scholarly journals ALMA unveils wider environment of distant red protocluster core

2020 ◽  
Vol 496 (4) ◽  
pp. 4358-4365 ◽  
Author(s):  
R J Ivison ◽  
A D Biggs ◽  
M Bremer ◽  
V Arumugam ◽  
L Dunne
Keyword(s):  
Star Formation ◽  
Active Phase ◽  
Molecular Gas ◽  
Gas Reservoirs ◽  
Short Baseline ◽  
New Members ◽  
Line Imaging ◽  
A Site ◽  
Red Core

ABSTRACT We report observations with the Atacama Large Millimetre Array (ALMA) of six submillimetre galaxies (SMGs) within 3 arcmin of the Distant Red Core (DRC) at z = 4.0, a site of intense cluster-scale star formation, first reported by Oteo et al. We find new members of DRC in three SMG fields; in two fields, the SMGs are shown to lie along the line of sight towards DRC; one SMG is spurious. Although at first sight this rate of association is consistent with earlier predictions, associations with the bright SMGs are rarer than expected, which suggests caution when interpreting continuum overdensities. We consider the implications of all 14 confirmed DRC components passing simultaneously through an active phase of star formation. In the simplest explanation, we see only the tip of the iceberg in terms of star formation and gas available for future star formation, consistent with our remarkable finding that the majority of newly confirmed DRC galaxies are not the brightest continuum emitters in their immediate vicinity. Thus, while ALMA continuum follow-up of SMGs identifies the brightest continuum emitters in each field, it does not necessarily reveal all the gas-rich galaxies. To hunt effectively for protocluster members requires wide and deep spectral-line imaging to uncover any relatively continuum-faint galaxies that are rich in atomic or molecular gas. Searching with short-baseline arrays or single-dish facilities, the true scale of the underlying gas reservoirs may be revealed.

scholarly journals ALMA reveals large molecular gas reservoirs in recently-quenched galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 199-199
Author(s):  
Katherine Suess
Keyword(s):  
Star Formation ◽  
Rapid Quenching ◽  
Molecular Gas ◽  
Gas Reservoirs ◽  
Physical Mechanisms ◽  
Quenching Process ◽  
Star Formation In Galaxies ◽  
Gas Fractions ◽  
The Ideal

AbstractWe still do not understand the physical mechanisms that are responsible for suppressing star formation in galaxies. Observations of post-starburst galaxies, whose spectra indicate that an intense period of star formation was followed by rapid quenching, are the ideal sample to probe the quenching process. We have conducted an ALMA survey of CO(2-1) in 13 of these recently- quenched galaxies at z ∼ 0.7 – high enough redshift that these galaxies likely just concluded their primary epoch of star formation, but low enough redshift for follow-up observations to be feasible. Our observations reveal a stunning diversity of molecular gas properties: despite a uniform optical selection and low apparent SFRs, the detected galaxies span a factor of > 30 in CO luminosity and have inferred gas fractions ranging from < 1% to 20%. These observations indicate that quenching does not require the total removal or depletion of molecular gas. No current models of the quenching process can fully explain our results.

scholarly journals High molecular gas content and star formation rates in local galaxies that host quasars, outflows, and jets

2020 ◽  
Vol 498 (2) ◽  
pp. 1560-1575 ◽  
Author(s):  
M E Jarvis ◽  
C M Harrison ◽  
V Mainieri ◽  
G Calistro Rivera ◽  
P Jethwa ◽  
...  
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Gas Content ◽  
Molecular Gas ◽  
Host Galaxies ◽  
Gas Reservoirs ◽  
Galaxy Population ◽  
Stellar Masses ◽  
Gas Fractions

ABSTRACT We use a sample of powerful $z\, \approx \, 0.1$ type 2 quasars (‘obscured’; log [LAGN/erg s$^{-1}]\, \gtrsim \, 45$), which host kpc-scale ionized outflows and jets, to identify possible signatures of AGN feedback on the total molecular gas reservoirs of their host galaxies. Specifically, we present Atacama Pathfinder EXperiment (APEX) observations of the CO(2–1) transition for nine sources and the CO(6–5) for a subset of three. We find that the majority of our sample reside in starburst galaxies (average specific star formation rates – sSFR – of 1.7 Gyr−1), with the seven CO-detected quasars also having large molecular gas reservoirs (average Mgas = 1.3 × 1010 M⊙), even though we had no pre-selection on the star formation or molecular gas properties. Despite the presence of quasars and outflows, we find that the molecular gas fractions (Mgas/M⋆ = 0.1–1.2) and depletion times (Mgas/SFR = 0.16–0.95 Gyr) are consistent with those expected for the overall galaxy population with matched stellar masses and sSFRs. Furthermore, for at least two of the three targets with the required measurements, the CO(6–5)/CO(2–1) emission-line ratios are consistent with star formation dominating the CO excitation over this range of transitions. The targets in our study represent a gas-rich phase of galaxy evolution with simultaneously high levels of star formation and nuclear activity; furthermore, the jets and outflows do not have an immediate appreciable impact on the global molecular gas reservoirs.

scholarly journals Constraining star formation timescales with molecular gas and young star clusters

2019 ◽  
Vol 15 (S352) ◽  
pp. 350-352
Author(s):  
Kathryn Grasha ◽  
Daniela Calzetti
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Star Clusters ◽  
Young Star ◽  
Molecular Gas ◽  
Gas Reservoirs ◽  
Multi Wavelength ◽  
Predictive Theory ◽  
Young Star Clusters ◽  
Co Observations

AbstractStar formation provides insight into the physical processes that govern the transformation of gas into stars. A key missing piece in a predictive theory of star formation is the link between scales of individual stars and star clusters up to entire galaxies. LEGUS is now providing the information to test the overall organization and spatial evolution of star formation. We present our latest findings of using star clusters from LEGUS combined with ALMA CO observations to investigate the transition from molecular gas to star formation in local galaxies. This work paves the way for future JWST observations of the embedded phase of star formation, the last missing ingredient to connect young star clusters and their relation with gas reservoirs. Multi-wavelength studies of local galaxies and their stellar and gas components will help shed light on early phases of galaxy evolution and properties of the ISM at high-z.

scholarly journals Deep CO(1–0) Observations ofz= 1.62 Cluster Galaxies with Substantial Molecular Gas Reservoirs and Normal Star Formation Efficiencies

2017 ◽  
Vol 849 (1) ◽  
pp. 27 ◽  
Author(s):  
Gregory Rudnick ◽  
Jacqueline Hodge ◽  
Fabian Walter ◽  
Ivelina Momcheva ◽  
Kim-Vy Tran ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Gas ◽  
Gas Reservoirs ◽  
Cluster Galaxies ◽  
Normal Star

scholarly journals Inflow of atomic gas fuelling star formation

2015 ◽  
Vol 11 (A29B) ◽  
pp. 229-230
Author(s):  
M. J. Michałowski ◽  
G. Gentile ◽  
J. Hjorth ◽  
M. R. Krumholz ◽  
N. R. Tanvir ◽  
...  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
Molecular Gas ◽  
Host Galaxies ◽  
Gas Reservoirs ◽  
Gamma Ray Burst ◽  
Gas Cooling ◽  
Low Metallicity ◽  
Atomic Gas ◽  
Compact Array

AbstractGamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation in these galaxies may be fuelled by recent inflow of metal-poor atomic gas. While this process is debated, it can happen in low-metallicity gas near the onset of star formation because gas cooling (necessary for star formation) is faster than the Hi-to-H2 conversion.

scholarly journals AlFoCS + Fornax3D: resolved star formation in the Fornax cluster with ALMA and MUSE

2020 ◽  
Vol 496 (2) ◽  
pp. 2155-2182 ◽  
Author(s):  
N Zabel ◽  
T A Davis ◽  
M Sarzi ◽  
Boris Nedelchev ◽  
M Chevance ◽  
...  
Keyword(s):  
Star Formation ◽  
Dwarf Galaxy ◽  
Formation Rate ◽  
Mass Range ◽  
Stellar Mass ◽  
Small Scale ◽  
Molecular Gas ◽  
Gas Reservoirs ◽  
Cluster Galaxies ◽  
Fornax Cluster

ABSTRACT We combine data from ALMA and MUSE to study the resolved (∼300 pc scale) star formation relation (star formation rate, SFR, versus molecular gas surface density) in cluster galaxies. Our sample consists of nine Fornax cluster galaxies, including spirals, ellipticals, and dwarfs, covering a stellar mass range of ∼108.8–1011 M⊙. CO(1-0) and extinction corrected Hα were used as tracers for the molecular gas mass and SFR, respectively. We compare our results with Kennicutt and Bigiel et al. Furthermore, we create depletion time maps to reveal small-scale variations in individual galaxies. We explore these further in FCC290, using the ‘uncertainty principle for star formation’ (Kruijssen & Longmore) to estimate molecular cloud lifetimes, which we find to be short (&lt;10 Myr) in this galaxy. Galaxy-averaged depletion times are compared with other parameters such as stellar mass and cluster-centric distance. We find that the star formation relation in the Fornax cluster is close to those from Kennicutt and Bigiel et al., but overlaps mostly with the shortest depletion times predicted by Bigiel et al. This slight decrease in depletion time is mostly driven by dwarf galaxies with disturbed molecular gas reservoirs close to the virial radius. In FCC90, a dwarf galaxy with a molecular gas tail, we find that depletion times are a factor ≳10 higher in its tail than in its stellar body.

Revealing the origin of the cold ISM in massive early-type galaxies

2012 ◽  
Vol 8 (S295) ◽  
pp. 324-327
Author(s):  
T. A. Davis ◽  
K. Alatalo ◽  
M. Bureau ◽  
L. Young ◽  
L. Blitz ◽  
...  
Keyword(s):  
Star Formation ◽  
Virgo Cluster ◽  
Molecular Gas ◽  
Strong Impact ◽  
Early Type ◽  
Gas Reservoirs ◽  
Massive Galaxies ◽  
Gas Accretion ◽  
Gas Supply ◽  
Cold Gas

AbstractRecently, massive early-type galaxies have shed their red-and-dead moniker, thanks to the discovery that many host residual star formation. As part of the ATLAS-3D project, we have conducted a complete, volume-limited survey of the molecular gas in 260 local early-type galaxies with the IRAM-30m telescope and the CARMA interferometer, in an attempt to understand the fuel powering this star formation. We find that around 22% of early-type galaxies in the local volume host molecular gas reservoirs. This detection rate is independent of galaxy luminosity and environment. Here we focus on how kinematic misalignment measurements and gas-to-dust ratios can be used to put constraints on the origin of the cold ISM in these systems. The origin of the cold ISM seems to depend strongly on environment, with misaligned, dust poor gas (indicative of externally acquired material) being common in the field but completely absent in rich groups and in the Virgo cluster. Very massive galaxies also appear to be devoid of accreted gas. This suggests that in the field mergers and/or cold gas accretion dominate the gas supply, while in clusters internal secular processes become more important. This implies that environment has a strong impact on the cold gas properties of ETGs.

scholarly journals Dense-gas tracers and carbon isotopes in five 2.5 < z < 4 lensed dusty star-forming galaxies from the SPT SMG sample

2018 ◽  
Vol 620 ◽  
pp. A115 ◽  
Author(s):  
M. Béthermin ◽  
T. R. Greve ◽  
C. De Breuck ◽  
J. D. Vieira ◽  
M. Aravena ◽  
...  
Keyword(s):  
Star Formation ◽  
Signal To Noise Ratio ◽  
High Redshift ◽  
Flux Ratio ◽  
Molecular Gas ◽  
Dense Gas ◽  
Gas Reservoirs ◽  
Star Forming ◽  
South Pole Telescope ◽  
Galaxy Sample

The origin of the high star formation rates (SFR) observed in high-redshift dusty star-forming galaxies is still unknown. Large fractions of dense molecular gas might provide part of the explanation, but there are few observational constraints on the amount of dense gas in high-redshift systems dominated by star formation. In this paper, we present the results of our Atacama large millimeter array (ALMA) program targeting dense-gas tracers (HCN(5-4), HCO+(5-4), and HNC(5-4)) in five strongly lensed galaxies from the South Pole Telescope (SPT) submillimeter galaxy sample. We detected two of these lines (S/N > 5) in SPT-125-47 at z = 2.51 and tentatively detected all three (S/N ∼ 3) in SPT0551-50 at z = 3.16. Since a significant fraction of our target lines is not detected, we developed a statistical method to derive unbiased mean properties of our sample taking into account both detections and non-detections. On average, the HCN(5-4) and HCO+(5-4) luminosities of our sources are a factor of ∼1.7 fainter than expected, based on the local L′HCN(5-4) − LIR relation, but this offset corresponds to only ∼2σ if we consider sample variance. We find that both the HCO+/HCN and HNC/HCN flux ratios are compatible with unity. The first ratio is expected for photo-dominated regions (PDRs) while the second is consistent with PDRs or X-ray dominated regions (XDRs) and/or mid-infrared (IR) pumping of HNC. Our sources are at the high end of the local relation between the star formation efficiency, determined using the LIR/[CI] and LIR/CO ratios, and the dense-gas fraction, estimated using the HCN/[CI] and HCN/CO ratios. Finally, in SPT0125-47, which has the highest signal-to-noise ratio, we found that the velocity profiles of the lines tracing dense (HCN, HCO+) and lower-density (CO, [CI]) molecular gas are similar. In addition to these lines, we obtained one robust and one tentative detection of 13CO(4-3) and found an average I 12CO(4-3)/I13CO(4-3) flux ratio of 26.1−3.5+4.5, indicating a young but not pristine interstellar medium. We argue that the combination of large and slightly enriched gas reservoirs and high dense-gas fractions could explain the prodigious star formation in these systems.

scholarly journals More than star formation: High-J CO SLEDs of high-z galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 162-167
Author(s):  
Chelsea E. Sharon ◽  
Reni Chng ◽  
Kebron K. Gurara ◽  
Axel Weiß ◽  
Jeremy Darling ◽  
...  
Keyword(s):  
Star Formation ◽  
Theoretical Work ◽  
Molecular Gas ◽  
Gas Reservoirs ◽  
Local Universe ◽  
Line Energy ◽  
Massive Galaxies ◽  
Molecular Outflows ◽  
Very High ◽  
Co Emission

AbstractTheoretical work suggests that AGNs play an important role in quenching star formation in massive galaxies. In addition to molecular outflows observed in the local universe, emission from very high-J CO rotational transitions have been a key piece of evidence for AGN directly affecting the molecular gas reservoirs that fuel star formation. However, very few observations exist of CO rotational lines past the peak of the CO spectral line energy distribution (SLED) for galaxies in the early universe. Here we present new ALMA observations of high-J CO rotational lines (from CO(5–4) to CO(16–15)) in six z > 2 IR-bright systems, including several sources not known to contain a strong AGN for comparison. We detect significant amounts of high-excitation CO emission that suggests the presence of energy sources beyond UV-heating.

scholarly journals Exhausted gas reservoirs drive massive galaxy quenching in the early universe

2020 ◽  
Author(s):  
Katherine Whitaker ◽  
Christina Williams ◽  
Lamiya Mowla ◽  
Justin Spilker ◽  
Sune Toft ◽  
...  
Keyword(s):  
Star Formation ◽  
Molecular Gas ◽  
Dark Matter Halos ◽  
Gas Reservoirs ◽  
Massive Galaxies ◽  
Star Forming ◽  
Early Galaxies ◽  
Stellar Masses ◽  
Cold Dust ◽  
The Universe

Abstract When the Universe was merely three billion years old, about half of massive galaxies had already formed the bulk of their stars and new star formation plummeted [1]. How galaxies quench at such early times remains a puzzle, as their dark matter halos contain large gas reservoirs [2-4]. This gas should cool efficiently, sustaining star formation over long periods [5,6]. Here we present sensitive 1.3mm wavelength observations of cold dust in six quenched galaxies in the redshift range z=1.6 to z=3.2 with stellar masses ranging from 2.5x1010M⊙ to 5x1011M⊙, which are magnified by foreground galaxy clusters. Even with factors of up to 30 in magnification, four of the six galaxies are undetected at this wavelength. We show that these quenched galaxies have extremely little dust at early times, and by proxy very little cold molecular gas. The median dust mass is <0.01% of the stellar mass (molecular gas mass <1%), more than two orders of magnitude less than star-forming galaxies at this epoch [4]. The implication is that most early galaxies shut off star formation because their reservoir of molecular gas was rapidly depleted or removed, and is not being replenished.

Sign in / Sign up

Export Citation Format

Share Document