ALMA observations of massive molecular gas reservoirs in dusty early-type galaxies

ABSTRACT In this paper, we study the molecular gas content of a representative sample of 67 of the most massive early-type galaxies (ETGs) in the local universe, drawn uniformly from the MASSIVE survey. We present new Institut de Radioastronomie Millimétrique (IRAM) 30-m telescope observations of 30 of these galaxies, allowing us to probe the molecular gas content of the entire sample to a fixed molecular-to-stellar mass fraction of 0.1 per cent. The total detection rate in this representative sample is 25$^{+5.9}_{-4.4}$ per cent, and by combining the MASSIVE and atlas3D molecular gas surveys, we find a joint detection rate of 22.4$^{+2.4}_{-2.1}$ per cent. This detection rate seems to be independent of galaxy mass, size, position on the Fundamental Plane, and local environment. We show here for the first time that true slow rotators can host molecular gas reservoirs, but the rate at which they do so is significantly lower than for fast rotators. Objects with a higher velocity dispersion at fixed mass (a higher kinematic bulge fraction) are less likely to have detectable molecular gas, and where gas does exist, have lower molecular gas fractions. In addition, satellite galaxies in dense environments have ≈0.6 dex lower molecular gas-to-stellar mass ratios than isolated objects. In order to interpret these results, we created a toy model, which we use to constrain the origin of the gas in these systems. We are able to derive an independent estimate of the gas-rich merger rate in the low-redshift universe. These gas-rich mergers appear to dominate the supply of gas to ETGs, but stellar mass loss, hot halo cooling, and transformation of spiral galaxies also play a secondary role.

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Spatially resolved molecular gas in early-type galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314004840 ◽

2012 ◽

Vol 10 (H16) ◽

pp. 122-123

Author(s):

T. A. Davis ◽

K. Alatalo ◽

M. Bureau ◽

L. Young ◽

L. Blitz ◽

...

Keyword(s):

Virgo Cluster ◽

Molecular Gas ◽

Early Type ◽

Gas Reservoirs ◽

Element Abundances ◽

Spatially Resolved ◽

Radiation Fields ◽

Uv Emission ◽

The Many ◽

High Metallicity

AbstractIn around ≈25% of early-type galaxies (ETGs) UV emission from young stellar populations is present. Molecular gas reservoirs have been detected in these systems (e.g. Young et al. (2011), providing the fuel for this residual star-formation. The environment in which this molecular gas is found is quite different than that in spiral galaxies however, with harsher radiation fields, deeper potentials and high metallicity and alpha-element abundances. Here we report on one element of our multi-faceted programme to understand the similarities and differences between the gas reservoirs in spirals and ETGs. We use spatially resolved observations from the CARMA mm-wave interferometer to investigate the size of the molecular reservoirs in the the CO-rich ATLAS3D ETGs (survey described in Alatalo et al. 2012, submitted). We find that the molecular gas extent is smaller in absolute terms in ETGs than in late-type galaxies, but that the size distributions are similar once scaled by the galaxies optical/stellar characteristic scale-lengths (Fig 1, left). Amongst ETGs, we find that the extent of the molecular gas is independent of the kinematic misalignment, despite the many reasons why misaligned gas might have a smaller extent. The extent of the molecular gas does depend on environment, with Virgo cluster ETGs having less extended molecular gas reservoirs (Fig 1, right). Whatever the cause, this further emphases that cluster ETGs follow different evolutionary pathways from those in the field. Full details of this work will be presented in Davis et al. (2012), submitted.

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Cold gas in a complete sample of group-dominant early-type galaxies

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833580 ◽

2018 ◽

Vol 618 ◽

pp. A126 ◽

Cited By ~ 13

Author(s):

E. O’Sullivan ◽

F. Combes ◽

P. Salomé ◽

L.P. David ◽

A. Babul ◽

...

Keyword(s):

Virgo Cluster ◽

Morphological Data ◽

Molecular Gas ◽

Early Type ◽

Radio Luminosity ◽

Dominant Group ◽

Gas Reservoirs ◽

X Ray ◽

Using Data ◽

Cold Gas

We present IRAM 30 m and APEX telescope observations of CO(1-0) and CO(2-1) lines in 36 group-dominant early-type galaxies, completing our molecular gas survey of dominant galaxies in the Complete Local-volume Groups Sample. We detect CO emission in 12 of the galaxies at > 4σ significance, with molecular gas masses in the range ∼ 0.01 − 6 × 108 M⊙, as well as CO in absorption in the non-dominant group member galaxy NGC 5354. In total 21 of the 53 CLoGS dominant galaxies are detected in CO and we confirm our previous findings that they have low star formation rates (0.01–1 M⊙yr−1) but short depletion times (>1 Gyr) implying rapid replenishment of their gas reservoirs. Comparing molecular gas mass with radio luminosity, we find that a much higher fraction of our group-dominant galaxies (60 ± 16%) are AGN-dominated than is the case for the general population of ellipticals, but that there is no clear connection between radio luminosity and the molecular gas mass. Using data from the literature, we find that at least 27 of the 53 CLoGS dominant galaxies contain H I, comparable to the fraction of nearby non-cluster early type galaxies detected in H I and significantly higher that the fraction in the Virgo cluster. We see no correlation between the presence of an X-ray detected intra-group medium and molecular gas in the dominant galaxy, but find that the H I-richest galaxies are located in X-ray faint groups. Morphological data from the literature suggests the cold gas component most commonly takes the form of a disk, but many systems show evidence of galaxy-galaxy interactions, indicating that they may have acquired their gas through stripping or mergers. We provide improved molecular gas mass estimates for two galaxies previously identified as being in the centres of cooling flows, NGC 4636 and NGC 5846, and find that they are relatively molecular gas poor compared to our other detected systems.

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

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313005267 ◽

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.

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An ALMA/NOEMA survey of the molecular gas properties of high-redshift star-forming galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3862 ◽

2020 ◽

Author(s):

Jack E Birkin ◽

Axel Weiss ◽

J L Wardlow ◽

Ian Smail ◽

A M Swinbank ◽

...

Keyword(s):

High Redshift ◽

Strong Support ◽

Molecular Gas ◽

Early Type ◽

Coma Cluster ◽

Gas Reservoirs ◽

Line Energy ◽

Star Forming ◽

Flux Limit ◽

Baryonic Mass

Abstract We have used ALMA and NOEMA to study the molecular gas reservoirs in 61 ALMA-identified submillimetre galaxies (SMGs) in the COSMOS, UDS and ECDFS fields. We detect 12CO (Jup = 2–5) emission lines in 50 sources, and [C i](3P1 − 3P0) emission in eight, at z = 1.2–4.8 and with a median redshift of 2.9 ± 0.2. By supplementing our data with literature sources we construct a statistical CO spectral line energy distribution and find that the 12CO line luminosities in SMGs peak at Jup ∼ 6, consistent with similar studies. We also test the correlations of the CO, [C i] and dust as tracers of the gas mass, finding the three to correlate well, although the CO and dust mass as estimated from the 3-mm continuum are preferable. We estimate that SMGs lie mostly on or just above the star-forming main sequence, with a median gas depletion timescale, tdep = Mgas/SFR, of 210 ± 40 Myr for our sample. Additionally, tdep declines with redshift across z ∼ 1–5, while the molecular gas fraction, μgas = Mgas/M*, increases across the same redshift range. Finally, we demonstrate that the distribution of total baryonic mass and dynamical line width, Mbaryon–σ, for our SMGs is consistent with that followed by early-type galaxies in the Coma cluster, providing strong support to the suggestion that SMGs are progenitors of massive local spheroidal galaxies. On the basis of this we suggest that the SMG populations above and below an 870-μm flux limit of S870 ∼ 5 mJy may correspond to the division between slow- and fast-rotators seen in local early-type galaxies.

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DESTRUCTION OF MOLECULAR GAS RESERVOIRS IN EARLY-TYPE GALAXIES BY ACTIVE GALACTIC NUCLEUS FEEDBACK

The Astrophysical Journal ◽

10.1088/0004-637x/690/2/1672 ◽

2008 ◽

Vol 690 (2) ◽

pp. 1672-1680 ◽

Cited By ~ 66

Author(s):

Kevin Schawinski ◽

Chris J. Lintott ◽

Daniel Thomas ◽

Sugata Kaviraj ◽

Serena Viti ◽

...

Keyword(s):

Active Galactic Nucleus ◽

Molecular Gas ◽

Early Type ◽

Gas Reservoirs

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Cold gas and dust: Hunting spiral-like structures in early-type galaxies

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935090 ◽

2020 ◽

Vol 636 ◽

pp. A8 ◽

Cited By ~ 1

Author(s):

M. K. Yıldız ◽

R. F. Peletier ◽

P.-A. Duc ◽

P. Serra

Keyword(s):

Large Scale ◽

Neutral Hydrogen ◽

Molecular Gas ◽

Early Type ◽

Gas Reservoirs ◽

Good Correspondence ◽

Long Time ◽

Dust Detection ◽

Gas Accretion ◽

Cold Gas

Context. Observations of neutral hydrogen (H I) and molecular gas show that 50% of all nearby early-type galaxies contain some cold gas. Molecular gas is always found in small gas discs in the central region of the galaxy, while neutral hydrogen is often distributed in a low-column density disc or ring typically extending well beyond the stellar body. Dust is frequently found in early-type galaxies as well. Aims. The goal of our study is to understand the link between dust and cold gas in nearby early-type galaxies as a function of H I content. Methods. We analyse deep optical g − r images obtained with the MegaCam camera at the Canada-France-Hawaii Telescope for a sample of 21 H I-rich and 41 H I-poor early-type galaxies. Results. We find that all H I-rich galaxies contain dust seen as absorption. Moreover, in 57% of these H I-rich galaxies, the dust is distributed in a large-scale spiral pattern. Although the dust detection rate is relatively high in the H I-poor galaxies (∼59%), most of these systems exhibit simpler dust morphologies without any evidence of spiral structures. We find that the H I-rich galaxies possess more complex dust morphology extending to almost two times larger radii than H I-poor objects. We measured the dust content of the galaxies from the optical colour excess and find that H I-rich galaxies contain six times more dust (in mass) than H I-poor ones. In order to maintain the dust structures in the galaxies, continuous gas accretion is needed, and the substantial H I gas reservoirs in the outer regions of early-type galaxies can satisfy this need for a long time. We find that there is a good correspondence between the observed masses of the gas and dust, and it is also clear that dust is present in regions further than 3 Reff. Conclusions. Our findings indicate an essential relation between the presence of cold gas and dust in early-type galaxies and offer a way to study the interstellar medium in more detail than what is possible with H I observations.

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5.18. Molecular gas in the poststarburst galaxy NGC7331

Symposium - International Astronomical Union ◽

10.1017/s0074180900084801 ◽

1998 ◽

Vol 184 ◽

pp. 247-248

Author(s):

T. Tosaki ◽

Y. Shioya

Keyword(s):

High Resolution ◽

Spiral Galaxy ◽

Stellar Populations ◽

Optical Spectra ◽

Molecular Gas ◽

Early Type ◽

Origin And Evolution ◽

Co Observations

To understand the origin and evolution of starburst activity, we must study the full evolution of starburst; i.e., pre-, on-going, and post-starburst phases. It seems reasonable to suppose the numerous A-type stars indicate past starburst and they show strong Balmer absorption. NGC7331, nearby early-type spiral galaxy, is one of the poststarburst galaxies which show strong Balmer absorption. The optical spectra of NGC7331 were dominated by component of intermediate-age (5 × 109 years) stellar populations (Ohyama & Taniguchi 1996). We present the result of the high resolution CO observations of NGC7331 using Nobeyama Milimeter Array.

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