Aims. The main aim of this work is the characterization of physical properties of galaxies detected in the far-infrared (FIR) in the AKARI Deep Field-South (ADF-S) survey. Methods. Starting from a ...catalog of the 1000 brightest ADF-S sources in the WIDE-S (90 μm) AKARI band, we constructed a subsample of galaxies with spectral coverage from the ultraviolet to the FIR. We then analyzed the multiwavelength properties of this 90 μm selected sample of galaxies. For galaxies without known spectroscopic redshifts we computed photometric redshifts using the codes Photometric Analysis for Redshift Estimate (Le PHARE) and Code Investigating GALaxy Emission (CIGALE), tested these photometric redshifts using spectroscopic redshifts, and compared the performances of both codes. To test the reliability of parameters obtained by fitting spectral energy distributions, a mock catalogue was generated. Results. We built a large multiwavelength catalog of more than 500 ADF-S galaxies. We successfully fitted spectral energy distributions of 186 galaxies with \hbox{$\chi^2_{\rm min}<4$}χmin2<4, and analyzed the output parameters of the fits. We conclude that our sample consists mostly of nearby actively star-forming galaxies, and all our galaxies have a relatively high metallicity. We estimated photometric redshifts for 113 galaxies from the whole ADF-S sample. Comparing the performance of Le PHARE and CIGALE, we found that CIGALE gives more reliable redshift estimates for our galaxies, which implies that including the IR photometry allows for substantial improvement of photometric redshift estimation.
The effect of active galactic nuclei (AGN) on their host galaxies – in particular their levels of star formation – remains one of the key outstanding questions of galaxy evolution. Successful ...cosmological models of galaxy evolution require a fraction of energy released by an AGN to be redistributed into the interstellar medium to reproduce the observed stellar mass and luminosity function and to prevent the formation of over-massive galaxies. Observations have confirmed that the radio-AGN population is energetically capable of heating and redistributing gas at all phases, however, direct evidence of AGN enhancing or quenching star formation remains rare. With modern, deep radio surveys and large integral field spectroscopy (IFS) surveys, we can detect fainter synchrotron emission from AGN jets and accurately probe the star-forming properties of galaxies, respectively. In this paper, we combine data from the LOw Frequency ARray Two-meter Sky Survey (LoTSS) with data from one of the largest optical IFS surveys, Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), to probe the star-forming properties of 307 local (
z
< 0.15) galaxies that host radio-detected AGN (RDAGN). We compare our results to a robust control sample of non-active galaxies that each match the stellar mass, redshift, visual morphology, and inclination of a RDAGN host. We find that RDAGN and control galaxies have broad star-formation rate (SFR) distributions, typically lie below the SFMS, and have negative stellar light-weighted age gradients. These results indicate that AGN selected based on their current activity are not responsible for suppressing their host galaxies’ star formation. Rather, our results support the maintenance mode role that radio AGN are expected to have in the local Universe.
Context.
Hyper-luminous infrared galaxies (HLIRGs) are among the most extreme systems in the Universe. With infrared (IR) luminosities of
L
IR
> 10
13
L
⊙
they can have IR-derived star formation ...rates (SFRs) exceeding 10
3
M
⊙
yr
−1
. Theoretical models have a hard time reproducing the observed number densities of such extreme star-forming systems. It is known that at least part of the population harbours active galactic nuclei (AGNs), but their prevalence and relative contribution to the IR output is still debated. Assessing this is further complicated by the heavy dust obscuration.
Aims.
We aim to investigate the HLIRG population in the Lockman Hole field to assess whether they are truly highly star-bursting systems or whether notable AGN activity is present. A substantial AGN population could help resolve the tension between the HLIRG number densities obtained from observations and predicted by galaxy formation models by lowering the amount of truly extremely star-forming galaxies.
Methods.
Starting from a highly complete
Herschel
-selected sample, we made use of recent wide-field sub-arcsecond 144 MHz International LOFAR Telescope (ILT) observations of the Lockman Hole field to probe AGN activity in HLIRGs in a dust-unobscured way. AGN presence was deduced through means of the brightness temperature (
T
b
). Brightness temperature measurements were made to determine the fraction of HLIRGs harbouring a radio AGN. This identification was then compared to the classification based on spectral energy distribution (SED) fitting based identification from the LOFAR Deep Fields project, the radio-excess
q
and IRAC infrared colours.
Results.
We detect 33% of previously identified HLIRGs at sub-arcsecond resolution. All but one of the detected sources is found to exceed the
T
b
threshold for pure star formation, showing 98% of detections to contain a radio AGN, even though lower-resolution observations had classified them as star-forming galaxies (SFGs). The remaining source is concluded to be consistent with having no AGN activity. All of the sources in our sample that were previously classified as radio AGNs, radio-quiet AGNs or those that were unclassified were detected as high-
T
b
objects (16% of the total sample or 47% of the detected sub-arcsecond detections). In addition, we identify AGNs through
T
b
measurements in 20% of sources that were classified as SFGs through SED fitting, raising the overall fraction of AGNs in the total sample from 16% to 32%. AGNs identified through brightness temperature measurements are also found to be more likely to be mid-IR AGNs.
Conclusions.
98% of our detected sources are found to likely host radio-AGNs, raising the number of identified AGNs among the HLIRG population in this field from 16% to 32%. This increased number of AGNs is not sufficient to bring observations and predictions of HLIRG number densities in agreement, however. Even at cosmic noon around
z
∼ 2, where the tension is lowest, it remains at a factor of just a few. The identification of radio AGNs in supposed SFGs highlights the value of high-resolution radio observations in studying dusty objects such as HLIRGs. Broad consistency is seen between
T
b
and the other AGN indicators, and the observed relation between SFR and
T
b
is seen as indicative of co-evolution between stellar mass build-up and black hole growth.
We exploit the first public data release of VIPERS to investigate environmental effects in the evolution of galaxies between z ~ 0.5 and 0.9. The large number of spectroscopic redshifts (more than 50 ...000) over an area of about 10 deg2 provides a galaxy sample with high statistical power. We estimate the stellar mass function of galaxies residing in these two environments and constrain the high-mass end with unprecedented precision. We observe an evolution of the stellar mass function of VIPERS galaxies in high densities, while the low-density one is nearly constant. We compare these results to semi-analytical models and find consistent environmental signatures in the simulated stellar mass functions. We discuss how the halo mass function and fraction of central/satellite galaxies depend on the environments considered, making intrinsic and environmental properties of galaxies physically coupled, hence difficult to disentangle. The same formalism could also describe the evolution of the mass function in the high density regions, but only if a significant contribution from dry mergers is considered.
Context.
Dusty high-
z
galaxies are extreme objects with high star formation rates (SFRs) and luminosities. Characterising the properties of this population and analysing their evolution over cosmic ...time is key to understanding galaxy evolution in the early Universe.
Aims.
We select a sample of high-
z
dusty star-forming galaxies (DSFGs) and evaluate their position on the main sequence (MS) of star-forming galaxies, the well-known correlation between stellar mass and SFR. We aim to understand the causes of their high star formation and quantify the percentage of DSFGs that lie above the MS.
Methods.
We adopted a multi-wavelength approach with data from optical to submillimetre wavelengths from surveys at the North Ecliptic Pole to study a submillimetre sample of high-redshift galaxies. Two submillimetre selection methods were used, including: sources selected at 850
μ
m with the Sub-millimetre Common-User Bolometer Array 2) SCUBA-2 instrument and
Herschel
-Spectral and Photometric Imaging Receiver (SPIRE) selected sources (colour-colour diagrams and 500
μ
m risers), finding that 185 have good multi-wavelength coverage. The resulting sample of 185 high-
z
candidates was further studied by spectral energy distribution fitting with the CIGALE fitting code. We derived photometric redshifts, stellar masses, SFRs, and additional physical parameters, such as the infrared luminosity and active galactic nuclei (AGN) contribution.
Results.
We find that the
Herschel
-SPIRE selected DSFGs generally have higher redshifts (z = 2.57
−0.09
+0.08
) than sources that are selected solely by the SCUBA-2 method (z = 1.45
−0.06
+0.21
). We find moderate SFRs (797
−50
+108
M
⊙
yr
−1
), which are typically lower than those found in other studies. We find that the different results in the literature are, only in part, due to selection effects, as even in the most extreme cases, SFRs are still lower than a few thousand solar masses per year. The difference in measured SFRs affects the position of DSFGs on the MS of galaxies; most of the DSFGs lie on the MS (60%). Finally, we find that the star formation efficiency (SFE) depends on the epoch and intensity of the star formation burst in the galaxy; the later the burst, the more intense the star formation. We discuss whether the higher SFEs in DSFGs could be due to mergers.
Dust attenuation shapes the spectral energy distribution of galaxies. It is particularly true for dusty galaxies in which stars experience a heavy attenuation. The combination of UV-to-IR photometry ...with the spectroscopic measurement of the H$\alpha$ recombination line helps to quantify dust attenuation of the whole stellar population and its wavelength dependence. We selected an IR complete sample of galaxies in the COSMOS 3D-HST CANDELS field detected with the Herschel satellite with a signal to noise ratio larger than five. Optical to NIR photometry is available as well as NIR spectroscopy for each source. We reduced the sample to the redshift range $0.6 < z < 1.6$ to include the H$\alpha$ line in the G141 grism spectra. We have used a new version of the CIGALE code to fit simultaneously the continuum and H$\alpha$ line emission of the 34 selected galaxies. Using flexible attenuation laws with free parameters, we are able to measure the shape of the attenuation curve for each galaxy as well as the amount of attenuation of each stellar population, the former being in general steeper than the starburst law in the UV-optical with a large variation of the slope among galaxies. The attenuation of young stars or nebular continuum is found on average about twice the attenuation affecting older stars, again with a large variation. Our model with power-laws, based on a modification of the Charlot and Fall recipe, gives results in better agreement with the radiative transfer models than the global modification of the slope of the Calzetti law.
We investigate the dependence of galaxy clustering on luminosity and stellar mass in the redshift range 0.5 < z <1.1, using the first ~55 000 redshifts from the VIMOS Public Extragalactic Redshift ...Survey (VIPERS). We provide the best-fit parameters of the power-law model assumed for the real-space 2PCF - the correlation length, rsub 0, and the slope, gamma - as well as the linear bias parameter, as a function of the B-band absolute magnitude, stellar mass, and redshift. We confirm and provide the tightest constraints on the dependence of clustering on luminosity at 0.5 < z <1.1. We prove the complexity of comparing the clustering dependence on stellar mass from samples that are originally flux-limited and discuss the possible origin of the observed discrepancies. Overall, our measurements provide stronger constraints on galaxy formation models, which are now required to match, in addition to local observations, the clustering evolution measured by VIPERS galaxies between z = 0.5 and z = 1.1 for a broad range of luminosities and stellar masses.
We measure the evolution of the galaxy stellar mass function from z = 1.3W z = 0.5 using the first 53 608 redshifts of the ongoing VIMOS Public Extragalactic Survey (VIPERS). Thanks to its large ...volume and depth, VIPERS provides a detailed picture of the galaxy distribution at z approx = 0.8, when the Universe Was approx =7 Gyr old. We carefully estimate the uncertainties and systematic effects associated with the SED fitting procedure used the derive galaxy stellar masses. We estimate the galaxy stellar mass function at several epochs Stween z = 0.5 and 1.3, discussing the amount of cosmic variance affecting our estimate in detail. We find that for such high masses, red galaxies show a milder evolution with redshift, when compared the objects at lower masses. At the same time, we detect a population of similarly massive blue galaxies, which are no longer detectable below z = 0.7. These results show the improved statistical power of VIPERS data, and give initial promising indications of mass-dependent quenching of galaxies at z approx = 1.
Aims. Large future sky surveys, such as the Legacy Survey of Space and Time (LSST), will provide optical photometry for billions of objects. Reliable estimation of the physical properties of galaxies ...requires information about dust attenuation, which is usually derived from ultraviolet (UV) and infrared (IR) data. This paper aims to construct a proxy for the far-UV (FUV) attenuation (AFUVp) from the optical data alone, enabling the rapid estimation of the star formation rate (SFR) for galaxies that lack UV or IR data. This will accelerate and improve the estimation of key physical properties of billions of LSST–like observed galaxies (observed in the optical bands only). Methods. To mimic LSST observations, we used the deep panchromatic optical coverage of the Sloan Digital Sky Survey (SDSS) Photometric Catalogue, Data Release 12, complemented by the estimated physical properties for the SDSS galaxies from the GALEX-SDSS-WISE Legacy Catalog (GSWLC) and inclination information obtained from the SDSS Data Release 7. We restricted our sample to the 0.025–0.1 spectroscopic redshift range and investigated relations among surface brightness, colours, and dust attenuation in the FUV range for star-forming galaxies obtained from the spectral energy distribution (SED). Results. Dust attenuation is best correlated with colour measured between u and r bands (u − r) and the surface brightness in the u band (μu). We provide a dust attenuation proxy for galaxies on the star-forming main sequence. This relation can be used for the LSST or any other type of broadband optical survey. The mean ratio between the catalogue values of SFRs and those estimated using optical-only SDSS data with the AFUVp prior calculated as ΔSFR = log(SFRthis work/SFRGSWLC) is found to be less than 0.1 dex, while runs without priors result in an SFR overestimation larger than 0.3 dex. The presence or absence of the AFUVp has a negligible influence on the stellar mass (Mstar) estimation (with ΔMstar in the range from 0 to −0.15 dex). Conclusions. We note that AFUVp is reliable for low-redshift main sequence galaxies. Forthcoming deep optical observations of the LSST Deep Drilling Fields, which also have multi-wavelength data, will enable one to calibrate the obtained relation for higher redshift galaxies and, possibly, extend the study towards other types of galaxies, such as early-type galaxies off the main sequence.
Context. Dusty high-z galaxies are extreme objects with high star formation rates (SFRs) and luminosities. Characterising the properties of this population and analysing their evolution over cosmic ...time is key to understanding galaxy evolution in the early Universe. Aims. We select a sample of high-z dusty star-forming galaxies (DSFGs) and evaluate their position on the main sequence (MS) of star-forming galaxies, the well-known correlation between stellar mass and SFR. We aim to understand the causes of their high star formation and quantify the percentage of DSFGs that lie above the MS. Methods. We adopted a multi-wavelength approach with data from optical to submillimetre wavelengths from surveys at the North Ecliptic Pole to study a submillimetre sample of high-redshift galaxies. Two submillimetre selection methods were used, including: sources selected at 850 μm with the Sub-millimetre Common-User Bolometer Array 2) SCUBA-2 instrument and Herschel-Spectral and Photometric Imaging Receiver (SPIRE) selected sources (colour-colour diagrams and 500 μm risers), finding that 185 have good multi-wavelength coverage. The resulting sample of 185 high-z candidates was further studied by spectral energy distribution fitting with the CIGALE fitting code. We derived photometric redshifts, stellar masses, SFRs, and additional physical parameters, such as the infrared luminosity and active galactic nuclei (AGN) contribution. Results. We find that the Herschel-SPIRE selected DSFGs generally have higher redshifts (z = 2.57−0.09+0.08) than sources that are selected solely by the SCUBA-2 method (z = 1.45−0.06+0.21). We find moderate SFRs (797−50+108 M⊙ yr−1), which are typically lower than those found in other studies. We find that the different results in the literature are, only in part, due to selection effects, as even in the most extreme cases, SFRs are still lower than a few thousand solar masses per year. The difference in measured SFRs affects the position of DSFGs on the MS of galaxies; most of the DSFGs lie on the MS (60%). Finally, we find that the star formation efficiency (SFE) depends on the epoch and intensity of the star formation burst in the galaxy; the later the burst, the more intense the star formation. We discuss whether the higher SFEs in DSFGs could be due to mergers.
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