Cosmic evolution of molecular gas mass density from an empirical relationship between <i>L</i>1.4 GHz and <i>L</i>′CO

Orellana-González, Gustavo; Ibar, E.; Leiton, R.; Thomson, A. P.; Cheng, Cheng; Ivison, R. J.; Herrera-Camus, Rodrigo; Messias, H.; Calderón-Castillo, Paula; Hughes, T. M.; Leeuw, Lerothodi Leonard

doi:10.1093/mnras/staa1171

Cited by 6 publications

(6 citation statements)

References 121 publications

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“…We mark active galaxies with dots, SF galaxies with yellow stars and COMP galaxies with purple stars. We find a good agreement with the empirical correlation found by Orellana-González et al (2020) for L 1.4 GHz and observe a similar behaviour for the SF-COMP subsamples at 3 GHz and 150 MHz. We note that galaxies classified as AGNs do not follow such a linear relation.…”

Section: Co and Radio Luminositysupporting

confidence: 89%

“…2.6.2) for all three radio continuum measurements. We performed a linear fit and find a slightly flatter relation between L CO and L 1.4 GHz in comparison to Orellana-González et al (2020). Furthermore, we find nearly the same slope for L CO -L 150 MHz relation (0.80 ± 0.06), the L CO -L 1.4 GHz relation (0.79 ± 0.04) and the L CO -L 3 GHz relation (0.87 ± 0.07).…”

Section: Co and Radio Luminositysupporting

confidence: 53%

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Central star formation in double-peak gas rich radio galaxies

Maschmann,

Melchior,

Combes

et al. 2021

Preprint

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The respective contributions of gas accretion, galaxy interactions, and mergers to the mass assembly of galaxies, their morphological transformations, and the changes in their molecular gas content and star formation activity are still not fully understood. Galaxies with two kinematic components which are manifested as a double-peak (DP) in their emission lines, have been identified in a recent work to play a major role in the morphological transformation towards larger bulges. Notably, star-forming DP galaxies display a central star formation enhancement and are thought to be associated to a sequence of recent minor mergers. In order to probe merger induced star formation mechanisms, we conducted observations of the molecular gas content of star-forming DP galaxies in the upper part of the main sequence (MS) of star formation with the IRAM 30m telescope. In combination with existing molecular gas observations from the literature, we gathered a sample of 41 such galaxies. We succeed to fit the same kinematic parameters to the optical ionised and molecular gas emission lines for 24 (59 %) galaxies. We find a central star formation enhancement which is most likely the result of a galaxy merger or galaxy interactions which is indicated by an excess of gas extinction found in the centre. This star formation is traced by radio continuum emissions of 150 MHz, 1.4 GHz and 3 GHz, which are all three linearly correlated with the CO luminosity described by the same slope. By comparing the measured star formation efficiency and the molecular gas mass fraction with the expected values of the MS, we find a significantly larger amount of molecular gas in the present DP galaxies and larger depletion times. We discard a scenario of large scale instabilities driving gas into the centre and find no direct link between the measured kinematic signatures and inclination. This leads us to conclude that the observed DP galaxies are mostly the result of a recent merger that funnelled molecular gas towards the centre, triggering efficient star formation there.

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Section: Co and Radio Luminositysupporting

confidence: 89%

Section: Co and Radio Luminositysupporting

confidence: 53%

Central star formation in double-peak gas rich radio galaxies

Maschmann,

Melchior,

Combes

et al. 2021

Preprint

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“…3.3.1) for all three radio-continuum measurements. We performed a linear fit and find a slightly flatter relation between L CO and L 1.4 GHz than Orellana-González et al (2020). Furthermore, we find nearly the same slope for the L CO −L 150 MHz relation (0.80 ± 0.06), the L CO −L 1.4 GHz relation (0.79 ± 0.04), and the L CO −L 3 GHz relation (0.87 ± 0.07).…”

Section: Star-formation Dominated Galaxiessupporting

confidence: 50%

Central star formation in double-peak, gas-rich radio galaxies

Maschmann

Melchior

Combes

et al. 2022

A&A

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The respective contributions of gas accretion, galaxy interactions, and mergers to the mass assembly of galaxies, as well as the evolution of their molecular gas and star-formation activity are still not fully understood. In a recent work, a large sample of double-peak (DP) emission-line galaxies have been identified from the SDSS. While the two peaks could represent two kinematic components, they may be linked to the large bulges that their host galaxies tend to have. Star-forming DP galaxies display a central star-formation enhancement and have been discussed as compatible with a sequence of recent minor mergers. In order to probe merger-induced star-formation mechanisms, we conducted observations of the molecular-gas content of 35 star-forming DP galaxies in the upper part of the main sequence (MS) of star formation (SF) with the IRAM 30 m telescope. Including similar galaxies 0.3 dex above the MS and with existing molecular-gas observations from the literature, we finally obtained a sample of 52 such galaxies. We succeeded in fitting the same kinematic parameters to the optical ionised- and molecular-gas emission lines for ten (19%) galaxies. We find a central star-formation enhancement resulting most likely from a galaxy merger or galaxy interaction, which is indicated by an excess of gas extinction found in the centre. This SF is traced by radio continuum emissions at 150 MHz, 1.4 GHz, and 3 GHz, all three of which are linearly correlated in log with the CO luminosity with the same slope. The 52 DP galaxies are found to have a significantly larger amount of molecular gas and longer depletion times, and hence a lower star-formation efficiency, than the expected values at their distance of the MS. The large bulges in these galaxies might be stabilising the gas, hence reducing the SF efficiency. This is consistent with a scenario of minor mergers increasing the mass of bulges and driving gas to the centre. We also excluded the inwards-directed gas migration and central star-formation enhancement as the origin of a bar morphology. Hence, these 52 DP galaxies could be the result of recent minor mergers that funnelled molecular gas towards their centre, triggering SF, but with moderate efficiency.

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“…12 compares our model CO(1-0) LFs with those converted from the ASPECS data. We also plot the observational results of Orellana-González et al (2020) which include brighter galaxies than ASPECS. 7 Our model matches the observed CO-LFs within the error ranges at z 2.0.…”

Section: Comparison With Aspecsmentioning

confidence: 99%

“…Orellana-González et al (2020) estimate the CO-LFs for their compilation of various observations using correlations between the luminosities of radio continuum, infrared and CO emission.8 Orellana-González et al (2020) also assume α CO = 3.6.…”

mentioning

confidence: 99%

The CO universe: Modelling CO emission and H$_{\rm 2}$ abundance in cosmological galaxy formation simulations

Inoue,

Yoshida,

Yajima

2020

Preprint

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We devise a physical model of formation and distribution of molecular gas clouds in galaxies. We use the model to predict the intensities of rotational transition lines of carbon monoxide (CO) and the molecular hydrogen (H 2 ) abundance. Using the outputs of Illustris-TNG cosmological simulations, we populate molecular gas clouds of unresolved sizes in individual simulated galaxies, where the effect of the interstellar radiation field with dust attenuation is also taken into account. We then use the publicly available code DESPOTIC to compute the CO line luminosities and H 2 densities without assuming the CO-to-H 2 conversion factor (α CO ). Our method allows us to study the spatial and kinematic structures traced by CO(1-0) and higher transition lines. We compare the CO luminosities and H 2 masses with recent observations of galaxies at low and high redshifts. Our model reproduces well the observed CO-luminosity function and the estimated H 2 mass in the local Universe. About ten percent of molecules in the Universe reside in dwarf galaxies with stellar masses lower than 10 9 M , but the galaxies are generally 'CO-dark' and have typically high α CO . Our model predicts generally lower CO line luminosities than observations at redshifts z 1-2. We argue that the difference can be explained by the highly turbulent structure suggested for the high-redshift star-forming galaxies.

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Cosmic evolution of molecular gas mass density from an empirical relationship between L1.4 GHz and L′CO

Cited by 6 publications

References 121 publications

Central star formation in double-peak gas rich radio galaxies

Central star formation in double-peak gas rich radio galaxies

Central star formation in double-peak, gas-rich radio galaxies

The CO universe: Modelling CO emission and H$_{\rm 2}$ abundance in cosmological galaxy formation simulations

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