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.
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.
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.
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.
Abstract
We estimate the average fractional polarization at 143, 217 and 353 GHz of a sample of 4697 extragalactic dusty sources by applying stacking technique. The sample is selected from the second ...version of the Planck Catalogue of Compact Sources at 857 GHz, avoiding the region inside the Planck Galactic mask (f
sky ∼ 60 per cent). We recover values for the mean fractional polarization at 217 and 353 GHz of (3.10 ± 0.75) per cent and (3.65 ± 0.66) per cent, respectively, whereas at 143 GHz we give a tentative value of (3.52 ± 2.48) per cent. We discuss the possible origin of the measured polarization, comparing our new estimates with those previously obtained from a sample of radio sources. We test different distribution functions and we conclude that the fractional polarization of dusty sources is well described by a log-normal distribution, as determined in the radio band studies. For this distribution we estimate μ217GHz = 0.3 ± 0.5 that would correspond to a median fractional polarization of Πmed = (1.3 ± 0.7) per cent and μ353GHz = 0.7 ± 0.4 (Πmed = (2.0 ± 0.8) per cent), σ217GHz = 1.3 ± 0.2 and σ353GHz = 1.1 ± 0.2. With these values we estimate the source number counts in polarization and the contribution given by these sources to the Cosmic Microwave Background B-mode angular power spectrum at 217, 353, 600 and 800 GHz. We conclude that extragalactic dusty sources might be an important contaminant for the primordial B-mode at frequencies >217 GHz.
ABSTRACT
Using the Eight MIxer Receiver (EMIR) instrument on the Institut de RadioAstronomie Millimétrique (IRAM) 30-m telescope, we conducted a spectroscopic redshift search of seven zphot ∼ 4 ...submillimetre bright galaxies selected from the Herschel Bright Sources sample with fluxes at 500 μm greater than 80 mJy. For four sources, we obtained spectroscopic redshifts between 3.4 < z < 4.1 through the detection of multiple CO-spectral lines with J ≥ 3. Later, we detected low-J transitions for two of these sources with the Green Bank Telescope including the CO(1–0) transition. For the remaining three sources, more data are needed to determine the spectroscopic redshift unambiguously. The measured CO luminosities and line widths suggest that all these sources are gravitationally lensed. These observations demonstrate that the 2 mm window is indispensable to confirm robust spectroscopic redshifts for z < 4 sources. Finally, we present an efficient graphical method to correctly identify spectroscopic redshifts.
Context. Gravitational lensing is a powerful tool for studying the distribution of mass in the Universe. Understanding the magnification bias effect in gravitational lensing and its impact on the ...flux of sub-millimetre galaxies (SMGs) is crucial for accurate interpretations of observational data. Aims. This study aims to investigate the magnification bias effect in the context of gravitational lensing and analyse the mass density profiles of different types of foreground lenses, including quasi-stellar objects (QSOs), galaxies, and galaxy clusters. The specific goals are to compare the lens types, assess the impact of angular resolution on the analysis, and determine the adequacy of theoretical mass density profiles in explaining the observed data. Methods. The magnification bias was estimated using the cross-correlation function between the positions of background SMGs and foreground lens samples. Stacking techniques were employed to enhance the signal at smaller angular separations, and the more precise positions from the WISE catalogue were utilised to improve positional accuracy. Four different theoretical mass density profiles were analysed to extract additional information. Results. The cross-correlation measurements revealed distinctive central excess and outer power-law profiles, with a lack of signal in the intermediate region. The lens types exhibited varying signal strengths, with QSOs producing the strongest signal and galaxy clusters showing weaker signals. The analysis of mass density profiles indicated limitations in the selected profiles’ ability to explain the observed data, highlighting the need for additional considerations. The lack of extended emission in the QSO sample suggested possible influences from close satellites along the line of sight in the other lens types. Conclusions. The study provides valuable insights into the magnification bias effect and mass density profiles in gravitational lensing. The results suggest the presence of isolated galactic halos and the importance of considering environmental factors and close satellites in future investigations. The derived masses and best-fit parameters contribute to our understanding of lensing systems and provide constraints on the nature of central galaxies. Notably, the intriguing lack of signal around 10 arcsec challenges current understanding and calls for further quantitative analysis and confirmation of the observed feature.
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.
Context.
The study of the magnification bias produced on high-redshift sub-millimetre galaxies by foreground galaxies through the analysis of the cross-correlation function was recently demonstrated ...as an interesting independent alternative to the weak-lensing shear as a cosmological probe.
Aims.
In the case of the proposed observable, most of the cosmological constraints mainly depend on the largest angular separation measurements. Therefore, we aim to study and correct the main large-scale biases that affect foreground and background galaxy samples to produce a robust estimation of the cross-correlation function. Then we analyse the corrected signal to derive updated cosmological constraints.
Methods.
We measured the large-scale, bias-corrected cross-correlation functions using a background sample of H-ATLAS galaxies with photometric redshifts > 1.2 and two different foreground samples (GAMA galaxies with spectroscopic redshifts or SDSS galaxies with photometric ones, both in the range 0.2 <
z
< 0.8). These measurements are modelled using the traditional halo model description that depends on both halo occupation distribution and cosmological parameters. We then estimated these parameters by performing a Markov chain Monte Carlo under multiple scenarios to study the performance of this observable and how to improve its results.
Results.
After the large-scale bias corrections, we obtain only minor improvements with respect to the previous magnification bias results, mainly confirming their conclusions: a lower bound on Ω
m
> 0.22 at 95% CL and an upper bound
σ
8
< 0.97 at 95% CL (results from the
z
spec
sample). Neither the much higher surface density of the foreground photometric sample nor the assumption of Gaussian priors for the remaining unconstrained parameters significantly improve the derived constraints. However, by combining both foreground samples into a simplified tomographic analysis, we were able to obtain interesting constraints on the Ω
m
−
σ
8
plane as follows: Ω
m
= 0.50
−0.20
+0.14
and σ
8
= 0.75
−0.10
+0.07
at 68% CL.
We use the Herschel-ATLAS survey to conduct the first large-scale statistical study of the submillimetre properties of optically selected galaxies. Using ∼80 000 r-band selected galaxies from 126 ...deg2 of the GAMA survey, we stack into submillimetre imaging at 250, 350 and 500 μ m to gain unprecedented statistics on the dust emission from galaxies at z < 0.35. We find that low-redshift galaxies account for 5 per cent of the cosmic 250-μm background (4 per cent at 350 μ m; 3 per cent at 500 μ m), of which approximately 60 per cent comes from 'blue' and 20 per cent from 'red' galaxies (rest-frame g−r). We compare the dust properties of different galaxy populations by dividing the sample into bins of optical luminosity, stellar mass, colour and redshift. In blue galaxies we find that dust temperature and luminosity correlate strongly with stellar mass at a fixed redshift, but red galaxies do not follow these correlations and overall have lower luminosities and temperatures. We make reasonable assumptions to account for the contaminating flux from lensing by red-sequence galaxies and conclude that galaxies with different optical colours have fundamentally different dust emission properties. Results indicate that while blue galaxies are more luminous than red galaxies due to higher temperatures, the dust masses of the two samples are relatively similar. Dust mass is shown to correlate with stellar mass, although the dust-to-stellar mass ratio is much higher for low stellar mass galaxies, consistent with the lowest mass galaxies having the highest specific star formation rates. We stack the 250 μ m-to-NUV luminosity ratio, finding results consistent with greater obscuration of star formation at lower stellar mass and higher redshift. Submillimetre luminosities and dust masses of all galaxies are shown to evolve strongly with redshift, indicating a fall in the amount of obscured star formation in ordinary galaxies over the last four billion years.
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