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Register a new userGLACE survey: galaxy activity in ZwCl0024+1652 cluster from strong optical emission lines
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Zeleke Beyoro-Amado
Publication date
2020
fields
Physics
and research's language is
English
Authors
Zeleke Beyoro-Amado
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Although ZwCl0024+1652 galaxy cluster at $zsim0.4$ has been thoroughly analysed, it lacks a comprehensive study of star formation and nuclear activity of its members. With GaLAxy Cluster Evolution (GLACE) survey, a total of 174 H$alpha$ emission-line galaxies (ELGs) were detected, most of them having [NII}]. We reduced and analysed a set of [OIII] and H$beta$ tunable filter (TF) observations within GLACE survey. Using H$alpha$ priors, we identified [OIII] and H$beta$ in 35 ($sim$20%) and 59 ($sim$34%) sources, respectively, with 21 of them having both emission lines, and 20 having in addition [NII]. Applying BPT-NII diagnostic diagram, we classified these ELGs into 40% star-forming (SF), 55% composites, and 5% LINERs. Star formation rate (SFR) measured through extinction corrected H$alpha$ fluxes increases with stellar mass ($mathrm{M}_{*}$), attaining its peak at $mathrm{M}_{*}sim10^{9.8}mathrm{M}_odot$. We observed that the cluster centre to $sim$1.3Mpc is devoid of SF galaxies and AGN. Our results suggest that the star formation efficiency declines as the local density increases in the cluster medium. Moreover, the SF and AGN fractions drop sharply towards high-density environments. We observed a strong decline in SF fraction in high $mathrm{M}_*$, confirming that star formation is highly suppressed in high-mass cluster galaxies. Finally, we determined that SFR correlates with $mathrm{M}_*$ while specific SFR (sSFR) anti-correlates with $mathrm{M}_*$, both for cluster and field. This work shows the importance and strength of TF observations when studying ELGs in clusters at higher redshifts. We provide with this paper a catalogue of ELGs with H$beta$ and/or [OIII] lines in ZwCl0024+1652 cluster.
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The cores of clusters at 0 $lesssim$ z $lesssim$ 1 are dominated by quiescent early-type galaxies, whereas the field is dominated by star-forming late-type ones. Galaxy properties, notably the star formation (SF) ability, are altered as they fall into overdense regions. The critical issues to understand this evolution are how the truncation of SF is connected to the morphological transformation and the responsible physical mechanism. The GaLAxy Cluster Evolution Survey (GLACE) is conducting a study on the variation of galaxy properties (SF, AGN, morphology) as a function of environment in a representative sample of clusters. A deep survey of emission line galaxies (ELG) is being performed, mapping a set of optical lines ([OII], [OIII], H$beta$ and H$alpha$/[NII]) in several clusters at z $sim$ 0.40, 0.63 and 0.86. Using the Tunable Filters (TF) of OSIRIS/GTC, GLACE applies the technique of TF tomography: for each line, a set of images at different wavelengths are taken through the TF, to cover a rest frame velocity range of several thousands km/s. The first GLACE results target the H$alpha$/[NII] lines in the cluster ZwCl 0024.0+1652 at z = 0.395 covering $sim$ 2 $times$ r$_{vir}$. We discuss the techniques devised to process the TF tomography observations to generate the catalogue of H$alpha$ emitters of 174 unique cluster sources down to a SFR below 1 M$_{odot}$/yr. The AGN population is discriminated using different diagnostics and found to be $sim$ 37% of the ELG population. The median SFR is 1.4 M$_{odot}$/yr. We have studied the spatial distribution of ELG, confirming the existence of two components in the redshift space. Finally, we have exploited the outstanding spectral resolution of the TF to estimate the cluster mass from ELG dynamics, finding M$_{200}$ = 4.1 $times$ 10$^{14}$ M$_{odot} h^{-1}$, in agreement with previous weak-lensing estimates.
Aimed at understanding the evolution of galaxies in clusters, the GLACE survey is mapping a set of optical lines ([OII]3727, [OIII]5007, Hbeta and Halpha/[NII] when possible) in several galaxy clusters at redshift around 0.40, 0.63 and 0.86, using the Tuneable Filters (TF) of the OSIRIS instrument (Cepa et al. 2005) at the 10.4m GTC telescope. This study will address key questions about the physical processes acting upon the infalling galaxies during the course of hierarchical growth of clusters. GLACE is already ongoing: we present some preliminary results on our observations of the galaxy cluster Cl0024+1654 at z = 0.395; on the other hand, [email protected] has been approved as ESO/GTC large project to be started in 2011.
Strong gravitational lensing by galaxy clusters magnifies background galaxies, enhancing our ability to discover statistically significant samples of galaxies at z>6, in order to constrain the high-redshift galaxy luminosity functions. Here, we present the first five lens models out of the Reionization Lensing Cluster Survey (RELICS) Hubble Treasury Program, based on new HST WFC3/IR and ACS imaging of the clusters RXC J0142.9+4438, Abell 2537, Abell 2163, RXC J2211.7-0349, and ACT-CLJ0102-49151. The derived lensing magnification is essential for estimating the intrinsic properties of high-redshift galaxy candidates, and properly accounting for the survey volume. We report on new spectroscopic redshifts of multiply imaged lensed galaxies behind these clusters, which are used as constraints, and detail our strategy to reduce systematic uncertainties due to lack of spectroscopic information. In addition, we quantify the uncertainty on the lensing magnification due to statistical and systematic errors related to the lens modeling process, and find that in all but one cluster, the magnification is constrained to better than 20% in at least 80% of the field of view, including statistical and systematic uncertainties. The five clusters presented in this paper span the range of masses and redshifts of the clusters in the RELICS program. We find that they exhibit similar strong lensing efficiencies to the clusters targeted by the Hubble Frontier Fields within the WFC3/IR field of view. Outputs of the lens models are made available to the community through the Mikulski Archive for Space Telescopes
We present observations from the Gaia-ESO Survey in the lines of H$alpha$, [N II], [S II] and He I of nebular emission in the central part of the Carina Nebula. We investigate the properties of the two already known kinematic components (approaching and receding, respectively), which account for the bulk of emission. Moreover, we investigate the features of the much less known low-intensity high-velocity (absolute RV $>$50 km/s) gas emission. We show that gas giving rise to H$alpha$ and He I emission is dynamically well correlated, but not identical, to gas seen through forbidden-line emission. Gas temperatures are derived from line-width ratios, and densities from [S II] doublet ratios. The spatial variation of N ionization is also studied, and found to differ between the approaching and receding components. The main result is that the bulk of the emission lines in the central part of Carina arises from several distinct shell-like expanding regions, the most evident found around $eta$ Car, the Trumpler 14 core, and the star WR25. Such shells are non-spherical, and show distortions probably caused by collisions with other shells or colder, higher-density gas. Part of them is also obscured by foreground dust lanes, while only very little dust is found in their interior. Preferential directions, parallel to the dark dust lanes, are found in the shell geometries and physical properties, probably related to strong density gradients in the studied region. We also find evidence that the ionizing flux emerging from $eta$ Car and the surrounding Homunculus nebula varies with polar angle. The high-velocity components in the wings of H$alpha$ are found to arise from expanding dust reflecting the $eta$ Car spectrum.
Studying the transformation of cluster galaxies contributes a lot to have a clear picture of evolution of the universe. Towards that we are studying different properties (morphology, star formation, AGN contribution and metallicity) of galaxies in clusters up to $zsim1.0$ taking three different clusters: ZwCl0024+1652 at $zsim0.4$, RXJ1257+4738 at $zsim0.9$ and Virgo at $zsim0.0038$. For ZwCl0024+1652 and RXJ1257+4738 clusters we used tunable filters data from GLACE survey taken with GTC 10.4 m telescope and other public data, while for Virgo we used public data. We did the morphological classification of 180 galaxies in ZwCl0024+1652 using galSVM, where 54% and 46% of galaxies were classified as early-type (ET) and late-type (LT) respectively. We did a comparison between the three clusters within the clustercentric distance of 1Mpc and found that ET proportion (decreasing with redshift) dominates over the LT (increasing with redshift) throughout. We finalized the data reduction for ZwCl0024+1652 cluster and identified 46 [OIII] and 73 H$beta$ emission lines. For this cluster we have classified 22 emission line galaxies (ELGs) using BPT-NII diagnostic diagram resulting with 14 composite, 1 AGN and 7 star forming (SF) galaxies. We are using these results, together with the public data, for further analysis of the variations of properties in relation to redshift within $z<1.0$.
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