arXiv subjects

Joaquin Gonzalez-Nuevo

Publications and source records attributed to Joaquin Gonzalez-Nuevo.

15 recordsLinked to original sources

arXiv2025

AtLAST -- Cosmology with submillimetre galaxies magnification bias

Magnification bias offers a uniquely powerful and independent route to cosmological information. As a gravitational-lensing observable, it probes galaxy-matter correlations without relying on galaxy shapes, PSF modelling, or intrinsic-alignment corrections. Its sensitivity spans both geometry and growth: magnification bias simultaneously responds to the matter density, the amplitude of structure, and the redshift evolution of dark energy (DE) below $z \leq 1$. Importantly, its parameter degeneracy directions differ from those of shear, Baryon Acoustic Oscillations (BAO), and Cosmic Microwave Background (CMB) data, making it a complementary and consistency-check probe with substantial diagnostic value for the next decade of precision cosmology. However, the current potential of magnification bias is restricted by limited sky coverage, catalogue inhomogeneities, and insufficiently precise redshift or number-count characterisation. A next-generation wide-field submillimetre facility like AtLAST -- capable of uniform, deep surveys and spectroscopic mapping -- would overcome these limitations and transform magnification bias into a competitive, high-precision cosmological tool.

astro-ph.CO↗

arXiv2023

Characterisation of Herschel-selected strong lens candidates through HST and sub-mm/mm observations

We have carried out HST snapshot observations at 1.1 $μ$m of 281 candidate strongly lensed galaxies identified in the wide-area extragalactic surveys conducted with the Herschel space observatory. Our candidates comprise systems with flux densities at $500\,μ$m$ S_{500}\geq 80$ mJy. We model and subtract the surface brightness distribution for 130 systems, where we identify a candidate for the foreground lens candidate. After combining visual inspection, archival high-resolution observations, and lens subtraction, we divide the systems into different classes according to their lensing likelihood. We confirm 65 systems to be lensed. Of these, 30 are new discoveries. We successfully perform lens modelling and source reconstruction on 23 systems, where the foreground lenses are isolated galaxies and the background sources are detected in the HST images. All the systems are successfully modelled as a singular isothermal ellipsoid. The Einstein radii of the lenses and the magnifications of the background sources are consistent with previous studies. However, the background source circularised radii (between 0.34 kpc and 1.30 kpc) are $\sim$3 times smaller than the ones measured in the sub-mm/mm for a similarly selected and partially overlapping sample. We compare our lenses with those in the SLACS survey, confirming that our lens-independent selection is more effective at picking up fainter and diffuse galaxies and group lenses. This sample represents the first step towards characterising the near-IR properties and stellar masses of the gravitationally lensed dusty star-forming galaxies.

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arXiv2020

Over-density of SMGs in fields containing z~0.3 galaxies: magnification bias and the implications for studies of galaxy evolution

We report a remarkable over-density of high-redshift submillimetre galaxies (SMG), 4-7 times the background, around a statistically complete sample of twelve 250-micron selected galaxies at z=0.35, which were targeted by ALMA in a study of gas tracers. This over-density is consistent with the effect of lensing by the halos 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 over-density as a function of radial separation is consistent with intermediate scale lensing by halos of order 7x 10^{13} M_o, 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-micron 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 f_boost = 1.13, 1.26, 1.44 at 250, 350 and 500-microns. 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.

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arXiv2019

Radio sources in next-generation CMB surveys

CMB surveys provide, for free, blindly selected samples of extragalactic radio sources at much higher frequencies than traditional radio surveys. Next-generation, ground-based CMB experiments with arcmin resolution at mm wavelengths will provide samples of thousands radio sources allowing the investigation of the evolutionary properties of blazar populations, the study of the earliest and latest stages of radio activity, the discovery of rare phenomena and of new transient sources and events. Space-borne experiments will extend to sub-mm wavelengths the determinations of the SEDs of many hundreds of blazars, in temperature and in polarization, allowing us to investigate the flow and the structure of relativistic jets close to their base, and the electron acceleration mechanisms. A real breakthrough will be achieved in the caracterization of the polarization properties. The first direct counts in polarization will be obtained, enabling a solid assessment of the extra-galactic source contamination of CMB maps and allowing us to understand structure and intensity of magnetic fields, particle densities and structures of emitting regions close to the base of the jet.

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arXiv2019

Early evolution of galaxies and of large-scale structure from CMB experiments

Next generation CMB experiments with arcmin resolution will, for free, lay the foundations for a real breakthrough on the study of the early evolution of galaxies and galaxy clusters, thanks to the detection of large samples of strongly gravitationally lensed galaxies and of proto-clusters of dusty galaxies up to high redshifts. This has an enormous legacy value. High resolution follow-up of strongly lensed galaxies will allow the direct investigation of their structure and kinematics up to z~6, providing direct information on physical processes driving their evolution. Follow-up of proto-clusters will allow an observational validation of the formation history of the most massive dark matter halos up to z~4, well beyond the redshift range accessible via X-ray or SZ measurements. These experiments will also allow a giant leap forward in the determination of polarization properties of extragalactic sources, and will provide a complete census of cold dust available for star formation in the local universe.

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arXiv2018

Broadband spectral energy distributions of SDSS-selected quasars and of their host galaxies: intense activity at the onset of AGN feedback

We present the mean spectral energy distribution (SED) of a sample of optically selected quasars (QSOs) at redshifts of $1 \le z \le 5$. To derive it, we exploit photometric information from SDSS, UKIDSS, and WISE surveys in combination with a stacking analysis of \textit{Herschel}, \textit{AKARI}, and \textit{Planck} maps at the location of the QSOs. The near-UV and optical parts of the reconstructed mean rest-frame SED are similar to those found in other studies. However, the SED shows an excess at 1-2 $μ$m (when compared to the aforementioned SEDs normalized in the near-UV) and a prominent bump around 4-6 $μ$m, followed by a decrease out to $\sim 20 \,μ$m and a subsequent far-IR bump. From the fitted SEDs we estimate the average active galactic nuclei (AGN) luminosity $L_{\rm AGN}$ and star formation rate (SFR) as function of cosmic time, finding typical $L_{\rm AGN} \sim 10^{46} - 10^{47}$ erg/s and SFR $\sim 50 - 1000\, M_{\odot}/$yr. We develop mid-IR based criteria to split the QSO sample, finding that these allow us to move along the average relationship in the SFR vs. $L_{\rm AGN}$ diagram toward increasing AGN luminosities. When interpreted in the context of the in-situ coevolution scenario presented by Lapi et al. 2014, our results suggest that the detection in the far-IR band is an effective criterion to select objects where the star formation is on the verge of being affected by energy/momentum feedback from the central AGN.

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arXiv2016

Multi-wavelength lens reconstruction of a $\textit{Planck}$ $\&$ $\textit{Herschel}$-detected star-bursting galaxy

We present a source-plane reconstruction of a ${\it Herschel}$ and ${\it Planck}$-detected gravitationally-lensed dusty star-forming galaxy (DSFG) at $z=1.68$ using {\it Hubble}, Sub-millimeter Array (SMA), and Keck observations. The background sub-millimeter galaxy (SMG) is strongly lensed by a foreground galaxy cluster at $z=0.997$ and appears as an arc of length $\sim 15^{\prime \prime}$ in the optical images. The continuum dust emission, as seen by SMA, is limited to a single knot within this arc. We present a lens model with source plane reconstructions at several wavelengths to show the difference in magnification between the stars and dust, and highlight the importance of a multi-wavelength lens models for studies involving lensed DSFGs. We estimate the physical properties of the galaxy by fitting the flux densities to model SEDs leading to a magnification-corrected star formation rate of $390 \pm 60$ M$_{\odot}$ yr$^{-1}$ and a stellar mass of $1.1 \pm 0.4\times 10^{11}$ M$_{\odot}$. These values are consistent with high-redshift massive galaxies that have formed most of their stars already. The estimated gas-to-baryon fraction, molecular gas surface density, and SFR surface density have values of $0.43 \pm 0.13$, $350 \pm 200$ M$_{\odot}$ pc$^{-2}$, and $\sim 12 \pm 7~$M$_{\odot}$ yr$^{-1}$ kpc$^{-2}$, respectively. The ratio of star formation rate surface density to molecular gas surface density puts this among the most star-forming systems, similar to other measured SMGs and local ULIRGS.

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arXiv2016

Toward a tomographic analysis of the cross-correlation between Planck CMB lensing and H-ATLAS galaxies

We present an improved and extended analysis of the cross-correlation between the map of the Cosmic Microwave Background (CMB) lensing potential derived from the \emph{Planck} mission data and the high-redshift galaxies detected by the \emph{Herschel} Astrophysical Terahertz Large Area Survey (H-ATLAS) in the photometric redshift range $z_{\rm ph} \ge 1.5$. We compare the results based on the 2013 and 2015 \textit{Planck} datasets, and investigate the impact of different selections of the H-ATLAS galaxy samples. Significant improvements over our previous analysis have been achieved thanks to the higher signal-to-noise ratio of the new CMB lensing map recently released by the \textit{Planck} collaboration. The effective galaxy bias parameter, $b$, for the full galaxy sample, derived from a joint analysis of the cross-power spectrum and of the galaxy auto-power spectrum is found to be $b = 3.54^{+0.15}_{-0.14}$. Furthermore, a first tomographic analysis of the cross-correlation signal is implemented, by splitting the galaxy sample into two redshift intervals: $1.5 \le z_{\rm ph} < 2.1$ and $z_{\rm ph}\ge 2.1$. A statistically significant signal was found for both bins, indicating a substantial increase with redshift of the bias parameter: $b=2.89\pm0.23$ for the lower and $b=4.75^{+0.24}_{-0.25}$ for the higher redshift bin. Consistently with our previous analysis we find that the amplitude of the cross correlation signal is a factor of $1.45^{+0.14}_{-0.13}$ higher than expected from the standard $Λ$CDM model for the assumed redshift distribution. The robustness of our results against possible systematic effects has been extensively discussed although the tension is mitigated by passing from 4 to 3$σ$.

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arXiv2015

Far-infrared observations of an unbiased sample of gamma-ray burst host galaxies

Gamma-ray bursts (GRBs) are the most energetic phenomena in the Universe; believed to result from the collapse and subsequent explosion of massive stars. Even though it has profound consequences for our understanding of their nature and selection biases, little is known about the dust properties of the galaxies hosting GRBs. We present analysis of the far-infrared properties of an unbiased sample of 20 \textit{BeppoSAX} and \textit{Swift} GRB host galaxies (at an average redshift of $z\,=\,3.1$) located in the {\it Herschel} Astrophysical Terahertz Large Area Survey, the {\it Herschel} Virgo Cluster Survey, the {\it Herschel} Fornax Cluster Survey, the {\it Herschel} Stripe 82 Survey and the {\it Herschel} Multi-tiered Extragalactic Survey, totalling $880$ deg$^2$, or $\sim 3$\% of the sky in total. Our sample selection is serendipitous, based only on whether the X-ray position of a GRB lies within a large-scale {\it Herschel} survey -- therefore our sample can be considered completely unbiased. Using deep data at wavelengths of 100\,--\,500$\,μ$m, we tentatively detected 1 out of 20 GRB hosts located in these fields. We constrain their dust masses and star formation rates (SFRs), and discuss these in the context of recent measurements of submillimetre galaxies and ultraluminous infrared galaxies. The average far-infrared flux of our sample gives an upper limit on SFR of $<114\,{\rm M}\odot\,\mbox{yr}^{-1}$. The detection rate of GRB hosts is consistent with that predicted assuming that GRBs trace the cosmic SFR density in an unbiased way, i.e. that the fraction of GRB hosts with $\mbox{SFR}>500\,{\rm M}\odot\,\mbox{yr}^{-1}$ is consistent with the contribution of such luminous galaxies to the cosmic star formation density.

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arXiv2014

PRISM (Polarized Radiation Imaging and Spectroscopy Mission): An Extended White Paper

PRISM (Polarized Radiation Imaging and Spectroscopy Mission) was proposed to ESA in May 2013 as a large-class mission for investigating within the framework of the ESA Cosmic Vision program a set of important scientific questions that require high resolution, high sensitivity, full-sky observations of the sky emission at wavelengths ranging from millimeter-wave to the far-infrared. PRISM's main objective is to explore the distant universe, probing cosmic history from very early times until now as well as the structures, distribution of matter, and velocity flows throughout our Hubble volume. PRISM will survey the full sky in a large number of frequency bands in both intensity and polarization and will measure the absolute spectrum of sky emission more than three orders of magnitude better than COBE FIRAS. The aim of this Extended White Paper is to provide a more detailed overview of the highlights of the new science that will be made possible by PRISM

astro-ph.CO↗

arXiv2013

PRISM (Polarized Radiation Imaging and Spectroscopy Mission): A White Paper on the Ultimate Polarimetric Spectro-Imaging of the Microwave and Far-Infrared Sky

PRISM (Polarized Radiation Imaging and Spectroscopy Mission) was proposed to ESA in response to the Call for White Papers for the definition of the L2 and L3 Missions in the ESA Science Programme. PRISM would have two instruments: (1) an imager with a 3.5m mirror (cooled to 4K for high performance in the far-infrared---that is, in the Wien part of the CMB blackbody spectrum), and (2) an Fourier Transform Spectrometer (FTS) somewhat like the COBE FIRAS instrument but over three orders of magnitude more sensitive. Highlights of the new science (beyond the obvious target of B-modes from gravity waves generated during inflation) made possible by these two instruments working in tandem include: (1) the ultimate galaxy cluster survey gathering 10e6 clusters extending to large redshift and measuring their peculiar velocities and temperatures (through the kSZ effect and relativistic corrections to the classic y-distortion spectrum, respectively) (2) a detailed investigation into the nature of the cosmic infrared background (CIB) consisting of at present unresolved dusty high-z galaxies, where most of the star formation in the universe took place, (3) searching for distortions from the perfect CMB blackbody spectrum, which will probe a large number of otherwise inaccessible effects (e.g., energy release through decaying dark matter, the primordial power spectrum on very small scales where measurements today are impossible due to erasure from Silk damping and contamination from non-linear cascading of power from larger length scales). These are but a few of the highlights of the new science that will be made possible with PRISM.

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arXiv2012

The local luminosity function of star-forming galaxies derived from the Planck Early Release Compact Source Catalogue

The Planck Early Release Compact Source Catalog (ERCSC) has offered the first opportunity to accurately determine the luminosity function of dusty galaxies in the very local Universe (i.e. distances <~ 100 Mpc), at several (sub-)millimetre wavelengths, using blindly selected samples of low redshift sources, unaffected by cosmological evolution. This project, however, requires careful consideration of a variety of issues including the choice of the appropriate flux density measurement, the separation of dusty galaxies from radio sources and from Galactic sources, the correction for the CO emission, the effect of density inhomogeneities, and more. We present estimates of the local luminosity functions at 857 GHz (350 microns), 545 GHz (550 microns) and 353 GHz (850 microns) extending across the characteristic luminosity L_star, and a preliminary estimate over a limited luminosity range at 217 GHz (1382 microns). At 850 microns and for luminosities L >~ L_star our results agree with previous estimates, derived from the SCUBA Local Universe Galaxy Survey (SLUGS), but are higher than the latter at L <~ L_star. We also find good agreement with estimates at 350 and 500 microns based on preliminary Herschel survey data.

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arXiv2011

The Planck-ATCA Coeval Observations (PACO) project: the faint sample

The Planck-ATCA Co-eval Observations (PACO) project collected data between 4.5 and 40 GHz for 482 sources selected within the Australia Telescope 20 GHz (AT20G) catalogue and observed with the Australia Telescope Compact Array (ATCA). Observations were done almost simultaneously with the Planck satellite, in the period between July 2009 and August 2010. In this paper we present and discuss the data for the complete sample of 159 sources with S(AT20G)>200 mJy in the Southern ecliptic pole region. The Planck Early Release Compact Source Catalogue (ERCSC) contains 57 of our sources. A comparison between the PACO catalogue and the ERCSC confirms that the reliability of the latter is better than 95 per cent. The missing ERCSC sources are typically associated with the Large Magellanic Cloud, the Milky Way or are otherwise extended. The spectral analysis of the PACO faint catalogue shows a spectral steepening of the sources at high frequencies, confirming the results obtained from the PACO bright sample. A comparison with AT20G measurements, carried out, on average, a few years earlier, has demonstrated that, on these timescales, our sources show a rather high variability with an rms amplitude of ~40 per cent at 20 GHz. The source spectral properties are found not to vary substantially with flux density, except for an increase of the fraction of steep spectrum sources at fainter flux densities. Our data also allow us to extend by a factor ~5 downwards in flux density the source counts at ~33 GHz and ~40 GHz obtained from Planck's Early Release Compact Source catalogue. This allows us to substantially improve our control on the contribution of unresolved extragalactic sources to the power spectrum of small scale fluctuations in CMB maps.

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arXiv2006

Polarized synchrotron emission

Galactic synchrotron emission represents the most relevant foreground contamination in cosmic microwave background (CMB) anisotropy observations at angular scales $θ\gsim 1^\circ$ and frequencies $ν\lsim 70$ GHz. The accurate understanding of its polarization properties is crucial to extract the cosmological information contained in the CMB polarization anisotropy. Radio surveys at $ν\sim 1$ GHz offer the unique opportunity to study Galactic synchrotron emission where it represents the dominant component, possibly except for regions close to the Galactic plane where free-free emission is also important. We review the observational status of Galactic radio surveys at scales $θ\gsim 0.5^\circ$. Leiden surveys, thanks to their frequency coverage from 0.408 GHz to 1.411 GHz, still remain of fundamental importance for the comprehension of depolarization phenomena. Recent surveys at 1.42 GHz (in both total intensity and polarization) with a better sensitivity and sky sampling now cover both celestial hemispheres and allow to accurately map the correlation properties of the diffuse synchrotron emission. We present an analysis of these surveys in terms of angular power spectrum. A comparison of a simple frequency extrapolation of these results with the recent WMAP results shows that we are close to map the bulk of the diffuse synchrotron polarization fluctuations and to understand the corresponding implications for CMB experiments.

astro-ph↗

arXiv2004

Predictions for high-frequency radio surveys of extragalactic sources

We present detailed predictions of the contributions of the various source populations to the counts at frequencies of tens of GHz. New evolutionary models are worked out for flat-spectrum radio quasars, BL Lac objects, and steep-spectrum sources. Source populations characterized by spectra peaking at high radio frequencies, such as extreme GPS sources, ADAF/ADIOS sources and early phases of gamma-ray burst afterglows are also dealt with. The counts of different populations of star-forming galaxies (normal spirals, starbursts, high-z galaxies detected by SCUBA and MAMBO surveys, interpreted as proto-spheroidal galaxies) are estimated taking into account both synchrotron and free-free emission, and dust re-radiation. Our analysis is completed by updated counts of Sunyaev-Zeldovich effects in clusters of galaxies and by a preliminary estimate of galactic-scale Sunyaev-Zeldovich signals associated to proto-galactic plasma.

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