1 Clusters: Evidence for Rapid Outside-in Environmental Quenching from Spatially Resolved Hα Maps

2021 ◽  
Vol 923 (2) ◽  
pp. 222
Author(s):  
Jasleen Matharu ◽  
Adam Muzzin ◽  
Gabriel B. Brammer ◽  
Erica J. Nelson ◽  
Matthew W. Auger ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Stellar Mass ◽  
Wide Field ◽  
Cluster Galaxy ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Spatially Resolved ◽  
Field Environment ◽  
Ram Pressure ◽  
Quenching Process

Abstract We present and publicly release (www.gclasshst.com) the first spatially resolved Hα maps of star-forming cluster galaxies at z ∼ 1, made possible with the Wide Field Camera 3 (WFC3) G141 grism on the Hubble Space Telescope (HST). Using a similar but updated method to 3D-HST in the field environment, we stack the Hα maps in bins of stellar mass, measure the half-light radius of the Hα distribution, and compare it to the stellar continuum. The ratio of the Hα to stellar continuum half-light radius, R [ H α / C ] = R eff , H α R eff , Cont , is smaller in the clusters by (6 ± 9)%, but statistically consistent within 1σ uncertainties. A negligible difference in R[Hα/C] with environment is surprising, given the higher quenched fractions in the clusters relative to the field. We postulate that the combination of high quenched fractions and no change in R[Hα/C] with environment can be reconciled if environmental quenching proceeds rapidly. We investigate this hypothesis by performing similar analysis on the spectroscopically confirmed, recently quenched cluster galaxies. 87% have Hα detections, with star formation rates 8 ± 1 times lower than star-forming cluster galaxies of similar stellar mass. Importantly, these galaxies have an R[Hα/C] that is (81 ± 8)% smaller than coeval star-forming field galaxies at fixed stellar mass. This suggests the environmental quenching process occurred outside-in. We conclude that disk truncation due to ram pressure stripping is occurring in cluster galaxies at z ∼ 1, but more rapidly and/or efficiently than in z ≲ 0.5 clusters, such that the effects on R[Hα/C] become observable just after the cluster galaxy has recently quenched.

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