INAF–Osservatorio Astronomico di Padova
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The ESA Euclid mission will measure the photometric redshifts of billions of galaxies in order to provide an accurate 3D view of the Universe at optical and near-infrared wavelengths. Photometric redshifts are determined by the PHZ processing function on the basis of the multi-wavelength photometry of Euclid and ground-based observations. In this paper, we describe the PHZ processing used for the Euclid Quick Data Release, the output products, and their validation. The PHZ pipeline is responsible for the following main tasks: source classification into star, galaxy, and QSO classes based on photometric colours; determination of photometric redshifts and of physical properties of galaxies. The classification is able to provide a star sample with a high level of purity, a highly complete galaxy sample, and reliable probabilities of belonging to those classes. The identification of QSOs is more problematic: photometric information seems to be insufficient to accurately separate QSOs from galaxies. The performance of the pipeline in the determination of photometric redshifts has been tested using the COSMOS2020 catalogue and a large sample of spectroscopic redshifts. The results are in line with expectations: the precision of the estimates are compatible with Euclid requirements, while, as expected, a bias correction is needed to achieve the accuracy level required for the cosmological probes. Finally, the pipeline provides reliable estimates of the physical properties of galaxies, in good agreement with findings from the COSMOS2020 catalogue, except for an unrealistically large fraction of very young galaxies with very high specific star-formation rates. The application of appropriate priors is, however, sufficient to obtain reliable physical properties for those problematic objects. We present several areas for improvement for future Euclid data releases.
We present the Cosmic Evolution Early Release Science Survey (CEERS) catalog, including space-based photometry, photometric redshifts, and physical parameters for more than 80,000 galaxies. The imaging used for this catalog comes from the CEERS survey, which has NIRCam coverage over ~100 sq. arcmin of the Extended Groth Strip (EGS) in seven filters from 1.15μ\mum to 4.44μ\mum. Alongside these data, we also include ancillary HST imaging in seven filters from 0.435μ\mum to 1.6μ\mum. We used Source Extractor with hot and cold detection settings to extract photometry. We derive photometric redshifts using the spectral energy distribution (SED) modeling code, LePHARE, and estimate their accuracy using spectroscopically confirmed galaxies out to z10z\sim10, with σNMAD\sigma_{NMAD} ranging from 0.035-0.073, depending strongly on galaxy magnitude and redshift. We compute stellar masses, star formation rates, and E(B-V) using three different SED fitting codes with different templates and assumptions about the galaxy star formation histories. All of these measurements, as well as the full mosaics in all filters, and redshift probability distribution functions, are made available via the CEERS DR1.0 data release.
Low mass (sub)stellar objects represent the low end of the initial mass function, the transition to free-floating planets and a prominent interloper population in the search for high-redshift galaxies. Without proper motions or spectroscopy, can one identify these objects photometrically? JWST/NIRCam has several advantages over HST/WFC3 NIR: more filters, a greater wavelength range, and greater spatial resolution. Here, we present a catalogue of (sub)stellar dwarfs identified in the Cosmic Evolution Early Release Science Survey (CEERS). We identify 518 stellar objects down to mF200W28m_F200W \sim 28 using half-light radius, a full three magnitudes deeper than typical HST/WFC3 images. A kNN nearest neighbour algorithm identifies and types these sources, using four HST/WFC3 and four NIRCam filters, trained on SpeX spectra of nearby brown dwarfs. The kNN with four neighbors classifies well within two subtypes: e.g M2±\pm2 or T4±\pm2, achieving \sim95% precision and recall. More granular typing results in worse metrics. In CEERS, we find 9 M8±\pm2, 2 L6±\pm2, 1 T4±\pm2, and 15 T8±\pm2. We compare the observed long wavelength NIRCam colours -- not used in the kNN -- to those expected for brown dwarf atmospheric models. The NIRCam F356W-F444W and F410M-F444W colours are redder by a magnitude for the type assigned by the kNN, hinting at a wider variety of atmospheres for these objects. We find a 300-350pc scale-height for M6±\pm2 dwarfs plus a second structural component and a 150-200pc scale-height for T6±\pm2 type dwarfs, consistent with literature values.
We review the main physical processes that lead to the formation of stellar binary black holes (BBHs) and to their merger. BBHs can form from the isolated evolution of massive binary stars. The physics of core-collapse supernovae and the process of common envelope are two of the main sources of uncertainty about this formation channel. Alternatively, two black holes can form a binary by dynamical encounters in a dense star cluster. The dynamical formation channel leaves several imprints on the mass, spin and orbital properties of BBHs.
Son of X-Shooter (SOXS) will be a high-efficiency spectrograph with a mean Resolution-Slit product of 4500\sim 4500 (goal 5000) over the entire band capable of simultaneously observing the complete spectral range 350-2000 nm. It consists of three scientific arms (the UV-VIS Spectrograph, the NIR Spectrograph and the Acquisition Camera) connected by the Common Path system to the NTT and the Calibration Unit. The Common Path is the backbone of the instrument and the interface to the NTT Nasmyth focus flange. The light coming from the focus of the telescope is split by the common path optics into the two different optical paths in order to feed the two spectrographs and the acquisition camera. The instrument project went through the Preliminary Design Review in 2017 and is currently in Final Design Phase (with FDR in July 2018). This paper outlines the status of the Common Path system and is accompanied by a series of contributions describing the SOXS design and properties after the instrument Preliminary Design Review.
We use James Webb Space Telescope Near-Infrared Camera Wide Field Slitless Spectroscopy (NIRCam WFSS) and Near-Infrared spectrograph (NIRSpec) in the Cosmic Evolution Early Release survey (CEERS) to measure rest-frame optical emission-line of 155 galaxies at z>2. The blind NIRCam grism observations include a sample of galaxies with bright emission lines that were not observed on the NIRSpec masks. We study the changes of the Ha, [OIII]/Hb, and [NeIII]/[OII] emission lines in terms of redshift by comparing to lower redshift SDSS and CLEAR samples. We find a significant (>3σ\sigma) correlation between [OIII]/Hb with redshift, while [NeIII]/[OII] has a marginal (2σ\sigma) correlation with redshift. We compare [OIII]/Hb and [NeIII]/[OII] to stellar mass and Hb SFR. We find that both emission-line ratios have a correlation with Hb SFR and an anti-correlation with stellar mass across the redshifts 0
We present a comprehensive analysis of the evolution of the morphological and structural properties of a large sample of galaxies at z=3-9 using early JWST CEERS NIRCam observations. Our sample consists of 850 galaxies at z>3 detected in both CANDELS HST imaging and JWST CEERS NIRCam images to enable a comparison of HST and JWST morphologies. Our team conducted a set of visual classifications, with each galaxy in the sample classified by three different individuals. We also measure quantitative morphologies using the publicly available codes across all seven NIRCam filters. Using these measurements, we present the fraction of galaxies of each morphological type as a function of redshift. Overall, we find that galaxies at z>3 have a wide diversity of morphologies. Galaxies with disks make up a total of 60\% of galaxies at z=3 and this fraction drops to ~30% at z=6-9, while galaxies with spheroids make up ~30-40% across the whole redshift range and pure spheroids with no evidence for disks or irregular features make up ~20%. The fraction of galaxies with irregular features is roughly constant at all redshifts (~40-50%), while those that are purely irregular increases from ~12% to ~20% at z>4.5. We note that these are apparent fractions as many selection effects impact the visibility of morphological features at high redshift. The distributions of Sérsic index, size, and axis ratios show significant differences between the morphological groups. Spheroid Only galaxies have a higher Sérsic index, smaller size, and higher axis ratio than Disk/Irregular galaxies. Across all redshifts, smaller spheroid and disk galaxies tend to be rounder. Overall, these trends suggest that galaxies with established disks and spheroids exist across the full redshift range of this study and further work with large samples at higher redshift is needed to quantify when these features first formed.
We review the main physical processes that lead to the formation of stellar binary black holes (BBHs) and to their merger. BBHs can form from the isolated evolution of massive binary stars. The physics of core-collapse supernovae and the process of common envelope are two of the main sources of uncertainty about this formation channel. Alternatively, two black holes can form a binary by dynamical encounters in a dense star cluster. The dynamical formation channel leaves several imprints on the mass, spin and orbital properties of BBHs.
Next generation ground-based gravitational-wave detectors will observe binary black hole (BBH) mergers up to redshift z10z\gtrsim{}10, probing the evolution of compact binary (CB) mergers across cosmic time. Here, we present a new data-driven model to estimate the cosmic merger rate density (MRD) evolution of CBs, by coupling catalogs of CB mergers with observational constraints on the cosmic star formation rate density and on the metallicity evolution of the Universe. We adopt catalogs of CB mergers derived from recent NN-body and population-synthesis simulations, to describe the MRD of CBs formed in young star clusters (hereafter, dynamical CBs) and in the field (hereafter, isolated CBs). The local MRD of dynamical BBHs is RBBH=6420+34\mathcal{R}_{\rm BBH}=64^{+34}_{-20} Gpc3^{-3} yr1^{-1}, consistent with the 90% credible interval from the first and second observing run (O1 and O2) of the LIGO-Virgo collaboration, and with the local MRD of isolated BBHs (RBBH=5037+71\mathcal{R}_{\rm BBH}=50^{+71}_{-37} Gpc3^{-3} yr1^{-1}). The local MRD of dynamical and isolated black hole - neutron star binaries is RBHNS=4123+33\mathcal{R}_{\rm BHNS}=41^{+33}_{-23} and 4934+4849^{+48}_{-34}~Gpc3^{-3} yr1^{-1}, respectively. Both values are consistent with the upper limit inferred from O1 and O2. Finally, the local MRD of dynamical binary neutron stars (BNSs, RBNS=15138+59\mathcal{R}_{\rm BNS}=151^{+59}_{-38} Gpc3^{-3} yr1^{-1}) is a factor of two lower than the local MRD of isolated BNSs (RBNS=28375+97\mathcal{R}_{\rm BNS}=283^{+97}_{-75} Gpc3^{-3} yr1^{-1}). The MRD for all CB classes grows with redshift, reaching its maximum at $z \in [1.5,2.5]$, and then decreases. This trend springs from the interplay between cosmic star formation rate, metallicity evolution and delay time of binary compact objects.
We employed the {\it VISTA near-infrared YJKsYJK_\mathrm{s} survey of the Magellanic System} (VMC), to analyse the Y,J,KsY,\,J,\,K_\mathrm{s} light curves of δ\delta Cepheid stars (DCEPs) in the Large Magellanic Cloud (LMC). Our sample consists of 4408 objects accounting for 97 per cent of the combined list of OGLE\,IV and {\it Gaia}\,DR2 DCEPs. We determined a variety of period-luminosity (PLPL) and period-Wesenheit PWPW relationships for Fundamental (F) and First Overtone (1O) pulsators. We discovered for the first time a break in these relationships for 1O DCEPs at PP=0.58 d. We derived relative individual distances for DCEPs in the LMC with a precision of \sim1 kpc, calculating the position angle of the line of nodes and inclination of the galaxy: θ\theta=145.6±\pm1.0 deg and ii=25.7±\pm0.4 deg. The bar and the disc are seen under different viewing angles. We calculated the ages of the pulsators, finding two main episodes of DCEP formation lasting \sim40 Myr which happened 93 and 159 Myr ago. Likely as a result of its past interactions with the SMC, the LMC shows a non-planar distribution, with considerable structuring: the bar is divided into two distinct portions, the eastern and the western displaced by more than 1 kpc from each other. Similar behaviour is shown by the spiral arms. The LMC disc appears "flared" and thick, with a disc scale height of h0.97h\sim 0.97 kpc. This feature can be explained by strong tidal interactions with the Milky Way and/or the Small Magellanic Cloud or past merging events with now disrupted LMC satellites.
A wealth of extragalactic populations completely missed at UV-optical wavelengths has been identified in the last decade, combining the deepest HST and Spitzer observations. These dark sources are thought to be very dusty and star-forming systems at 3
We exploit the DustPedia sample of galaxies within approximately 40 Mpc, selecting 388 sources, to investigate the correlations between IR luminosity (LIR_{\rm IR}), the star formation rate (SFR), and the CO(1-0) luminosity (LCO_{\rm CO}) down to much lower luminosities than reached by previous analyses. We find a sub-linear dependence of the SFR on LIR_{\rm IR}. Below log(LIR/L)10\log(\hbox{L}_{\rm IR}/\hbox{L}_\odot)\simeq 10 or $\hbox{SFR}\simeq 1\,\hbox{M}_\odot\,\hbox{yr}^{-1},theSFR/L, the SFR/L_{\rm IR}$ ratio substantially exceeds the standard ratio for dust-enshrouded star formation, and the difference increases with decreasing LIR_{\rm IR} values. This implies that the effect of unobscured star formation overcomes that of dust heating by old stars, at variance with results based on the Planck\textit{Planck} ERCSC galaxy sample. We also find that the relations between the LCO_{\rm CO} and L$_{\rm IR}$ or the SFR are consistent with those obtained at much higher luminosities.
The spectral energy distribution (SED) of galaxies is essential for deriving fundamental properties like stellar mass and star formation history (SFH). However, conventional methods, including both parametric and non-parametric approaches, often fail to accurately recover the observed cosmic star formation rate (SFR) density due to oversimplified or unrealistic assumptions about SFH and their inability to account for the complex SFH variations across different galaxy populations. To address this issue, we introduce a novel approach that improves galaxy broadband SED analysis by incorporating physical priors derived from hydrodynamical simulations. Tests using IllustrisTNG simulations demonstrate that our method can reliably determine galaxy physical properties from broadband photometry, including stellar mass within 0.05 dex, current SFR within 0.3 dex, and fractional stellar formation time within 0.2 dex, with a negligible fraction of catastrophic failures. When applied to the Sloan Digital Sky Survey (SDSS) main photometric galaxy sample with spectroscopic redshift, our estimates of stellar mass and SFR are consistent with the widely used MPA-JHU and GSWLC catalogs. Notably, using the derived SFHs of individual SDSS galaxies, we estimate the cosmic SFR density and stellar mass density with remarkable consistency to direct observations up to z6z \sim 6. This demonstrates a significant advancement in deriving SFHs from SEDs that closely align with observational data. Consequently, our method can reliably recover observed spectral indices such as Dn(4000)\rm D_{\rm n}(4000) and $\rm H\delta_{\rm A}$ by synthesizing the full spectra of galaxies using the estimated SFHs and metal enrichment histories, relying solely on broadband photometry as input. Furthermore, this method is extremely computationally efficient compared to conventional approaches.
We present tests of a new method to simultaneously estimate stellar population and emission line (EL) properties of galaxies out of S-PLUS photometry. The technique uses the AlStar code, updated with an empirical prior which greatly improves its ability to estimate ELs using only the survey's 12 bands. The tests compare the output of (noise-perturbed) synthetic photometry of SDSS galaxies to properties derived from previous full spectral fitting and detailed EL analysis. For realistic signal-to-noise ratios, stellar population properties are recovered to better than 0.2 dex in masses, mean ages, metallicities and ±0.2\pm 0.2 mag for the extinction. More importantly, ELs are recovered remarkably well for a photometric survey. We obtain input - output dispersions of 0.05--0.2 dex for the equivalent widths of [OII][\mathrm{O}\,\rm{II}], [OIII][\mathrm{O}\,\rm{III}], Hβ\beta, Hα\alpha, [NII][\mathrm{N}\,\rm{II}], and [SII][\mathrm{S}\,\rm{II}], and even better for lines stronger than 5\sim 5 A˚\mathring{A}. These excellent results are achieved by combining two empirical facts into a prior which restricts the EL space available for the fits: (1) Because, for the redshifts explored here, Hα\alpha and [NII][\mathrm{N}\,\rm{II}] fall in a single narrow band (J0660), their combined equivalent width is always well recovered, even when [NII][\mathrm{N}\,\rm{II}]/Hα\alpha is not. (2) We know from SDSS that WHα+[NII]W_{H\alpha+[\mathrm{N}\,\rm{II}]} correlates with [NII][\mathrm{N}\,\rm{II}]/Hα\alpha, which can be used to tell if a galaxy belongs to the left or right wings in the classical BPT diagnostic diagram. Example applications to integrated light and spatially resolved data are also presented, including a comparison with independent results obtained with MUSE-based integral field spectroscopy.
We report the discovery of ancient massive merger events in the early-type galaxies NGC 1380 and NGC 1427, members of the Fornax galaxy cluster. Both galaxies have been observed by the MUSE IFU instrument on the VLT, as part of the Fornax3D project. By fitting recently-developed population-orbital superposition models to the observed surface brightness as well as stellar kinematic, age, and metallicity maps, we obtain the stellar orbits, age and metallicity distributions of each galaxy. We then decompose each galaxy into multiple orbital-based components, including a dynamically hot inner stellar halo component which is identified as the relic of past massive mergers. By comparing to analogues from cosmological galaxy simulations, chiefly TNG50, we find that the formation of such a hot inner stellar halo requires the merger with a now-destroyed massive satellite galaxy of 3.71.5+2.7×10103.7_{-1.5}^{+2.7} \times 10^{10} Msun (about 1/51/5 of its current stellar mass) in the case of NGC 1380 and of 1.50.7+1.6×10101.5_{-0.7}^{+1.6} \times10^{10} Msun (about 1/41/4 of its current stellar mass) in the case of NGC 1427. Moreover, we infer that the last massive merger in NGC 1380 happened 10\sim10 Gyr ago based on the stellar age distribution of the re-grown dynamically cold disk, whereas the merger in NGC 1427 ended t8t\lesssim 8 Gyr ago based on the stellar populations in its hot inner stellar halo. The major merger event in NGC 1380 is the first one with both merger mass and merger time quantitatively inferred in a galaxy beyond the Local Volume. Moreover, it is the oldest and most massive merger uncovered in nearby galaxies so far.
We use data from the Herschel-ATLAS to investigate the evolution of the far-infrared--radio correlation over the redshift range 05sigma sources in the Herschel-ATLAS Science Demonstration Field and cross-matching these data with radio data from the Faint Images of the Radio Sky at Twenty-Centimetres (FIRST) survey and the NRAO VLA Northern Sky Survey (NVSS), we obtain 104 radio counterparts to the Herschel sources. With these data we find no evidence for evolution in the far-infrared--radio correlation over the redshift range 0
The first detection of a binary neutron star merger through gravitational waves and photons marked the dawn of multi-messenger astronomy with gravitational waves, and it greatly increased our insight in different fields of astrophysics and fundamental physics. However, many open questions on the physical process involved in a compact binary merger still remain and many of these processes concern plasma physics. With the second generation of gravitational wave interferometers approaching their design sensitivity, the new generation under design study, and new X-ray detectors under development, the high energy Universe will become more and more a unique laboratory for our understanding of plasma in extreme conditions. In this review, we discuss the main electromagnetic signals expected to follow the merger of two compact objects highlighting the main physical processes involved and some of the most important open problems in the field.
Hierarchical mergers are one of the distinctive signatures of binary black hole (BBH) formation through dynamical evolution. Here, we present a fast semi-analytic approach to simulate hierarchical mergers in nuclear star clusters (NSCs), globular clusters (GCs) and young star clusters (YSCs). Hierarchical mergers are more common in NSCs than they are in both GCs and YSCs, because of the different escape velocity. The mass distribution of hierarchical BBHs strongly depends on the properties of first-generation BBHs, such as their progenitor's metallicity. In our fiducial model, we form black holes (BHs) with masses up to 103\sim{}10^3 M_\odot in NSCs and up to 102\sim{}10^2 M_\odot in both GCs and YSCs. When escape velocities in excess of 100 km~s1^{-1} are considered, BHs with mass >103>10^3 M_\odot are allowed to form in NSCs. Hierarchical mergers lead to the formation of BHs in the pair instability mass gap and intermediate-mass BHs, but only in metal-poor environments. The local BBH merger rate in our models ranges from 10\sim{}10 to 60\sim{} 60 Gpc3^{-3} yr1^{-1}; hierarchical BBHs in NSCs account for 1020.2\sim{}10^{-2}- 0.2 Gpc3^{-3} yr1^{-1}, with a strong upper limit of 10\sim{}10 Gpc3^{-3} yr1^{-1}. When comparing our models with the second gravitational-wave transient catalog, we find that multiple formation channels are favored to reproduce the observed BBH population.
We present the Tiered Radio Extragalactic Continuum Simulation (T-RECS): a new simulation of the radio sky in continuum, over the 150 MHz-20 GHz range. T-RECS models two main populations of radio galaxies: Active Galactic Nuclei (AGNs) and Star-Forming Galaxies (SFGs), and corresponding sub-populations. Our model also includes polarized emission over the full frequency range, which has been characterised statistically for each population using the available information. We model the clustering properties in terms of probability distributions of hosting halo masses, and use lightcones extracted from a high-resolution cosmological simulation to determine the positions of haloes. This limits the sky area for the simulations including clustering to a 25deg2 field of view. We compare luminosity functions, number counts in total intensity and polarization, and clustering properties of our outputs to up-to-date compilations of data and find a very good agreement. We deliver a set of simulated catalogues, as well as the code to produce them, which can be used for simulating observations and predicting results from deep radio surveys with existing and forthcoming radio facilities, such as the Square Kilometre Array (SKA).
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