Atomic Hydrogen and Star Formation in the Bridge/Ring Interacting Galaxy Pair NGC 7714/7715 (Arp 284)

1997 ◽  
Vol 483 (2) ◽  
pp. 754-766 ◽  
Author(s):  
Beverly J. Smith ◽  
Curtis Struck ◽  
Richard W. Pogge
Keyword(s):  
Star Formation ◽  
Atomic Hydrogen

scholarly journals The SFR Efficiency of HI Gas in the Outskirts of Star Forming Galaxies

2016 ◽  
Vol 11 (S321) ◽  
pp. 360-362
Author(s):  
Marc Rafelski
Keyword(s):  
Star Formation ◽  
Atomic Hydrogen ◽  
Rest Frame ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Hydrogen Gas ◽  
Star Forming ◽  
Uv Emission ◽  
Atomic Gas

AbstractIn order to understand the origin of the decreased star formation rate (SFR) efficiency of neutral atomic hydrogen gas measured in Damped Lyα Systems (DLAs) at z ~ 3, we measure the SFR efficiency of atomic gas at z ~ 1, z ~ 2, and z ~ 3 around star-forming galaxies. We create galaxy stacks in these three redshift bins, and measure the SFR efficiency by combining DLA absorber statistics with the observed rest-frame UV emission in the galaxies’ outskirts. We find that the SFR efficiency of Hi gas is ~ 3% of that predicted by the KS relation. We find no significant evolution in the SFR efficiency with redshift, although simulations and models predict a decreasing SFR efficiency with decreasing metallicity and thus with increasing redshift. We discuss possible explanations for this decreased efficiency without an evolution with redshift.

scholarly journals Atomic hydrogen, star formation and feedback in the lowest mass blue compact dwarf galaxies

2012 ◽  
Vol 426 (1) ◽  
pp. 665-672 ◽  
Author(s):  
Sambit Roychowdhury ◽  
Jayaram N. Chengalur ◽  
Kristin Chiboucas ◽  
Igor D. Karachentsev ◽  
R. Brent Tully ◽  
...  
Keyword(s):  
Star Formation ◽  
Atomic Hydrogen ◽  
Dwarf Galaxies

scholarly journals Appendix. Molecular Hydrogen in the Interstellar Gas

1970 ◽  
Vol 39 ◽  
pp. 320-321
Author(s):  
E. E. Salpeter
Keyword(s):  
Star Formation ◽  
Cooling Rate ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Galactic Disk ◽  
Interstellar Gas

There are two levels of interest in the abundance of molecular hydrogen in the interstellar gas. (i) Even a low abundance can enhance the cooling rate at a few hundred K. (ii) Densities comparable with or larger than those of atomic hydrogen could affect the dynamics in the galactic disk, if widespread, or at least affect star formation, if restricted to isolated large clouds.

scholarly journals A statistical measurement of the H i spin temperature in DLAs at cosmological distances

2021 ◽  
Author(s):  
James R Allison
Keyword(s):  
Star Formation ◽  
Atomic Hydrogen ◽  
Milky Way ◽  
Star Formation Rate ◽  
Mass Density ◽  
Formation Rate ◽  
Neutral Medium ◽  
Molecular Gas ◽  
Spin Temperature ◽  
Order Of Magnitude

Abstract Evolution of the cosmic star formation rate (SFR) and molecular mass density is expected to be matched by a similarly strong evolution of the fraction of atomic hydrogen (H i) in the cold neutral medium (CNM). We use results from a recent commissioning survey for intervening 21-cm absorbers with the Australian Square Kilometre Array Pathfinder (ASKAP) to construct a Bayesian statistical model of the NHI-weighted harmonic mean spin temperature (Ts) at redshifts between z = 0.37 and 1.0. We find that Ts ≤ 274 K with 95 per cent probability, suggesting that at these redshifts the typical H i gas in galaxies at equivalent DLA column densities may be colder than the Milky Way interstellar medium (Ts, MW ∼ 300 K). This result is consistent with an evolving CNM fraction that mirrors the molecular gas towards the peak in SFR at z ∼ 2. We expect that future surveys for H i 21-cm absorption with the current SKA pathfinder telescopes will be able to provide constraints on the CNM fraction that are an order of magnitude greater than presented here.

scholarly journals On the relationship between gas content, star formation, and global H i asymmetry of galaxies on the star-forming main-sequence

2021 ◽  
Vol 504 (2) ◽  
pp. 1989-1998
Author(s):  
Adam B Watts ◽  
Barbara Catinella ◽  
Luca Cortese ◽  
Chris Power ◽  
Sara L Ellison
Keyword(s):  
Star Formation ◽  
Atomic Hydrogen ◽  
Main Sequence ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Gas Content ◽  
Merger Activity ◽  
Star Forming ◽  
The Relationship

ABSTRACT Observations have revealed that disturbances in the cold neutral atomic hydrogen (H i) in galaxies are ubiquitous, but the reasons for these disturbances remain unclear. While some studies suggest that asymmetries in integrated H i spectra (global H i asymmetry) are higher in H i-rich systems, others claim that they are preferentially found in H i-poor galaxies. In this work, we utilize the Arecibo Legacy Fast ALFA (ALFALFA) and extended GALEX Arecibo SDSS Survey (xGASS) surveys, plus a sample of post-merger galaxies, to clarify the link between global H i asymmetry and the gas properties of galaxies. Focusing on star-forming galaxies in ALFALFA, we find that elevated global H i asymmetry is not associated with a change in the H i content of a galaxy, and that only the galaxies with the highest global H i asymmetry show a small increase in specific star formation rate (sSFR). However, we show that the lack of a trend with H i content is because ALFALFA misses the ‘gas-poor’ tail of the star-forming main-sequence. Using xGASS to obtain a sample of star-forming galaxies that is representative in both sSFR and H i content, we find that global H i asymmetric galaxies are typically more gas-poor than symmetric ones at fixed stellar mass, with no change in sSFR. Our results highlight the complexity of the connection between galaxy properties and global H i asymmetry. This is further confirmed by the fact that even post-merger galaxies show both symmetric and asymmetric H i spectra, demonstrating that merger activity does not always lead to an asymmetric global H i spectrum.

scholarly journals Molecular hydrogen in IllustrisTNG galaxies: carefully comparing signatures of environment with local CO & SFR data

2020 ◽  
Author(s):  
Adam R H Stevens ◽  
Claudia del P Lagos ◽  
Luca Cortese ◽  
Barbara Catinella ◽  
Benedikt Diemer ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Star Formation ◽  
Atomic Hydrogen ◽  
Representative Sample ◽  
Molecular Hydrogen ◽  
Quantitative Agreement ◽  
Stellar Mass ◽  
Hydrodynamic Simulation ◽  
Mass Ratios ◽  
Co Emission

Abstract We examine how the post-processed content of molecular hydrogen (H2) in galaxies from the TNG100 cosmological, hydrodynamic simulation changes with environment at z = 0, assessing central/satellite status and host halo mass. We make close comparisons with the carbon monoxide (CO) emission survey xCOLD GASS where possible, having mock-observed TNG100 galaxies to match the survey’s specifications. For a representative sample of host haloes across 1011 ≲ M200c/M⊙ < 1014.6, TNG100 predicts that satellites with m* ≥ 109 M⊙ should have a median deficit in their H2fractions of ∼0.6 dex relative to centrals of the same stellar mass. Once observational and group-finding uncertainties are accounted for, the signature of this deficit decreases to ∼0.2 dex. Remarkably, we calculate a deficit in xCOLD GASS satellites’ H2content relative to centrals of 0.2–0.3 dex, in line with our prediction. We further show that TNG100 and SDSS data exhibit continuous declines in the average star formation rates of galaxies at fixed stellar mass in denser environments, in quantitative agreement with each other. By tracking satellites from their moment of infall in TNG100, we directly show that atomic hydrogen (H i) is depleted at fractionally higher rates than H2on average. Supporting this picture, we find that the H2/H i mass ratios of satellites are elevated relative to centrals in xCOLD GASS. We provide additional predictions for the effect of environment on H2 — both absolute and relative to H i — that can be tested with spectral stacking in future CO surveys.

scholarly journals xGASS: passive discs do not host unexpectedly large reservoirs of cold atomic hydrogen

2020 ◽  
Vol 494 (1) ◽  
pp. L42-L47 ◽  
Author(s):  
L Cortese ◽  
B Catinella ◽  
R H W Cook ◽  
S Janowiecki
Keyword(s):  
Star Formation ◽  
Atomic Hydrogen ◽  
Main Sequence ◽  
Formation Rate ◽  
Large Population ◽  
Mass Range ◽  
Star Forming ◽  
Central Disc ◽  
Upper Limits ◽  
Disc Galaxies

ABSTRACT We use the extended GALEX Arecibo SDSS Survey (xGASS) to quantify the relationship between atomic hydrogen (H i) reservoir and current star formation rate (SFR) for central disc galaxies. This is primarily motivated by recent claims for the existence, in this sample, of a large population of passive discs harbouring H i reservoirs as large as those observed in main-sequence galaxies. Across the stellar mass range 109 < M*/M⊙ < 1011, we practically find no passive (≳2σ below the star forming main sequence) disc galaxies with H i reservoirs comparable to those typical of star-forming systems. Even including H i non-detections at their upper limits, passive discs typically have ≥0.5 dex less H i than their active counterparts. We show that previous claims are due to the use of aperture-corrected SFR estimates from the MPA/JHU SDSS DR7 catalogue, which do not provide a fair representation of the global SFR of H i-rich galaxies with extended star-forming discs. Our findings confirm that the bulk of the passive disc population in the local Universe is H i-poor. These also imply that the reduction of star formation, even in central disc galaxies, has to be accompanied by a reduction in their H i reservoir.

scholarly journals Disc growth and quenching

2019 ◽  
Vol 491 (1) ◽  
pp. L51-L55 ◽  
Author(s):  
Ying-jie Peng ◽  
Alvio Renzini
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Atomic Hydrogen ◽  
Observational Studies ◽  
Radial Flow ◽  
Observational Evidence ◽  
Molecular Gas ◽  
Scaling Relation ◽  
Star Forming ◽  
Large Factor

ABSTRACT Based on well-established scaling relation for star-forming galaxies as a function of redshift, we argue that the implied growth by a large factor of their angular momentum requires that the angular momentum of the inflowing gas fuelling star formation and disc growth must also secularly increase. We then propose that star formation in discs can cease (quench) once the accreted material (mainly atomic hydrogen) comes in with excessive angular momentum for sustaining an adequate radial flow of cold, molecular gas. Existing observational evidence supporting this scenario is mentioned, together with some future observational studies that may validate (or invalidate) it.

scholarly journals Gas-to-Dust Ratios in the Magellanic Clouds

1984 ◽  
Vol 108 ◽  
pp. 333-339 ◽  
Author(s):  
Jan Koornneef
Keyword(s):  
Star Formation ◽  
Spatial Resolution ◽  
Atomic Hydrogen ◽  
Total Mass ◽  
Stellar Population ◽  
Large Fraction ◽  
Magellanic Clouds ◽  
Relative Location ◽  
Optical Photometry ◽  
The Poor

From radio observations it has been known for some time that a relatively large fraction of the total mass of the Magellanic Clouds is in the form of atomic Hydrogen. In contrast, optical photometry shows that both galaxies suffer rather little obscuration by dust, except in regions where the stellar population indicates recent star formation. However, the possibilities of discussing gas-to-dust ratios have been limited by the poor spatial resolution of the 21 cm HI-observations and uncertainties with respect to the relative location of the various components (gas, dust and stars).

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