scholarly journals Spitzer Planck Herschel Infrared Cluster (SPHerIC) survey: Candidate galaxy clusters at 1.3 < z < 3 selected by high star-formation rate

2018 ◽  
Vol 620 ◽  
pp. A198 ◽  
Author(s):  
C. Martinache ◽  
A. Rettura ◽  
H. Dole ◽  
M. Lehnert ◽  
B. Frye ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Formation Rate ◽  
Physical Processes ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Efficient Detection ◽  
Star Formation In Galaxies ◽  
The Individual ◽  
Massive Clusters

There is a lack of large samples of spectroscopically confirmed clusters and protoclusters at high redshifts, z > 1.5. Discovering and characterizing distant (proto-)clusters is important for yielding insights into the formation of large-scale structure and on the physical processes responsible for regulating star-formation in galaxies in dense environments. The Spitzer Planck Herschel Infrared Cluster (SPHerIC) survey was initiated to identify these characteristically faint and dust-reddened sources during the epoch of their early assembly. We present Spitzer/IRAC observations of 82 galaxy (proto-)cluster candidates at 1.3 < zp < 3.0 that were vetted in a two step process: (1) using Planck to select by color those sources with the highest star-formation rates, and (2) using Herschel at higher resolution to separate out the individual red sources. The addition of the Spitzer data enables efficient detection of the central and massive brightest red cluster galaxies (BRCGs). We find that BRCGs are associated with highly significant, extended and crowded regions of IRAC sources which are more overdense than the field. This result corroborates our hypothesis that BRCGs within the Planck–Herschel sources trace some of the densest and actively star-forming proto-clusters in the early Universe. On the basis of a richness-mass proxy relation, we obtain an estimate of their mean masses which suggests our sample consists of some of the most massive clusters at z ≈ 2 and are the likely progenitors of the most massive clusters observed today.

scholarly journals A MUSE inquiry into the physical processes taking place within the Abell 2667 Brightest Cluster Galaxy

2019 ◽  
Vol 15 (S341) ◽  
pp. 83-87
Author(s):  
E. Iani ◽  
G. Rodighiero ◽  
J. Fritz ◽  
G. Cresci ◽  
C. Mancini ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Resolving Power ◽  
Mass Star ◽  
Physical Processes ◽  
Cluster Galaxy ◽  
Cluster Galaxies ◽  
Star Forming ◽  
Cold Star ◽  
Field Unit

AbstractBrightest cluster galaxies (BCGs) residing in cool-core clusters are known to be the stage of intricate baryon cycle phenomena (e.g. gas inflows, AGN outflows, star formation feedback). The scenarios describing the observed properties of these galaxies are still controversial, suffering from limitations due to the spatial resolving power of the instruments, specifically for galaxies beyond the Local Universe. However, the dramatic improvements introduced by the integral-field unit instruments (e.g. MUSE) could shed light on the physical processes driving the evolution of these galaxies. We present an extensive analysis of the stellar and gas properties (i.e. kinematics, stellar mass, star formation rate) of the radio-loud BCG sitting at the centre of the X-ray luminous cool-core cluster Abell 2667 (z = 0.23), based on MUSE data. Our results indicate that the BCG is a massive elliptical, hosting an AGN that is possibly undergoing accretion of cold star-forming clouds of ICM or galactic cannibalism.

scholarly journals Persistence of the colour–density relation and efficient environmental quenching to z ∼ 1.4

2019 ◽  
Vol 490 (1) ◽  
pp. 1231-1254 ◽  
Author(s):  
B C Lemaux ◽  
A R Tomczak ◽  
L M Lubin ◽  
R R Gal ◽  
L Shen ◽  
...  
Keyword(s):  
Star Formation ◽  
Time Scales ◽  
Large Scale ◽  
Formation Rate ◽  
Cosmic Time ◽  
Stellar Mass ◽  
Cluster Galaxies ◽  
Quenching Efficiency ◽  
Density Relation ◽  
Galaxy Populations

ABSTRACT Using ∼5000 spectroscopically confirmed galaxies drawn from the Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey we investigate the relationship between colour and galaxy density for galaxy populations of various stellar masses in the redshift range 0.55 ≤ z ≤ 1.4. The fraction of galaxies with colours consistent with no ongoing star formation (fq) is broadly observed to increase with increasing stellar mass, increasing galaxy density, and decreasing redshift, with clear differences observed in fq between field and group/cluster galaxies at the highest redshifts studied. We use a semi-empirical model to generate a suite of mock group/cluster galaxies unaffected by environmentally specific processes and compare these galaxies at fixed stellar mass and redshift to observed populations to constrain the efficiency of environmentally driven quenching (Ψconvert). High-density environments from 0.55 ≤ z ≤ 1.4 appear capable of efficiently quenching galaxies with $\log (\mathcal {M}_{\ast }/\mathcal {M}_{\odot })\gt 10.45$. Lower stellar mass galaxies also appear efficiently quenched at the lowest redshifts studied here, but this quenching efficiency is seen to drop precipitously with increasing redshift. Quenching efficiencies, combined with simulated group/cluster accretion histories and results on the star formation rate-density relation from a companion ORELSE study, are used to constrain the average time from group/cluster accretion to quiescence and the elapsed time between accretion and the inception of the quenching event. These time-scales were constrained to be 〈tconvert〉 = 2.4 ± 0.3 and 〈tdelay〉 = 1.3 ± 0.4 Gyr, respectively, for galaxies with $\log (\mathcal {M}_{\ast }/\mathcal {M}_{\odot })\gt 10.45$ and 〈tconvert〉 = 3.3 ± 0.3 and 〈tdelay〉 = 2.2 ± 0.4 Gyr for lower stellar mass galaxies. These quenching efficiencies and associated time-scales are used to rule out certain environmental mechanisms as being the primary processes responsible for transforming the star formation properties of galaxies over this 4 Gyr window in cosmic time.

scholarly journals Slow-then-rapid quenching as traced by tentative evidence for enhanced metallicities of cluster galaxies at z ∼ 0.2 in the slow quenching phase

2019 ◽  
Vol 621 ◽  
pp. A131 ◽  
Author(s):  
C. Maier ◽  
B. L. Ziegler ◽  
C. P. Haines ◽  
G. P. Smith
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Rapid Quenching ◽  
Cluster Center ◽  
Cluster Galaxy ◽  
Local Cluster ◽  
Cluster Galaxies ◽  
Star Forming ◽  
The Galaxy ◽  
Tentative Evidence

Aims. As large-scale structures in the Universe develop with time, environmental effects become more and more important as a star formation quenching mechanism. Since the effects of environmental quenching are more pronounced in denser structures that form at later times, we seek to constrain environmental quenching processes using cluster galaxies at z <  0.3. Methods. We explored seven clusters from the Local Cluster Substructure Survey (LoCuSS) at 0.15 <  z <  0.26 with spectra of 1965 cluster members in a mass-complete sample from the ACReS (Arizona Cluster Redshift Survey) Hectospec survey covering a region that corresponds to about three virial radii for each cluster. We measured fluxes of [O II] λ 3727, Hβ, [O III] λ 5007, Hα, and [N II] λ 6584 emission lines of cluster members, enabling us to unambiguously derive O/H gas metallicities. We also measured star formation rates (SFRs) from extinction-corrected Hα fluxes. We compared our cluster galaxy sample with a field sample of 705 galaxies at similar redshifts observed with Hectospec as part of the same survey. Results. We find that star-forming cluster and field galaxies show similar median specific SFRs in a given mass bin of 1 − 3.2 × 1010 M⊙ and 3.2 − 10 × 1010 M⊙, respectively. But their O/H values are displaced, in the lower mass bin, to higher values (significance 2.4σ) at projected radii of R <  R200 compared with galaxies at larger radii and in the field. The comparison with metallicity-SFR-mass model predictions with inflowing gas indicates a slow-quenching scenario in which strangulation is initiated when galaxies pass R ∼ R200 by stopping the inflow of gas. We find tentative evidence that the metallicities of cluster members inside R200 are thereby increasing, but their SFRs are hardly affected for a period of time because these galaxies consume available disk gas. We use the observed fraction of star-forming cluster galaxies as a function of clustercentric radius compared to predictions from the Millennium simulation to constrain quenching timescales to be 1−2 Gyr, which is defined as the time between the moment the galaxy passes R200 until complete quenching of star formation. This is consistent with a slow-then-rapid quenching scenario. Slow quenching (strangulation) starts when the gas inflow is stopped when the galaxy passes R200 with a phase in which cluster galaxies are still star forming, but they show elevated metallicities tracing the ongoing quenching. This phase lasts for 1−2 Gyr, and meanwhile the galaxies travel to denser inner regions of the cluster. This is followed by a “rapid” phase, i.e., a rapid complete quenching of star formation due to the increasing ram pressure toward the cluster center that can also strip the cold gas in massive galaxies.

scholarly journals Simulations of the star-forming molecular gas in an interacting M51-like galaxy

2020 ◽  
Vol 492 (2) ◽  
pp. 2973-2995 ◽  
Author(s):  
Robin G Tress ◽  
Rowan J Smith ◽  
Mattia C Sormani ◽  
Simon C O Glover ◽  
Ralf S Klessen ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Formation Rate ◽  
Three Dimensional ◽  
Molecular Gas ◽  
Secondary Importance ◽  
Star Forming ◽  
The Galaxy ◽  
Cold Star ◽  
Self Gravity

ABSTRACT We present here the first of a series of papers aimed at better understanding the evolution and properties of giant molecular clouds (GMCs) in a galactic context. We perform high-resolution, three-dimensional arepo simulations of an interacting galaxy inspired by the well-observed M51 galaxy. Our fiducial simulations include a non-equilibrium, time-dependent, chemical network that follows the evolution of atomic and molecular hydrogen as well as carbon and oxygen self-consistently. Our calculations also treat gas self-gravity and subsequent star formation (described by sink particles), and coupled supernova feedback. In the densest parts of the simulated interstellar medium (ISM), we reach sub-parsec resolution, granting us the ability to resolve individual GMCs and their formation and destruction self-consistently throughout the galaxy. In this initial work, we focus on the general properties of the ISM with a particular focus on the cold star-forming gas. We discuss the role of the interaction with the companion galaxy in generating cold molecular gas and controlling stellar birth. We find that while the interaction drives large-scale gas flows and induces spiral arms in the galaxy, it is of secondary importance in determining gas fractions in the different ISM phases and the overall star formation rate. The behaviour of the gas on small GMC scales instead is mostly controlled by the self-regulating property of the ISM driven by coupled feedback.

scholarly journals The EDGE-CALIFA survey: exploring the role of molecular gas on galaxy star formation quenching

2020 ◽  
Vol 644 ◽  
pp. A97
Author(s):  
D. Colombo ◽  
S. F. Sanchez ◽  
A. D. Bolatto ◽  
V. Kalinova ◽  
A. Weiß ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Large Scale ◽  
Formation Rate ◽  
Molecular Gas ◽  
Star Forming ◽  
Average Value ◽  
First Results ◽  
Gas Consumption ◽  
Formation Efficiency

Understanding how galaxies cease to form stars represents an outstanding challenge for galaxy evolution theories. This process of “star formation quenching” has been related to various causes, including active galactic nuclei activity, the influence of large-scale dynamics, and the environment in which galaxies live. In this paper, we present the first results from a follow-up of CALIFA survey galaxies with observations of molecular gas obtained with the APEX telescope. Together with the EDGE-CARMA observations, we collected 12CO observations that cover approximately one effective radius in 472 CALIFA galaxies. We observe that the deficit of galaxy star formation with respect to the star formation main sequence (SFMS) increases with the absence of molecular gas and with a reduced efficiency of conversion of molecular gas into stars, which is in line with the results of other integrated studies. However, by dividing the sample into galaxies dominated by star formation and galaxies quenched in their centres (as indicated by the average value of the Hα equivalent width), we find that this deficit increases sharply once a certain level of gas consumption is reached, indicating that different mechanisms drive separation from the SFMS in star-forming and quenched galaxies. Our results indicate that differences in the amount of molecular gas at a fixed stellar mass are the primary drivers for the dispersion in the SFMS, and the most likely explanation for the start of star formation quenching. However, once a galaxy is quenched, changes in star formation efficiency drive how much a retired galaxy differs in its star formation rate from star-forming ones of similar masses. In other words, once a paucity of molecular gas has significantly reduced star formation, changes in the star formation efficiency are what drives a galaxy deeper into the red cloud, hence retiring it.

scholarly journals Wide Field Star Count Mapping of Large Scale Areas of Star Formation in the Large Magellanic Cloud

1994 ◽  
Vol 161 ◽  
pp. 516-517 ◽  
Author(s):  
E. Kontizas ◽  
S.E. Maravelias ◽  
A. Dapergolas ◽  
Y. Bellas-Velidis ◽  
M. Kontizas
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Large Magellanic Cloud ◽  
Wide Field ◽  
Dark Clouds ◽  
Star Count ◽  
Astrophysical Problem ◽  
Star Formation In Galaxies ◽  
The Individual ◽  
Parent Galaxy

Star formation in galaxies is a major astrophysical problem which can be investigated in several ways. The distribution and loci of all kinds of young objects, including OB associations, young clusters, HII regions, GMCs, Bok globules, dark clouds, dust lanes, protostars, as well as YSOs detected in NIR and FIR surveys constitute the principal signposts for this investigation. The individual nature of all these objects has been and is still continously studied. However it is also extremely interesting to associate the coexistence of these objects, and their relation to the structure of the parent galaxy. Such studies have been carried out by several investigators and are frequently summarized when star formation processes are examined.

scholarly journals Centrally concentrated molecular gas driving galactic-scale ionized gas outflows in star-forming galaxies

2020 ◽  
Vol 500 (3) ◽  
pp. 3802-3820
Author(s):  
L M Hogarth ◽  
A Saintonge ◽  
L Cortese ◽  
T A Davis ◽  
S M Croom ◽  
...  
Keyword(s):  
Star Formation ◽  
Spatial Resolution ◽  
Large Scale ◽  
Formation Rate ◽  
Control Sample ◽  
Joint Analysis ◽  
Molecular Gas ◽  
Ionized Gas ◽  
Data Set ◽  
Star Forming

ABSTRACT We perform a joint analysis of high spatial resolution molecular gas and star-formation rate (SFR) maps in main-sequence star-forming galaxies experiencing galactic-scale outflows of ionized gas. Our aim is to understand the mechanism that determines which galaxies are able to launch these intense winds. We observed CO(1→0) at 1-arcsec resolution with ALMA in 16 edge-on galaxies, which also have 2-arcsec spatial-resolution optical integral field observations from the SAMI Galaxy Survey. Half the galaxies in the sample were previously identified as harbouring intense and large-scale outflows of ionized gas (‘outflow types’) and the rest serve as control galaxies. The data set is complemented by integrated CO(1→0) observations from the IRAM 30-m telescope to probe the total molecular gas reservoirs. We find that the galaxies powering outflows do not possess significantly different global gas fractions or star-formation efficiencies when compared with a control sample. However, the ALMA maps reveal that the molecular gas in the outflow-type galaxies is distributed more centrally than in the control galaxies. For our outflow-type objects, molecular gas and star-formation are largely confined within their inner effective radius (reff), whereas in the control sample, the distribution is more diffuse, extending far beyond reff. We infer that outflows in normal star-forming galaxies may be caused by dynamical mechanisms that drive molecular gas into their central regions, which can result in locally enhanced gas surface density and star-formation.

scholarly journals The link between star formation and gas in nearby galaxies

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Robert Feldmann
Keyword(s):  
Star Formation ◽  
Gas Content ◽  
Molecular Gas ◽  
Galaxy Mergers ◽  
Physical Processes ◽  
Star Forming ◽  
Star Formation Activity ◽  
Star Formation In Galaxies ◽  
Nearby Galaxies ◽  
Gas Accretion

AbstractObservations of the interstellar medium are key to deciphering the physical processes regulating star formation in galaxies. However, observational uncertainties and detection limits can bias the interpretation unless carefully modeled. Here I re-analyze star formation rates and gas masses of a representative sample of nearby galaxies with the help of multi-dimensional Bayesian modeling. Typical star forming galaxies are found to lie in a ‘star forming plane’ largely independent of their stellar mass. Their star formation activity is tightly correlated with the molecular and total gas content, while variations of the molecular-gas-to-star conversion efficiency are shown to be significantly smaller than previously reported. These data-driven findings suggest that physical processes that modify the overall galactic gas content, such as gas accretion and outflows, regulate the star formation activity in typical nearby galaxies, while a change in efficiency triggered by, e.g., galaxy mergers or gas instabilities, may boost the activity of starbursts.

scholarly journals The properties of radio and mid-infrared detected galaxies and the effect of environment on the co-evolution of AGN and star formation at z ∼ 1

2020 ◽  
Vol 494 (4) ◽  
pp. 5374-5395 ◽  
Author(s):  
Lu Shen ◽  
Brian C Lemaux ◽  
Lori M Lubin ◽  
John McKean ◽  
Neal A Miller ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Formation Rate ◽  
Rapid Quenching ◽  
Radio Luminosity ◽  
Star Forming ◽  
Cluster Group ◽  
Significant Difference ◽  
Almost All ◽  
Quenching Time

ABSTRACT In this study, we investigate 179 radio-infrared (IR) galaxies drawn from a sample of spectroscopically confirmed galaxies, which are detected in radio and mid-IR (MIR) in the redshift range of 0.55 ≤ z ≤ 1.30 in the Observations of Redshift Evolution in Large Scale Environments (ORELSE) survey. We constrain the active galactic nuclei (AGN) contribution to the total IR luminosity (fAGN), and estimate the AGN luminosity (LAGN) and the star formation rate (SFR). Based on the fAGN and radio luminosity, radio–IR galaxies are split into galaxies that host either high- or low-fAGN AGN (high-/low-fAGN), and star-forming galaxies (SFGs) with little to no AGN activity. We study the properties of the three radio–IR sub-samples comparing to an underlying parent sample. In the comparison of radio luminosity of three sub-samples, no significant difference was found, which could be due to the combined contribution of radio emission from AGN and star formation. We find a positive relationship between LAGN and specific SFR (sSFR) for both AGN sub-samples, strongly suggesting a co-evolution scenario of AGN and SF in these galaxies. A toy model is designed to demonstrate this co-evolution scenario, where we find that, in almost all cases, a rapid quenching time-scale is required, which we argue is a signature of AGN quenching. The environmental preference for intermediate/infall regions of clusters/groups remains across the co-evolution scenario, which suggests that galaxies might be in an orbital motion around the cluster/group during the scenario.

scholarly journals Clues on Arp 142: The spiral–elliptical merger

2019 ◽  
Vol 488 (1) ◽  
pp. 830-846
Author(s):  
Marcelo D Mora ◽  
Sergio Torres-Flores ◽  
Verónica Firpo ◽  
Jose A Hernandez-Jimenez ◽  
Fernanda Urrutia-Viscarra ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Morphological Characteristics ◽  
Current Data ◽  
Ionization Mechanism ◽  
H Ii Regions ◽  
Data Set ◽  
Star Forming ◽  
Star Forming Regions ◽  
The Individual

Abstract Nearby merging pairs are unique laboratories in which one can study the gravitational effects on the individual interacting components. In this manuscript, we report the characterization of selected H ii regions along the peculiar galaxy NGC 2936, member of the galaxy pair Arp 142, an E+S interaction, known as ‘The Penguin’. Using Gemini South spectroscopy, we have derived a high enhancement of the global star formation rate (SFR) = 35.9 M⊙ yr−1 probably stimulated by the interaction. Star-forming regions on this galaxy display oxygen abundances that are consistent with solar metallicities. The current data set does not allow us to conclude any clear scenario for NGC 2936. Diagnostic diagrams suggest that the central region of NGC 2936 is ionized by active galactic nucleus (AGN) activity and the eastern tidal plume in NGC 2936 is experiencing a burst of star formation, which may be triggered by the gas compression due to the interaction event with its elliptical companion galaxy: NGC 2937. The ionization mechanism of these sources is consistent with shock models of low velocities of 200–300 km s −1. The isophotal analysis shows tidal features on NGC 2937: at inner radii non-concentric (or off-centring) isophotes, and at large radii, a faint excess of the surface brightness profile with respect to de Vaucouleurs law. By comparing the radial velocity profiles and morphological characteristics of Arp 142 with a library of numerical simulations, we conclude that the current stage of the system would be about 50 ± 25 Myr after the first pericentre passage.

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