J-PLUS: On the identification of new cluster members in the double galaxy cluster A2589 and A2593 using PDFs

Publication date: 
Main author: 
Molino, A.
IAA authors: 
Molino, A.;Sampedro, L.;Benítez, N.
Molino, A.;Costa-Duarte, M. V.;Mendes de Oliveira, C.;Cenarro, A. J.;Lima Neto, G. B.;Cypriano, E. S.;Sodré, L.;Coelho, P.;Chow-Martínez, M.;Monteiro-Oliveira, R.;Sampedro, L.;Cristobal-Hornillos, D.;Varela, J.;Ederoclite, A.;Chies-Santos, A. L.;Schoenell, W.;Ribeiro, T.;Marín-Franch, A.;López-Sanjuan, C.;Hernández-Fernández, J. D.;Cortesi, A.;Vázquez Ramió, H.;Santos, W.;Cibirka, N.;Novais, P.;Pereira, E.;Hernández-Jimenez, J. A.;Jimenez-Teja, Y.;Moles, M.;Benítez, N.;Dupke, R.
Astronomy and Astrophysics
Publication type: 
<BR /> 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) &amp; A2593 (z = 0.0440), using redshift probability distribution functions (PDFs). The ultimate goal is to demonstrate the usefulness of a 12-band filter system in the study of largescale structure in the local Universe. <BR /> 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. <BR /> 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 photometric-depth of r 21.5 provides δ<SUB>z</SUB>/(1 + z) = 0.01 photo-z estimates. A precision of δ<SUB>z</SUB>/(1 + z) = 0.005 is obtained for the 177 galaxies brighter than magnitude r &lt; 17. Based on simulations, a δ<SUB>z</SUB>/(1 + z) = 0.02 and δ<SUB>z</SUB>/(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 ( 5 deg<SUP>2</SUP>). 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. <BR /> 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.
ADS Bibcode: 
large-scale structure of Universe;galaxies: distances and redshifts;galaxies: photometry;galaxies: clusters: general;surveys;Astrophysics - Cosmology and Nongalactic Astrophysics;Astrophysics - Astrophysics of Galaxies