Strong Far-ultraviolet Fields Drive the [C ii]/Far-infrared Deficit inz∼ 3 Dusty, Star-forming Galaxies

ABSTRACT We combine the shark semi-analytic model of galaxy formation with the prospect software tool for spectral energy distribution (SED) generation to study the multiwavelength emission of galaxies from the far-ultraviolet (FUV) to the far-infrared (FIR) at 0 ≤ z ≤ 10. We produce a physical model for the attenuation of galaxies across cosmic time by combining a local Universe empirical relation to compute the dust mass of galaxies from their gas metallicity and mass, attenuation curves derived from radiative transfer calculations of galaxies in the eagle hydrodynamic simulation suite, and the properties of shark galaxies. We are able to produce a wide range of galaxies, from the z = 8 star-forming galaxies with almost no extinction, z = 2 submillimetre galaxies, down to the normal star-forming and red-sequence galaxies at z = 0. Quantitatively, we find that shark reproduces the observed (i) z = 0 FUV-to-FIR, (ii) 0 ≤ z ≤ 3 rest-frame K-band, and (iii) 0 ≤ z ≤ 10 rest-frame FUV luminosity functions, (iv) z ≤ 8 UV slopes, (v) the FUV-to-FIR number counts (including the widely disputed 850 μm), (vi) redshift distribution of bright $850\, \mu$m galaxies, and (vii) the integrated cosmic SED from z = 0 to 1 to an unprecedented level. This is achieved without the need to invoke changes in the stellar initial mass function, dust-to-metal mass ratio, or metal enrichment time-scales. Our model predicts star formation in galaxy discs to dominate in the FUV-to-optical, while bulges dominate at the NIR at all redshifts. The FIR sees a strong evolution in which discs dominate at z ≤ 1 and starbursts (triggered by both galaxy mergers and disc instabilities, in an even mix) dominate at higher redshifts, even out to z = 10.

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Narrow-band Hα imaging of nearby Wolf–Rayet galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2833 ◽

2019 ◽

Vol 490 (3) ◽

pp. 3448-3453

Author(s):

A Paswan ◽

Kanak Saha ◽

A Omar

Keyword(s):

Star Formation ◽

Main Sequence ◽

Narrow Band ◽

Far Infrared ◽

Infrared Excess ◽

Nearby Star ◽

Star Forming ◽

Star Forming Regions ◽

Far Ultraviolet ◽

First Time

ABSTRACT We present narrow-band Hα imaging of nearby Wolf–Rayet (WR) galaxies known as a subset of starburst galaxies. The Hα images have been used to show morphology of star-forming regions in galaxies, which leads to speculate that the studied galaxies have most likely experienced merger or interaction with low luminous dwarf galaxies or H i clouds. We further derive the Hα-based star formation rates (SFRs) in galaxies using our Hα observations. These SFRs are well correlated with SFRs derived using other indicators at far-ultraviolet, far-infrared, and 1.4-GHz radio wavebands. It is noticed that the infrared excess (IRX) method gives the best SFR estimates, consistent with different models predication. These models also predict that the sample galaxies have probably gone through a continuous star formation at least for 1 Gyr over which the recent (<10 Myr) star formation has taken place in WR phase. This study presents main-sequence (MS) relation for nearby WR galaxies for the first time. This derived MS relation is found to be similar to previously known MS relation for normal nearby star-forming galaxies, suggesting that WR systems evolve in a similar fashion as normal star-forming galaxies evolve.

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Full of Orions: a 200-pc mapping of the interstellar medium in the redshift-3 lensed dusty star-forming galaxy SDP.81

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa879 ◽

2020 ◽

Vol 494 (4) ◽

pp. 5542-5567 ◽

Cited By ~ 2

Author(s):

Matus Rybak ◽

J A Hodge ◽

S Vegetti ◽

P van der Werf ◽

P Andreani ◽

...

Keyword(s):

Field Strength ◽

Interstellar Medium ◽

Far Infrared ◽

Source Plane ◽

Star Forming ◽

Physical Conditions ◽

Orion Trapezium ◽

Thermal Saturation ◽

Continuum Data ◽

Far Ultraviolet

ABSTRACT We present a sub-kpc resolved study of the interstellar medium properties in SDP.81, a $z$ = 3.042 strongly gravitationally lensed, dusty star-forming galaxy, based on high-resolution, multiband ALMA observations of the far-infrared (FIR) continuum, CO ladder, and the [C ii] line. Using a visibility-plane lens modelling code, we achieve a median source-plane resolution of ∼200 pc. We use photon-dominated region (PDR) models to infer the physical conditions – far-ultraviolet (FUV) field strength, density, and PDR surface temperature – of the star-forming gas on 200-pc scales, finding a FUV field strength of ∼103−104G0, gas density of ∼105 cm−3, and cloud surface temperatures up to 1500 K, similar to those in the Orion Trapezium region. The [C ii] emission is significantly more extended than that FIR continuum: ∼50 per cent of [C ii] emission arises outside the FIR-bright region. The resolved [C ii]/FIR ratio varies by almost 2 dex across the source, down to ∼2 × 10−4 in the star-forming clumps. The observed [C ii]/FIR deficit trend is consistent with thermal saturation of the C+ fine-structure-level occupancy at high gas temperatures. We make the source-plane reconstructions of all emission lines and continuum data publicly available.

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Predictions for the spatial distribution of the dust continuum emission in $\boldsymbol {1\,\lt\, z\,\lt\, 5}$ star-forming galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1736 ◽

2019 ◽

Vol 488 (2) ◽

pp. 1779-1789 ◽

Cited By ~ 14

Author(s):

R K Cochrane ◽

C C Hayward ◽

D Anglés-Alcázar ◽

J Lotz ◽

T Parsotan ◽

...

Keyword(s):

Star Formation ◽

Formation Rate ◽

Dust Emission ◽

Far Infrared ◽

Continuum Emission ◽

Spectral Energy ◽

Star Forming ◽

Dust Mass ◽

Far Ultraviolet ◽

Stellar Masses

ABSTRACT We present the first detailed study of the spatially resolved dust continuum emission of simulated galaxies at 1 < z < 5. We run the radiative transfer code skirt on a sample of submillimetre-bright galaxies drawn from the Feedback In Realistic Environments (FIRE) project. These simulated galaxies reach Milky Way masses by z = 2. Our modelling provides predictions for the full rest-frame far-ultraviolet-to-far-infrared spectral energy distributions of these simulated galaxies, as well as 25-pc resolution maps of their emission across the wavelength spectrum. The derived morphologies are notably different in different wavebands, with the same galaxy often appearing clumpy and extended in the far-ultraviolet yet an ordered spiral at far-infrared wavelengths. The observed-frame 870-$\mu$m half-light radii of our FIRE-2 galaxies are ${\sim} 0.5\rm {-}4\, \rm {kpc}$, consistent with existing ALMA observations of galaxies with similarly high redshifts and stellar masses. In both simulated and observed galaxies, the dust continuum emission is generally more compact than the cold gas and the dust mass, but more extended than the stellar component. The most extreme cases of compact dust emission seem to be driven by particularly compact recent star formation, which generates steep dust temperature gradients. Our results confirm that the spatial extent of the dust continuum emission is sensitive to both the dust mass and star formation rate distributions.

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Resolving distant, dusty galaxies using observations and simulations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319008998 ◽

2019 ◽

Vol 15 (S352) ◽

pp. 282-286

Author(s):

R. K. Cochrane

Keyword(s):

Rest Frame ◽

High Redshift ◽

Far Infrared ◽

Small Sample ◽

Star Forming ◽

Spatially Resolved ◽

Dusty Galaxies ◽

Wavelength Emission ◽

Hydrodynamical Simulations ◽

Far Ultraviolet

AbstractSpatially resolved studies of galaxies in the high-redshift Universe have traditionally been reliant on data at rest-frame optical and UV wavelengths, which can be biased towards the least dust-obscured galaxies. For several years now, we have been able to resolve and probe the morphology of longer-wavelength emission from distant galaxies with ALMA, and a number of recent ALMA studies were presented at the IAU Symposium No. 352. These included our study of the resolved multi-wavelength emission of galaxies at z ∼ 2. As part of the SHiZELS collaboration, we are mapping the Hα emission line (from SINFONI/VLT), UV continuum (from HST), and the far-infrared (from ALMA) emission from a small sample of Hα-selected galaxies. In this proceedings paper, we showcase the high quality of our data, and the spectacular structures displayed by one of our most dusty sources. We also provide an overview of some highly complementary simulation-based work, using galaxies drawn from the FIRE-2 zoom-in cosmological hydrodynamical simulations. Using sophisticated radiative transfer techniques, we have derived predictions for the spatially-resolved emission of a sample of star-forming galaxies, from rest-frame far-ultraviolet to the far-infrared. For both observed and simulated galaxies, emission maps show striking differences with wavelength, with the same galaxy appearing clumpy and extended in the far-ultraviolet yet compact at far-infrared wavelengths.

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Far infrared study of the giant star forming complex W 51

EAS Publications Series ◽

10.1051/eas:2002097 ◽

2002 ◽

Vol 4 ◽

pp. 333-333

Author(s):

S. K. Ghosh ◽

D. K. Ojha ◽

R. P. Verma

Keyword(s):

Far Infrared ◽

Infrared Study ◽

Giant Star ◽

Star Forming

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Tracing young SMBHs in the dusty distant universe – a Chandra view of DOGs

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320004032 ◽

2020 ◽

Vol 15 (S359) ◽

pp. 17-21

Author(s):

Karín Menéndez-Delmestre ◽

Laurie Riguccini ◽

Ezequiel Treister

Keyword(s):

Star Formation ◽

Main Sequence ◽

Far Infrared ◽

Host Galaxy ◽

X Ray ◽

Star Forming ◽

Near Ir ◽

X Ray Imaging ◽

Combined Use ◽

Dusty Galaxies

AbstractThe coexistence of star formation and AGN activity has geared much attention to dusty galaxies at high redshifts, in the interest of understanding the origin of the Magorrian relation observed locally, where the mass of the stellar bulk in a galaxy appears to be tied to the mass of the underlying supermassive black hole. We exploit the combined use of far-infrared (IR) Herschel data and deep Chandra ˜160 ksec depth X-ray imaging of the COSMOS field to probe for AGN signatures in a large sample of >100 Dust-Obscured Galaxies (DOGs). Only a handful (˜20%) present individual X-ray detections pointing to the presence of significant AGN activity, while X-ray stacking analysis on the X-ray undetected DOGs points to a mix between AGN activity and star formation. Together, they are typically found on the main sequence of star-forming galaxies or below it, suggesting that they are either still undergoing significant build up of the stellar bulk or have started quenching. We find only ˜30% (6) Compton-thick AGN candidates (NH > 1024 cm–2), which is the same frequency found within other soft- and hard-X-ray selected AGN populations. This suggests that the large column densities responsible for the obscuration in Compton-thick AGNs must be nuclear and have little to do with the dust obscuration of the host galaxy. We find that DOGs identified to have an AGN share similar near-IR and mid-to-far-IR colors, independently of whether they are individually detected or not in the X-ray. The main difference between the X-ray detected and the X-ray undetected populations appears to be in their redshift distributions, with the X-ray undetected ones being typically found at larger distances. This strongly underlines the critical need for multiwavelength studies in order to obtain a more complete census of the obscured AGN population out to higher redshifts. For more details, we refer the reader to Riguccini et al. (2019).

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Reproducing the Universe: a comparison between the EAGLE simulations and the nearby DustPedia galaxy sample

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa857 ◽

2020 ◽

Vol 494 (2) ◽

pp. 2823-2838 ◽

Cited By ~ 4

Author(s):

Ana Trčka ◽

Maarten Baes ◽

Peter Camps ◽

Sharon E Meidt ◽

James Trayford ◽

...

Keyword(s):

Radiative Transfer ◽

Physical Properties ◽

Numerical Models ◽

Far Infrared ◽

Spectral Energy ◽

Star Forming ◽

Star Forming Regions ◽

Global Emission ◽

Galaxy Sample ◽

Galaxy Population

ABSTRACT We compare the spectral energy distributions (SEDs) and inferred physical properties for simulated and observed galaxies at low redshift. We exploit UV-submillimetre mock fluxes of ∼7000 z = 0 galaxies from the EAGLE suite of cosmological simulations, derived using the radiative transfer code skirt. We compare these to ∼800 observed galaxies in the UV-submillimetre range, from the DustPedia sample of nearby galaxies. To derive global properties, we apply the SED fitting code cigale consistently to both data sets, using the same set of ∼80 million models. The results of this comparison reveal overall agreement between the simulations and observations, both in the SEDs and in the derived physical properties, with a number of discrepancies. The optical and far-infrared regimes, and the scaling relations based upon the global emission, diffuse dust, and stellar mass, show high levels of agreement. However, the mid-infrared fluxes of the EAGLE galaxies are overestimated while the far-UV domain is not attenuated enough, compared to the observations. We attribute these discrepancies to a combination of galaxy population differences between the samples and limitations in the subgrid treatment of star-forming regions in the EAGLE-skirt post-processing recipe. Our findings show the importance of detailed radiative transfer calculations and consistent comparison, and provide suggestions for improved numerical models.

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Towards a census of high-redshift dusty galaxies with Herschel

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731888 ◽

2018 ◽

Vol 614 ◽

pp. A33 ◽

Cited By ~ 9

Author(s):

D. Donevski ◽

V. Buat ◽

F. Boone ◽

C. Pappalardo ◽

M. Bethermin ◽

...

Keyword(s):

Galaxy Evolution ◽

High Redshift ◽

Spectral Energy Distribution ◽

Formation Rate ◽

Far Infrared ◽

Virgo Cluster ◽

Spectral Energy ◽

Distribution Fitting ◽

Redshift Distribution ◽

Star Forming

Context. Over the last decade a large number of dusty star-forming galaxies has been discovered up to redshift z = 2 − 3 and recent studies have attempted to push the highly confused Herschel SPIRE surveys beyond that distance. To search for z ≥ 4 galaxies they often consider the sources with fluxes rising from 250 μm to 500 μm (so-called “500 μm-risers”). Herschel surveys offer a unique opportunity to efficiently select a large number of these rare objects, and thus gain insight into the prodigious star-forming activity that takes place in the very distant Universe. Aims. We aim to implement a novel method to obtain a statistical sample of 500 μm-risers and fully evaluate our selection inspecting different models of galaxy evolution. Methods. We consider one of the largest and deepest Herschel surveys, the Herschel Virgo Cluster Survey. We develop a novel selection algorithm which links the source extraction and spectral energy distribution fitting. To fully quantify selection biases we make end-to-end simulations including clustering and lensing. Results. We select 133 500 μm-risers over 55 deg2, imposing the criteria: S500 > S350 > S250, S250 > 13.2 mJy and S500 > 30 mJy. Differential number counts are in fairly good agreement with models, displaying a better match than other existing samples. The estimated fraction of strongly lensed sources is 24+6-5% based on models. Conclusions. We present the faintest sample of 500 μm-risers down to S250 = 13.2 mJy. We show that noise and strong lensing have an important impact on measured counts and redshift distribution of selected sources. We estimate the flux-corrected star formation rate density at 4 < z < 5 with the 500 μm-risers and find it to be close to the total value measured in far-infrared. This indicates that colour selection is not a limiting effect to search for the most massive, dusty z > 4 sources.

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Far-Infrared Emission from Clumpy Irregular Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900096728 ◽

1987 ◽

Vol 115 ◽

pp. 647-647

Author(s):

U. Klein ◽

J. Heidmann ◽

R. Wielebinski ◽

E. Wunderlich

Keyword(s):

Star Formation ◽

Star Formation Rate ◽

Formation Rate ◽

Hubble Constant ◽

Far Infrared ◽

Hii Regions ◽

Infrared Emission ◽

Star Forming ◽

Irregular Galaxies

The four clumpy irregular galaxies Mkr 8, 296,297 and 325 have been observed by IRAS. All galaxies have been detected in at least two of the four detector bands. The ratios of the 100 to 60-m flux densities are comparable to those of HII regions or violently star forming galaxies. The average star formation rate in clumpy irregular galaxies is of the order of a few solar masses per year (based on their average far-infrared luminosity and a Hubble constant of 75 km s−1 Mpc−1.

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