The Southern Photometric Local Universe Survey (S-PLUS) is imaging ∼9300 deg2 of the celestial sphere in 12 optical bands using a dedicated 0.8 m robotic telescope, the T80-South, at the Cerro Tololo Inter-american Observatory, Chile. The telescope is equipped with a 9.2k × 9.2k e2v detector with 10 $\rm {\mu m}$ pixels, resulting in a field of view of 2 deg2 with a plate scale of 0.55 arcsec pixel−1. The survey consists of four main subfields, which include two non-contiguous fields at high Galactic latitudes (|b| > 30°, 8000 deg2) and two areas of the Galactic Disc and Bulge (for an additional 1300 deg2). S-PLUS uses the Javalambre 12-band magnitude system, which includes the 5 ugriz broad-band filters and 7 narrow-band filters centred on prominent stellar spectral features: the Balmer jump/[OII], Ca H + K, H δ, G band, Mg b triplet, H α, and the Ca triplet. S-PLUS delivers accurate photometric redshifts (δz/(1 + z) = 0.02 or better) for galaxies with r < 19.7 AB mag and z < 0.4, thus producing a 3D map of the local Universe over a volume of more than $1\, (\mathrm{Gpc}/h)^3$. The final S-PLUS catalogue will also enable the study of star formation and stellar populations in and around the Milky Way and nearby galaxies, as well as searches for quasars, variable sources, and low-metallicity stars. In this paper we introduce the main characteristics of the survey, illustrated with science verification data highlighting the unique capabilities of S-PLUS. We also present the first public data release of ∼336 deg2 of the Stripe 82 area, in 12 bands, to a limiting magnitude of r = 21, available at datalab.noao.edu/splus.

In this work, we consider the stochastic background of gravitational waves (SBGWs) produced by pre‐galactic stars, which form black holes in scenarios of structure formation. The calculation is performed in the framework of hierarchical structure formation using a Press–Schechter‐like formalism. Our model reproduces the observed star formation rate at redshifts z≲ 6.5. The signal predicted in this work is below the sensitivity of the first generation of detectors but could be detectable by the next generation of ground‐based interferometers. Specifically, correlating two coincident advanced Laser Interferometer Gravitational‐Wave Observatory (LIGO) detectors (LIGO III interferometers), the expected signal‐to‐noise ratio (S/N) could be as high as 90 (10) for stars forming at redshift z≃ 20 with a Salpeter initial mass function with slope x= 0.35 (1.35), and if the efficiency of generation of gravitational waves, namely, εGW is close to the maximum value ∼7 × 10−4. However, the sensitivity of the future third generation of detectors as, for example, the European antenna EGO could be high enough to produce S/N > 3 same with εGW∼ 2 × 10−5. We also discuss what astrophysical information could be derived from a positive (or even negative) detection of the SBGWs investigated here.

We present the first systematic study of the stellar populations of ultra-diffuse galaxies (UDGs) in the field, integrating the large area search and characterization of UDGs by the SMUDGes survey with the twelve-band optical photometry of the S-PLUS survey. Based on Bayesian modeling of the optical colors of UDGs, we determine the ages, metallicities and stellar masses of 100 UDGs distributed in an area of ∼ 330 deg 2 in the Stripe 82 region. We find that the stellar masses and metallicities of field UDGs are similar to those observed in clusters and follow the trends previously defined in studies of dwarf and giant galaxies. However, field UDGs have younger luminosityweighted ages than do UDGs in clusters. We interpret this result to mean that field UDGs have more extended star formation histories, including some that continue to form stars at low levels to the present time. Finally, we examine stellar population 2 Barbosa et al.scaling relations that show that UDGs are, as a population, similar to other low-surface brightness galaxies.

In this paper we present a thorough discussion about the photometric redshift (photo-z) performance of the Southern Photometric Local Universe Survey (S-PLUS). This survey combines a 7 narrow + 5 broad passband filter system, with a typical photometric-depth of r∼21 AB. For this exercise, we utilize the Data Release 1 (DR1), corresponding to 336 deg2 from the Stripe-82 region. We rely on the BPZ2 code to compute our estimates, using a new library of SED models, which includes additional templates for quiescent galaxies. When compared to a spectroscopic redshift control sample of ∼100k galaxies, we find a precision of σz &lt;0.8%, &lt;2.0% or &lt;3.0% for galaxies with magnitudes r&lt;17, &lt;19 and &lt;21, respectively. A precision of 0.6% is attained for galaxies with the highest Odds values. These estimates have a negligible bias and a fraction of catastrophic outliers inferior to 1%. We identify a redshift window (i.e., 0.26&lt;z &lt;0.32) where our estimates double their precision, due to the simultaneous detection of two emission-lines in two distinct narrow-bands; representing a window opportunity to conduct statistical studies such as luminosity functions. We forecast a total of ∼2M, ∼16M and ∼32M galaxies in the S-PLUS survey with a photo-z precision of σz &lt;1.0%, &lt;2.0% and &lt;2.5% after observing 8000 deg2. We also derive redshift Probability Density Functions, proving their reliability encoding redshift uncertainties and their potential recovering the n(z) of galaxies at z &lt; 0.4, with an unprecedented precision for a photometric survey in the southern hemisphere.

Aims. We aim to use multiband imaging from the Phase-3 Verification Data of the J-PLUS survey to derive accurate photometric redshifts (photo-z) and look for potential new members in the surroundings of the nearby galaxy clusters A2589 (z=0.0414) & A2593 (z=0.0440), using redshift probability distribution functions (PDF). The ultimate goal is to demonstrate the usefulness of a 12-band filter system in the study of largescale structure in the local universe. Methods. We present an optimized pipeline for the estimation of photometric redshifts in clusters of galaxies. This pipeline includes a PSF-corrected photometry, specific photometric apertures capable of enhancing the integrated signal in the bluest filters, a careful recalibration of the photometric uncertainties and accurate upper-limit estimations for faint detections. To foresee the expected precision of our photo-z beyond the spectroscopic sample, we designed a set of simulations in which real cluster galaxies are modeled and reinjected inside the images at different signal-to-noise ratio (S/N) levels, recomputing their photometry and photo-z estimates. Results. We tested our photo-z pipeline with a sample of 296 spectroscopically confirmed cluster members with an averaged magnitude of < r >= 16.6 and redshift < z >=0.041. The combination of seven narrow and five broadband filters with a typical photometricdepth of r ∼ 21.5 provides δ z /(1+z)=0.01 photo-z estimates. A precision of δ z /(1+z)=0.005 is obtained for the 177 galaxies brighter than magnitude r <17. Based on simulations, a δ z /(1+z)=0.02 and δ z /(1+z)=0.03 is expected at magnitudes < r >= 18 and < r >= 22, respectively. Complementarily, we used SDSS/DR12 data to derive photo-z estimates for the same galaxy sample. This exercise demonstrates that the wavelength-resolution of the J-PLUS data can double the precision achieved by SDSS data for galaxies with a high S/N. Based on the Bayesian membership analysis carried out in this work, we find as much as 170 new candidates across the entire field (∼5deg 2 ). The spatial distribution of these galaxies may suggest an overlap between the systems with no evidence of a clear filamentary structure connecting the clusters. This result is supported by X-ray Rosat All-Sky Survey observations suggesting that a hypothetical filament may have low density contrast on diffuse warm gas. Conclusions. We prove that the addition of the seven narrow-band filters make the J-PLUS data deeper in terms of photo-z-depth than other surveys of a similar photometric-depth but using only five broadbands. These preliminary results show the potential of J-PLUS data to revisit membership of groups and clusters from nearby galaxies, important for the determination of luminosity and mass functions and environmental studies at the intermediate and low-mass regime.