scholarly journals The double galaxy cluster Abell 2465 – II. Star formation in the cluster

2014 ◽  
Vol 447 (2) ◽  
pp. 1126-1140 ◽  
Author(s):  
Gary A. Wegner ◽  
Devin S. Chu ◽  
Ho Seong Hwang
2020 ◽  
Vol 15 (S359) ◽  
pp. 170-172
Author(s):  
Rosemary T. Coogan ◽  
E. Daddi ◽  
R. Gobat ◽  
M. T. Sargent

AbstractThis work focuses on understanding the formation of the first massive, passive galaxies in clusters, as a first step to the development of environmental trends seen at low redshift. Cl J1449 + 0856 is an excellent case to study this - a galaxy cluster at redshift z = 1.99 that already shows evidence of a virialised atmosphere. Here we highlight two recent results: the discovery of merger-driven star formation and highly-excited molecular gas in galaxies at the core of Cl J1449, along with the lowest-mass Sunyaev-Zel’dovich detection to date.


2018 ◽  
Vol 620 ◽  
pp. A60 ◽  
Author(s):  
R. Cañameras ◽  
N. P. H. Nesvadba ◽  
M. Limousin ◽  
H. Dole ◽  
R. Kneissl ◽  
...  

We report the discovery of a molecular wind signature from a massive intensely star-forming clump of a few 109 M⊙, in the strongly gravitationally lensed submillimeter galaxy “the Emerald” (PLCK_G165.7+49.0) at z = 2.236. The Emerald is amongst the brightest high-redshift galaxies on the submillimeter sky, and was initially discovered with the Planck satellite. The system contains two magnificient structures with projected lengths of 28.5″ and 21″ formed by multiple, near-infrared arcs, falling behind a massive galaxy cluster at z = 0.35, as well as an adjacent filament that has so far escaped discovery in other wavebands. We used HST/WFC3 and CFHT optical and near-infrared imaging together with IRAM and SMA interferometry of the CO(4–3) line and 850 μm dust emission to characterize the foreground lensing mass distribution, construct a lens model with LENSTOOL, and calculate gravitational magnification factors between 20 and 50 in most of the source. The majority of the star formation takes place within two massive star-forming clumps which are marginally gravitationally bound and embedded in a 9 × 1010 M⊙, fragmented disk with 20% gas fraction. The stellar continuum morphology is much smoother and also well resolved perpendicular to the magnification axis. One of the clumps shows a pronounced blue wing in the CO(4–3) line profile, which we interpret as a wind signature. The mass outflow rates are high enough for us to suspect that the clump might become unbound within a few tens of Myr, unless the outflowing gas can be replenished by gas accretion from the surrounding disk. The velocity offset of –200 km s−1 is above the escape velocity of the clump, but not that of the galaxy overall, suggesting that much of this material might ultimately rain back onto the galaxy and contribute to fueling subsequent star formation.


2016 ◽  
Vol 465 (3) ◽  
pp. 2916-2935 ◽  
Author(s):  
Andra Stroe ◽  
David Sobral ◽  
Ana Paulino-Afonso ◽  
Lara Alegre ◽  
João Calhau ◽  
...  

2012 ◽  
Vol 756 (2) ◽  
pp. L28 ◽  
Author(s):  
Yara L. Jaffé ◽  
Bianca M. Poggianti ◽  
Marc A. W. Verheijen ◽  
Boris Z. Deshev ◽  
Jacqueline H. van Gorkom

2019 ◽  
Vol 487 (1) ◽  
pp. 1210-1217 ◽  
Author(s):  
Ariane Trudeau ◽  
Tracy Webb ◽  
Julie Hlavacek-Larrondo ◽  
Allison Noble ◽  
Marie-Lou Gendron-Marsolais ◽  
...  

ABSTRACT We present deep, multiwavelength radio observations of SpARCS104922.6 + 564032.5, a z = 1.71 galaxy cluster with a starbursting core. Observations were made with the Karl G. Jansky Very Large Array (JVLA) in three bands: 1–2 GHz, 4–8 GHz, and 8–12 GHz. We detect a radio source coincident with the brightest cluster galaxy (BCG) that has a spectral index of α = 0.44 ± 0.29 and is indicative of emission from an active galactic nucleus. The radio luminosity is consistent with the average luminosity of the lower redshift BCG sample, but the flux densities are 6σ below the predicted values of the star-forming spectral energy distribution based on far infrared data. Our new fit fails to simultaneously describe the far infrared and radio fluxes. This, coupled with the fact that no other bright source is detected in the vicinity of the BCG implies that the star formation region, traced by the infrared emission, is extended or clumpy and not located directly within the BCG. Thus, we suggest that the star-forming core might not be driven by a single major wet merger, but rather by several smaller galaxies stripped of their gas or by a displaced cooling flow, although more data are needed to confirm any of those scenarios.


1996 ◽  
Vol 171 ◽  
pp. 474-475
Author(s):  
Rogier A. Windhorst ◽  
Sam M. Pascarelle ◽  
William C. Keel

We present a 67-orbit HST/WFPC2 exposure on the weak radio galaxy 53W002 at z=2.390 and its surrounding cluster. Color Plate 1 shows 12 orbits in IF814W & VF606W, and 24 in BF450W. Potential cluster members were identified through 15 orbits in F410M, optimized for narrow-band searches for compact Lyα objects at z≃2.4 (P96), and confirmed through spectroscopy (W91, P96); 16 candidates were found with significant narrow-band emission in F410M: 4 out of 5 had a confirming MMT spectroscopic redshift at z≃2.40 (P96). All are located within 60″ from 53W002, or ∼ 0.24h–1100 Mpc (qo=0.5) at z ≃2.4, the physical scale of a group or small galaxy cluster. One object contains a weak (variable) AGN, another is a merger with two companions. Their underlying young stellar population is very compact, with rh.l. ≃0.2″ (≃ 0.8h–1100 kpc), and considerably fainter than the L∗-value at z∼2.4, implying sub-galactic sized objects. These results may explain why ground-based Lya searches for PG's have been largely unsuccessful. The narrow-line galaxy 53W002 was imaged in the PC at ∼0.07″ FWHM (WK95, see also W94). Its AGN component is ≤ 20±4% of the total continuum, surrounded by an extended r1/4-envelope with rh.l. ≃1.1″ (4.3 kpc), and has an SED of ∼0.3 Gyr in the center to ∼0.5-1.0 Gyr at ∼4 kpc. A one-sided cloud is seen ∼1.8 kpc West, ∼0.3 mag bluer than the SED, aligned with the radio source and its Ly-α cloud, presumably weak scattered AGN light, and/or jet-induced star-formation.


2015 ◽  
Vol 15 (11) ◽  
pp. 1773-1783 ◽  
Author(s):  
Peng-Fei Yan ◽  
Feng Li ◽  
Qi-Rong Yuan

2016 ◽  
Vol 825 (2) ◽  
pp. 108 ◽  
Author(s):  
T. F. Laganá ◽  
M. P. Ulmer ◽  
L. P. Martins ◽  
E. da Cunha

2019 ◽  
Vol 490 (1) ◽  
pp. 135-155 ◽  
Author(s):  
Seong-Kook Lee ◽  
Myungshin Im ◽  
Minhee Hyun ◽  
Bomi Park ◽  
Jae-Woo Kim ◽  
...  

ABSTRACT High-redshift galaxy clusters, unlike local counterparts, show diverse star formation activities. However, it is still unclear what keeps some of the high-redshift clusters active in star formation. To address this issue, we performed a multiobject spectroscopic observation of 226 high-redshift (0.8 < z < 1.3) galaxies in galaxy cluster candidates and the areas surrounding them. Our spectroscopic observation reveals six to eight clusters/groups at z ∼ 0.9 and z ∼ 1.3. The redshift measurements demonstrate the reliability of our photometric redshift measurements, which in turn gives credibility for using photometric redshift members for the analysis of large-scale structures (LSSs). Our investigation of the large-scale environment (∼10 Mpc) surrounding each galaxy cluster reveals LSSs – structures up to ∼10 Mpc scale – around many of, but not all, the confirmed overdensities and the cluster candidates. We investigate the correlation between quiescent galaxy fraction of galaxy overdensities and their surrounding LSSs, with a larger sample of ∼20 overdensities including photometrically selected overdensities at 0.6 < z < 0.9. Interestingly, galaxy overdensities embedded within these extended LSSs show a lower fraction of quiescent galaxies ($\sim 20{{\ \rm per\ cent}}$) than isolated ones at similar redshifts (with a quiescent galaxy fraction of $\sim 50 {{\ \rm per\ cent}}$). Furthermore, we find a possible indication that clusters/groups with a high quiescent galaxy fraction are more centrally concentrated. Based on these results, we suggest that LSSs are the main reservoirs of gas and star-forming galaxies to keep galaxy clusters fresh and extended in size at z ∼ 1.


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