We present a star/galaxy classification for the Southern Photometric Local Universe Survey (S-PLUS), based on a Machine Learning approach: the Random Forest algorithm. We train the algorithm using ...the S-PLUS optical photometry up to \(r\)=21, matched to SDSS/DR13, and morphological parameters. The metric of importance is defined as the relative decrease of the initial accuracy when all correlations related to a certain feature is vanished. In general, the broad photometric bands presented higher importance when compared to narrow ones. The influence of the morphological parameters has been evaluated training the RF with and without the inclusion of morphological parameters, presenting accuracy values of 95.0\% and 88.1\%, respectively. Particularly, the morphological parameter {\rm FWHM/PSF} performed the highest importance over all features to distinguish between stars and galaxies, indicating that it is crucial to classify objects into stars and galaxies. We investigate the misclassification of stars and galaxies in the broad-band colour-colour diagram \((g-r)\) versus \((r-i)\). The morphology can notably improve the classification of objects at regions in the diagram where the misclassification was relatively high. Consequently, it provides cleaner samples for statistical studies. The expected contamination rate of red galaxies as a function of the redshift is estimated, providing corrections for red galaxy samples. The classification of QSOs as extragalactic objects is slightly better using photometric-only case. An extragalactic point-source catalogue is provided using the classification without any morphology feature (only the SED information) with additional constraints on photometric redshifts and {\rm FWHM/PSF} values.
We use the SDSS and WISE surveys to investigate the real nature of galaxies defined as LINERs in the BPT diagram. After establishing a mid-infrared colour W2-W3 = 2.5 as the optimal separator between ...galaxies with and without star formation, we investigate the loci of different galaxy classes in the W_{Ha} versus W2-W3 space. We find that: (1) A large fraction of LINER-like galaxies are emission-line retired galaxies, i.e galaxies which have stopped forming stars and are powered by hot low-mass evolved stars (HOLMES). Their W2-W3 colours show no sign of star formation and their Ha equivalent widths, W_{Ha}, are consistent with ionization by their old stellar populations. (2) Another important fraction have W2-W3 indicative of star formation. This includes objects located in the supposedly `pure AGN' zone of the BPT diagram. (3) A smaller fraction of LINER-like galaxies have no trace of star formation from W2-W3 and a high W_{Ha}, pointing to the presence of an AGN. (4) Finally, a few LINERs tagged as retired by their W_{Ha} but with W2-W3 values indicative of star formation are late-type galaxies whose SDSS spectra cover only the old `retired' bulge. This reinforces the view that LINER-like galaxies are a mixed bag of objects involving different physical phenomena and observational effects thrusted into the same locus of the BPT diagram.
The Fornax Cluster through S-PLUS Smith Castelli, A V; Mendes de Oliveira, C; Herpich, F ...
arXiv.org,
04/2021
Paper, Journal Article
Odprti dostop
The Southern Photometric Local Universe Survey (S-PLUS) aims to map \(\approx\) 9300 deg\(^2\) of the Southern sky using the Javalambre filter system of 12 optical bands, 5 Sloan-like filters and 7 ...narrow-band filters centered on several prominent stellar features (OII, Ca H+K, D4000, H\(_{\delta}\), Mgb, H\(_{\alpha}\) and CaT). S-PLUS is carried out with the T80-South, a new robotic 0.826-m telescope located on CTIO, equipped with a wide FoV camera (2 deg\(^2\)). In this poster we introduce project #59 of the S-PLUS collaboration aimed at studying the Fornax galaxy cluster covering an sky area of \(\approx\) 11 \(\times\) 7 deg\(^2\), and with homogeneous photometry in the 12 optical bands of S-PLUS (Coordinator: A. Smith Castelli).
We report the results of two multi-chord stellar occultations by the dwarf planet (1) Ceres that were observed from Brazil on 2010 August 17, and from the USA on 2013 October 25. Four positive ...detections were obtained for the 2010 occultation, and nine for the 2013 occultation. Elliptical models were adjusted to the observed chords to obtain Ceres' size and shape. Two limb fitting solutions were studied for each event. The first one is a nominal solution with an indeterminate polar aspect angle. The second one was constrained by the pole coordinates as given by Drummond et al. Assuming a Maclaurin spheroid, we determine an equatorial diameter of 972 \(\pm\) 6 km and an apparent oblateness of 0.08 \(\pm\) 0.03 as our best solution. These results are compared to all available size and shape determinations for Ceres made so far, and shall be confirmed by the NASA's Dawn space mission.
The Southern Photometric Local Universe Survey (S-PLUS) is an ongoing survey
of $\sim$9300 deg$^2$ in the southern sky in a 12-band photometric system. This
paper presents the second data release ...(DR2) of S-PLUS, consisting of 514 tiles
covering an area of 950 deg$^2$. The data has been fully calibrated using a new
photometric calibration technique suitable for the new generation of wide-field
multi-filter surveys. This technique consists of a $\chi^2$ minimisation to fit
synthetic stellar templates to already calibrated data from other surveys,
eliminating the need for standard stars and reducing the survey duration by
$\sim$15\%. We compare the template-predicted and S-PLUS instrumental
magnitudes to derive the photometric zero-points (ZPs). We show that these ZPs
can be further refined by fitting the stellar templates to the 12 S-PLUS
magnitudes, which better constrain the models by adding the narrow-band
information. We use the STRIPE82 region to estimate ZP errors, which are
$\lesssim10$ mmags for filters J0410, J0430, $g$, J0515, $r$, J0660, $i$, J0861
and $z$; $\lesssim 15$ mmags for filter J0378; and $\lesssim 25$ mmags for
filters $u$ and J0395. We describe the complete data flow of the S-PLUS/DR2
from observations to the final catalogues and present a brief characterisation
of the data. We show that, for a minimum signal-to-noise threshold of 3, the
photometric depths of the DR2 range from 19.9 mag to 21.3 mag (measured in
Petrosian apertures), depending on the filter. The S-PLUS DR2 can be accessed
from the website: https://splus.cloud}{https://splus.cloud.
The Southern Photometric Local Universe Survey (S-PLUS) is imaging ~9300 deg^2 of the celestial sphere in twelve 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 by 9.2k e2v detector with 10 um pixels, resulting in a field-of-view of 2 deg^2 with a plate scale of 0.55"/pixel. The survey consists of four main subfields, which include two non-contiguous fields at high Galactic latitudes (8000 deg^2 at |b| > 30 deg) and two areas of the Galactic plane and bulge (for an additional 1300 deg^2). S-PLUS uses the Javalambre 12-band magnitude system, which includes the 5 u, g, r, i, z broad-band filters and 7 narrow-band filters centered on prominent stellar spectral features: the Balmer jump/OII, Ca H+K, H-delta, G-band, Mg b triplet, H-alpha, and the Ca triplet. S-PLUS delivers accurate photometric redshifts (delta_z/(1+z) = 0.02 or better) for galaxies with r < 20 AB mag and redshift < 0.5, thus producing a 3D map of the local Universe over a volume of more than 1 (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 deg^2 of the Stripe-82 area, which is available at http://datalab.noao.edu/splus.
The Southern Photometric Local Universe Survey (S-PLUS) is an ongoing survey of \(\sim\)9300 deg\(^2\) in the southern sky in a 12-band photometric system. This paper presents the second data release ...(DR2) of S-PLUS, consisting of 514 tiles covering an area of 950 deg\(^2\). The data has been fully calibrated using a new photometric calibration technique suitable for the new generation of wide-field multi-filter surveys. This technique consists of a \(\chi^2\) minimisation to fit synthetic stellar templates to already calibrated data from other surveys, eliminating the need for standard stars and reducing the survey duration by \(\sim\)15\%. We compare the template-predicted and S-PLUS instrumental magnitudes to derive the photometric zero-points (ZPs). We show that these ZPs can be further refined by fitting the stellar templates to the 12 S-PLUS magnitudes, which better constrain the models by adding the narrow-band information. We use the STRIPE82 region to estimate ZP errors, which are \(\lesssim10\) mmags for filters J0410, J0430, \(g\), J0515, \(r\), J0660, \(i\), J0861 and \(z\); \(\lesssim 15\) mmags for filter J0378; and \(\lesssim 25\) mmags for filters \(u\) and J0395. We describe the complete data flow of the S-PLUS/DR2 from observations to the final catalogues and present a brief characterisation of the data. We show that, for a minimum signal-to-noise threshold of 3, the photometric depths of the DR2 range from 19.9 mag to 21.3 mag (measured in Petrosian apertures), depending on the filter. The S-PLUS DR2 can be accessed from the website: https://splus.cloud}{https://splus.cloud.
The Southern Photometric Local Universe Survey (S-PLUS) is a project to map
$\sim9300$ sq deg of the sky using twelve bands (seven narrow and five
broadbands). Observations are performed with the ...T80-South telescope, a robotic
telescope located at the Cerro Tololo Observatory in Chile. The survey
footprint consists of several large contiguous areas, including fields at high
and low galactic latitudes, and towards the Magellanic Clouds. S-PLUS uses
fixed exposure times to reach point source depths of about $21$ mag in the
$griz$ and $20$ mag in the $u$ and the narrow filters. This paper describes the
S-PLUS Data Release 4 (DR4), which includes calibrated images and derived
catalogues for over 3000 sq deg, covering the aforementioned area. The
catalogues provide multi-band photometry performed with the tools
\texttt{DoPHOT} and \texttt{SExtractor} -- point spread function (\PSF) and
aperture photometry, respectively. In addition to the characterization, we also
present the scientific potential of the data. We use statistical tools to
present and compare the photometry obtained through different methods. Overall
we find good agreement between the different methods, with a slight systematic
offset of 0.05\,mag between our \PSF and aperture photometry. We show that the
astrometry accuracy is equivalent to that obtained in previous S-PLUS data
releases, even in very crowded fields where photometric extraction is
challenging. The depths of main survey (MS) photometry for a minimum
signal-to-noise ratio $S/N = 3$ reach from $\sim19.5$ for the bluer bands to
$\sim21.5$ mag on the red. The range of magnitudes over which accurate \PSF
photometry is obtained is shallower, reaching $\sim19$ to $\sim20.5$ mag
depending on the filter. Based on these photometric data, we provide
star-galaxy-quasar classification and photometric redshift for millions of
objects.
Early-type retired galaxies (RGs, i.e. galaxies which no longer form stars) can be divided into two classes: those with no emission lines, here dubbed lineless RGs, and those with emission lines, ...dubbed liny RGs. Both types of galaxies contain hot low-mass evolved stars (HOLMES) which emit ionizing photons. The difference must thus lie in the presence or absence of a reservoir of ionizable gas. From a volume-limited sample of 38\,038 elliptical galaxies, we explore differences in physical properties between liny and lineless using data from the SDSS, WISE and GALEX catalogues. To avoid biases in the comparison, we pair-match liny and lineless in stellar-mass, redshift and half-light Petrosian radius. We detect marginal differences in their optical stellar ages and NUV luminosities, indicating that liny RGs have an excess of intermediate-age (0.1--5 Gyr) stellar populations. Liny RGs show higher dust attenuation and \(W3\) luminosities than their lineless counterparts. We also find that the amount of warm gas needed to explain the observed \Ha luminosity in liny RGs is \(10^5\)--\(10^8\)\msun, and that their \nii/\oii emission-line ratios are typical of those of the most massive star-forming galaxies. Taken together, these results rules out the following sources for the warm gas in liny RGs: mass-loss from intermediate-mass stars, mergers with metal-poor galaxies and intergalactic streams. They imply instead an inflow of enriched gas previously expelled from the galaxy or a merger with a metal-rich galaxy. The ionization source and the origin of the gas producing the emission lines are thus disconnected.
The Southern Photometric Local Universe Survey (S-PLUS) is a project to map \(\sim9300\) sq deg of the sky using twelve bands (seven narrow and five broadbands). Observations are performed with the ...T80-South telescope, a robotic telescope located at the Cerro Tololo Observatory in Chile. The survey footprint consists of several large contiguous areas, including fields at high and low galactic latitudes, and towards the Magellanic Clouds. S-PLUS uses fixed exposure times to reach point source depths of about \(21\) mag in the \(griz\) and \(20\) mag in the \(u\) and the narrow filters. This paper describes the S-PLUS Data Release 4 (DR4), which includes calibrated images and derived catalogues for over 3000 sq deg, covering the aforementioned area. The catalogues provide multi-band photometry performed with the tools \texttt{DoPHOT} and \texttt{SExtractor} -- point spread function (\PSF) and aperture photometry, respectively. In addition to the characterization, we also present the scientific potential of the data. We use statistical tools to present and compare the photometry obtained through different methods. Overall we find good agreement between the different methods, with a slight systematic offset of 0.05\,mag between our \PSF and aperture photometry. We show that the astrometry accuracy is equivalent to that obtained in previous S-PLUS data releases, even in very crowded fields where photometric extraction is challenging. The depths of main survey (MS) photometry for a minimum signal-to-noise ratio \(S/N = 3\) reach from \(\sim19.5\) for the bluer bands to \(\sim21.5\) mag on the red. The range of magnitudes over which accurate \PSF photometry is obtained is shallower, reaching \(\sim19\) to \(\sim20.5\) mag depending on the filter. Based on these photometric data, we provide star-galaxy-quasar classification and photometric redshift for millions of objects.
