Cluster Galaxy Morphologies: The Relationship among Structural Parameters, Activity and the Environment

We use an approach to estimate galaxy morphologies based on an ellipticity (e) vs. Bulge-to-Total ratio (B/T) plane. We have calibrated this plane by comparing with Dressler's classifications. With the aid of our calibration, we have classified 635 galaxies in 18 Abell clusters (0.02 < z < 0.08). Our approach allowed us to recover the Kormendy's relation. We found that ellipticals and Spirals are slightly brighter than S0 in R band. As S0 bulges are brighter than spirals bulges, we believe that ram pressure is not the main mechanism to generate S0s. In our sample, cluster radio galaxies morphologies cover the range S0-E-cD and their bulges have absolutes magnitudes distributed within -21 mag < M < -24.5 mag. If we believe Ferrarese & Merrit's relation, these radio sources have 10^8-10^9 M black hole mass.Comment: Originally published in the proceedings of the conference "The Monster's Fiery Breath: Feedback in Galaxies, Groups, and Clusters", AIP Conference Proceedings, Volume 1201 edited by Sebastian Heinz and Eric Wilcots. This version contains slight modification

Secondary Infall in the Seyfert\u27s Sextet: A Plausible Way out of the Short Crossing Time Paradox

We used integral field spectroscopy from CALIFA DR3 and multiwavelength publicly available data to investigate the star formation histories of galaxies in the Seyfert\u27s Sextet (SS; HCG 79). The galaxies H79a, H79b, H79c, and H79f have low star formation rates despite showing strong signs of interaction. By exploring their individual specific star formation histories, we identified three earlier episodes of strong star formation common to these four galaxies. We use the last two episodes as markers of the epochs when the galaxies were crossing. We suggest that after the first turnaround, initially gas-rich galaxies crossed for the first time, consuming most of their gas. Hence, after the second turnaround most mergers from second crossings would be mixed or dry. The exception would be gas-rich galaxies intruding for the first time. Therefore, we suggest that SS galaxies have survived one crossing during a Hubble time. Strong Balmer absorption lines and the presence of counter-rotating disks provide independent bounds to the second and first crossing, respectively. This scenario provides a plausible way out of the short crossing time paradox

Secondary Infall in the Seyfert's Sextet:A Plausible Way Out of the Short Crossing Time Paradox

We used integral field spectroscopy from CALIFA DR3 and multiwavelength publicly-available data to investigate the star-formation histories of galaxies in the Seyfert's Sextet (SS, HCG 79). The galaxies H79a, H79b, H79c, and H79f have low star-formation rates despite showing strong signs of interaction. By exploring their individual specific star formation histories (sSFH), we identified three earlier episodes of strong star formation common to these four galaxies. We use the last two episodes as markers of the epochs when the galaxies were crossing. We suggest that after the first turn-around, initially gas-rich galaxies crossed for the first time, consuming most of their gas. Hence after the second turn-around most mergers from second crossings would be mixed or dry. The exception would be gas-rich galaxies intruding for the first time. Therefore, we suggest that SS galaxies have survived one crossing during a Hubble time. Strong Balmer absorption lines and the presence of counter-rotating disks provide independent bounds to the second and first crossing, respectively. This scenario provides a plausible way out of the short crossing time paradox.Comment: 21 pages, 5 figues, accepted for publication in ApJ Letter

2D surface brightness modelling of large 2MASS galaxies – I : Photometry and structural parameters

We have studied a sample of 101 bright 2MASS galaxies from the Large Galaxy Atlas (LGA), whose morphologies span from early to late types. We have generated estimates for structural parameters through a two-dimensional surface brightness photometric decomposition in the three 2MASS bands (J, H, and Ks). This work represents a detailed multicomponent photometric study of nearby galaxies. We report total magnitudes, effective radii, and concentration indices, among other parameters, in the three 2MASS bands. We found that the integrated total magnitudes of early-type galaxies (ETGs) measured on 2MASS LGA mosaics are ∼0.35 mag dimmer, when compared with images generated from IRSA image tile service; nevertheless, when comparing late-type galaxies (LTGs) we did not find any difference. Therefore, for ETGs we present the results derived on IRSA image tiles, while for LTGs we used data from the LGA mosaics. Additionally, by combining these structural parameters with scaling relations and kinematic data, we separated classical bulges from pseudo-bulges. We found that ∼40 per cent of the objects in our sample are classified as pseudo-bulges, which are found preferentially in LTGs. Also, our findings confirm trends reported earlier in the distributions for some physical parameters, such as Sérsic index and B/T and q ratios. In general, our results are in agreement with previous one-dimensional studies. In a companion paper, we revise some of the scaling relations among global galaxy properties, as well as their interrelation with Supermassive Black Holes