We present a quantitative analysis of the astrophysical and cosmological information that can be extracted from the many important wide-area, shallow surveys that will be carried out in the next few ...years. Our calculations combine the predictions of the physical model by Granato et al. for the formation and evolution of spheroidal galaxies with up-to-date phenomenological models for the evolution of starburst and normal late-type galaxies and of radio sources. We compute the expected number counts and the redshift distributions of these source populations separately and then focus on protospheroidal galaxies. For the latter objects, we predict the counts and redshift distributions of strongly lensed sources at 250, 350, 500 and 850 μm, the angular correlation function of sources detected in the surveys considered, and the angular power spectra due to clustering of sources below the detection limit in Herschel and Planck surveys. An optimal survey for selecting strongly lensed protospheroidal galaxies is described, and it is shown how they can be easily distinguished from the other source populations. We also discuss the detectability of the imprints of the one-halo and two-halo regimes on angular correlation functions and clustering power spectra, as well as the constraints on cosmological parameters that can be obtained from the determinations of these quantities. The novel data relevant to derive the first submillimetre estimates of the local luminosity functions of starburst and late-type galaxies, and the constraints on the properties of rare source populations, such as blazars, are also briefly described.
ABSTRACT We exploit the continuity equation approach and "main-sequence" star formation timescales to show that the observed high abundance of galaxies with stellar masses a few 1010 M at redshift z ...4 implies the existence of a galaxy population featuring large star formation rates (SFRs) 102 M yr−1 in heavily dust-obscured conditions. These galaxies constitute the high-redshift counterparts of the dusty star-forming population already surveyed for z 3 in the far-IR band by the Herschel Space Observatory. We work out specific predictions for the evolution of the corresponding stellar mass and SFR functions out to z ∼ 10, determining that the number density at z 8 for SFRs 30 M yr−1 cannot be estimated relying on the UV luminosity function alone, even when standard corrections for dust extinction based on the UV slope are applied. We compute the number counts and redshift distributions (including galaxy-scale gravitational lensing) of this galaxy population, and show that current data from the AzTEC-LABOCA, SCUBA-2, and ALMA-SPT surveys are already addressing it. We demonstrate how an observational strategy based on color preselection in the far-IR or (sub-)millimeter band with Herschel and SCUBA-2, supplemented by photometric data from on-source observations with ALMA, can allow us to reconstruct the bright end of the SFR functions out to z 8. In parallel, such a challenging task can be managed by exploiting current UV surveys in combination with (sub-)millimeter observations by ALMA and NIKA2 and/or radio observations by SKA and its precursors.
We investigate the astrophysics of radio-emitting star-forming galaxies and active galactic nuclei (AGNs) and elucidate their statistical properties in the radio band, including luminosity functions, ...redshift distributions, and number counts at sub-mJy flux levels, which will be crucially probed by next-generation radio continuum surveys. Specifically, we exploit the model-independent approach by Mancuso et al. to compute the star formation rate functions, the AGN duty cycles, and the conditional probability of a star-forming galaxy to host an AGN with given bolometric luminosity. Coupling these ingredients with the radio emission properties associated with star formation and nuclear activity, we compute relevant statistics at different radio frequencies and disentangle the relative contribution of star-forming galaxies and AGNs in different radio luminosity, radio flux, and redshift ranges. Finally, we highlight that radio-emitting star-forming galaxies and AGNs are expected to host supermassive black holes accreting with different Eddington ratio distributions and to occupy different loci in the galaxy main-sequence diagrams. These specific predictions are consistent with current data sets but need to be tested with larger statistics via future radio data with multiband coverage on wide areas, as will become routinely achievable with the advent of the Square Kilometre Array and its precursors.
ABSTRACT We provide a novel, unifying physical interpretation on the origin, average shape, scatter, and cosmic evolution for the main sequences of star-forming galaxies and active galactic nuclei ...(AGNs) at high redshift . We achieve this goal in a model-independent way by exploiting: (i) the redshift-dependent star formation rate functions based on the latest UV/far-IR data from HST/Herschel, and related statistics of strong gravitationally lensed sources; (ii) deterministic evolutionary tracks for the history of star formation and black hole accretion, gauged on a wealth of multiwavelength observations including the observed Eddington ratio distribution. We further validate these ingredients by showing their consistency with the observed galaxy stellar mass functions and AGN bolometric luminosity functions at different redshifts via the continuity equation approach. Our analysis of the main sequence for high-redshift galaxies and AGNs highlights that the present data are consistently interpreted in terms of an in situ coevolution scenario for star formation and black hole accretion, envisaging these as local, time-coordinated processes.
ABSTRACT
We report a remarkable overdensity of high-redshift submillimetre galaxies (SMG), 4–7 times the background, around a statistically complete sample of twelve 250 μm selected galaxies at z = ...0.35, which were targeted by ALMA in a study of gas tracers. This overdensity is consistent with the effect of lensing by the haloes hosting the target z = 0.35 galaxies. The angular cross-correlation in this sample is consistent with statistical measures of this effect made using larger sub-mm samples. The magnitude of the overdensity as a function of radial separation is consistent with intermediate scale lensing by haloes of the order of $7\times 10^{13}\mbox{ $\rm M_{\odot }$ }$, which should host one or possibly two bright galaxies and several smaller satellites. This is supported by observational evidence of interaction with satellites in four out of the six fields with SMG, and membership of a spectroscopically defined group for a fifth. We also investigate the impact of these SMG on the reported Herschel fluxes of the z = 0.35 galaxies, as they produce significant contamination in the 350 and 500 μm Herschel bands. The higher than random incidence of these boosting events implies a significantly larger bias in the sub-mm colours of Herschel sources associated with z < 0.7 galaxies than has previously been assumed, with fboost = 1.13, 1.26, 1.44 at 250, 350, and 500 μm . This could have implications for studies of spectral energy distributions, source counts, and luminosity functions based on Herschel samples at z = 0.2–0.7.
The Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) is a survey of 550 deg2 with the Herschel Space Observatory in five far-infrared and submillimetre bands. The first data for ...the survey, observations of a field 4 × 4 deg2 in size, were taken during the Science Demonstration Phase (SDP), and reach a 5σ noise level of 33.5 mJy beam−1 at 250 μm. This paper describes the source extraction methods used to create the corresponding SDP catalogue, which contains 6876 sources, selected at 250 μm, within ∼14 deg2. Spectral and Photometric Imaging REciever (SPIRE) sources are extracted using a new method specifically developed for Herschel data and Photodetector Array Camera and Spectrometer (PACS) counterparts of these sources are identified using circular apertures placed at the SPIRE positions. Aperture flux densities are measured for sources identified as extended after matching to optical wavelengths. The reliability of this catalogue is also discussed, using full simulated maps at the three SPIRE bands. These show that a significant number of sources at 350 and 500 μm have undergone flux density enhancements of up to a factor of ∼2, due mainly to source confusion. Correction factors are determined for these effects. The SDP data set and corresponding catalogue will be available from http://www.h-atlas.org.
Context. This work focuses on the submillimeter galaxy magnification bias, specifically in the tomographic scenario. It builds upon previous works, while utilising updated data to refine the ...methodology employed in constraining the free parameters of the halo occupation distribution model and cosmological parameters within a flat ΛCDM model. Aims. This work aims to optimise CPU time and explore strategies for analysing different redshift bins, while maintaining measurement precision. Additionally, it seeks to examine the impact of excluding the GAMA15 field, one of the H-ATLAS fields that was found to have an anomalous strong cross-correlation signal, and increasing the number of redshift bins on the results. Methods. The study uses a tomographic approach, dividing the redshift range into a different number of bins and analysing cross-correlation measurements between H-ATLAS submillimeter galaxies with photometric redshifts in the range 1.2 < z < 4.0 and foreground GAMA galaxies with spectroscopic redshifts in the range 0.01 < z < 0.9. Interpreting the weak lensing signal within the halo model formalism and carrying out a Markov chain Monte Carlo algorithm, we obtain the posterior distribution of both halo occupation distribution and cosmological parameters within a flat ΛCDM model. Comparative analyses are conducted between different scenarios, including different combinations of redshift bins and the inclusion or exclusion of the GAMA15 field. Results. The mean-redshift approximation employed in the “base case” yields results that are in good agreement with the more computationally intensive “full model” case. Marginalised posterior distributions confirm a systematic increase in the minimum mass of the lenses with increasing redshift. The inferred cosmological parameters show narrower posterior distributions compared to previous studies on the same topic, indicating reduced measurement uncertainties. Excluding the GAMA15 field demonstrates a reduction in the cross-correlation signal, particularly in two of the redshift bins, suggesting a sample variance within the large-scale structure along the line of sight. Moreover, extending the redshift range improves the robustness against the sample variance issue and produces similar, but tighter constraints compared to excluding the GAMA15 field. Conclusions. The study emphasises the importance of considering sample variance and redshift binning in tomographic analyses. Increasing the number of independent fields and the number of redshift bins can minimise both the spatial and redshift sample variance, resulting in more robust measurements. The adoption of additional wide area field observed by Herschel and of updated foreground catalogues, such as the Dark Energy Survey or the future Euclid mission, is important for implementing these approaches effectively.
Aims.
The main purpose of this work is to provide a proof-of-concept method to derive tabulated observational constraints on the halo mass function (HMF) by studying the magnification bias effect on ...high-redshift submillimeter galaxies. Under the assumption of universality, we parametrize the HMF according to two traditional models, namely the Sheth and Tormen (ST) and Tinker fits, derive posterior distributions for their parameters, and assess their performance in explaining the measured data within the Λ cold dark matter model. We also study the potential influence of the halo occupation distribution (HOD) parameters in this analysis and discuss two aspects regarding the HMF parametrization, namely its normalization and the possibility of allowing negative values for the parameters.
Methods.
We measure the cross-correlation function between a foreground sample of GAMA galaxies with spectroscopic redshifts in the range 0.2 <
z
< 0.8 and a background sample of H-ATLAS galaxies with photometric redshifts in the range 1.2 <
z
< 4.0 and carry out a Markov chain Monte Carlo algorithm in the context of Bayesian inference to check this observable against its mathematical prediction within the halo model formalism, which depends on both the HOD and HMF parameters.
Results.
Under the assumption that all HMF parameters are positive, the ST fit only seems to fully explain the measurements by forcing the mean number of satellite galaxies in a halo to increase substantially from its prior mean value. The Tinker fit, on the other hand, provides a robust description of the data without relevant changes in the HOD parameters, but with some dependence on the prior range of two of its parameters. When the normalization condition for the HMF is dropped and we allow negative values of the
p
1
parameter in the ST fit, all the involved parameters are better determined, unlike the previous models, thus deriving the most general HMF constraints. While all the aforementioned cases are in agreement with the traditional fits within the uncertainties, the last one hints at a slightly higher number of halos at intermediate and high masses, raising the important point of the allowed parameter range.
We combine the latest data sets obtained with different surveys to study the frequency dependence of polarized emission coming from extragalactic radio sources (ERS). We consider data over a very ...wide frequency range starting from 1.4 GHz up to 217 GHz. This range is particularly interesting since it overlaps the frequencies of the current and forthcoming cosmic microwave background (CMB) experiments. Current data suggest that at high radio frequencies ( ≥ 20 GHz) the fractional polarization of ERS does not depend on the total flux density. Conversely, recent data sets indicate a moderate increase of polarization fraction as a function of frequency, physically motivated by the fact that Faraday depolarization is expected to be less relevant at high radio frequencies. We compute ERS number counts using updated models based on recent data, and we forecast the contribution of unresolved ERS in CMB polarization spectra. Given the expected sensitivities and the observational patch sizes of forthcoming CMB experiments, about ∼200 (up to ∼2000) polarized ERS are expected to be detected. Finally, we assess that polarized ERS can contaminate the cosmological B-mode polarization if the tensor-to-scalar ratio is <0.05 and they have to be robustly controlled to de-lens CMB B-modes at the arcminute angular scales.
ABSTRACT
We present SCUBA-2 850 $\mathrm{ \mu}$m observations of 13 candidate starbursting protoclusters selected using Planck and Herschel data. The cumulative number counts of the 850 $\mathrm{ ...\mu}$m sources in 9 of 13 of these candidate protoclusters show significant overdensities compared to the field, with the probability <10−2 assuming the sources are randomly distributed in the sky. Using the 250, 350, 500, and 850 $\mathrm{ \mu}$m flux densities, we estimate the photometric redshifts of individual SCUBA-2 sources by fitting spectral energy distribution templates with an MCMC method. The photometric redshift distribution, peaking at 2 < z < 3, is consistent with that of known z > 2 protoclusters and the peak of the cosmic star formation rate density (SFRD). We find that the 850 $\mathrm{ \mu}$m sources in our candidate protoclusters have infrared luminosities of $L_{\mathrm{IR}}\gtrsim 10^{12}\, \mathrm{L}_{\odot }$ and star formation rates of SFR = (500–1500) M⊙ yr−1. By comparing with results in the literature considering only Herschel photometry, we conclude that our 13 candidate protoclusters can be categorized into four groups: six of them being high-redshift starbursting protoclusters, one being a lower redshift cluster or protocluster, three being protoclusters that contain lensed dusty star-forming galaxies or are rich in 850 $\mathrm{ \mu}$m sources, and three regions without significant Herschel or SCUBA-2 source overdensities. The total SFRs of the candidate protoclusters are found to be comparable or higher than those of known protoclusters, suggesting our sample contains some of the most extreme protocluster population. We infer that cross-matching Planck and Herschel data is a robust method for selecting candidate protoclusters with overdensities of 850 $\mathrm{ \mu}$m sources.
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