The visible environment of polar ring galaxies

A statistical study of the environment around Polar Ring Galaxies is presented. Two kinds of search are performed: 1) a study of the concentration and diameters of all the objects surrounding the Polar Rings, within a search field 5 times the ring diameter. New magnitudes for polar ring galaxies are presented. 2) a search, in a wider field, for galaxies of similar size that may have encountered the polar ring host galaxy in a time of the order of 1 Gyr. Differently from the results of similar searches in the fields of active galaxies, the environment of the Polar Ring Galaxies seems to be similar to that of normal galaxies.This result may give support to the models suggesting long times for formation and evolution of the rings. If the rings are old (and stable or in equilibrium), no traces of the past interaction are expected in their surroundings. In addition, the formation of massive polar rings, too big to derive from the ingestion of a present-day dwarf galaxy, may be easily placed in epochs with a higher number of gas-rich galaxies.Comment: Accepted for publication in Astron. Astrophys. Main Journal, 9 pages including 3 postscript figure

On the role of the environments and star formation for quasar activity

We investigate the host galaxy and environment properties of a sample of 400 low z (<0.5) quasars that were imaged in the SDSS Stripe82. We can detect and study the properties of the host galaxy for more than 75% of the data sample. We discover that quasar are mainly hosted in luminous galaxies of absolute magnitude M* -3 < M(R) < M* and that in the quasar environments the galaxy number density is comparable to that of inactive galaxies of similar luminosities. For these quasars we undertake also a study in u,g,r,i and z SDSS bands and again we discover that the mean colours of the quasar host galaxy it is not very different with respect to the values of the sample of inactive galaxies. For a subsample of low z sources the imaging study is complemented by spectroscopy of quasar hosts and of close companion galaxies. This study suggests that the supply and cause of the nuclear activity depends only weakly on the local environment of quasars. Contrary to past suggestions, for low redshift quasar there is a very modest connection between recent star formation and the nuclear activity.Comment: 10 pages, 4 figures, proceedings of the conference "QUASARS at all cosmic epochs", accepted for publication on Frontiers in Astronomy and Space Scienc

The UV window on counter rotating ETGs: insight from SPH simulations with chemo-photometric implementation

The Galaxy Evolution Explorer (GALEX) detected ultraviolet emission in about 50% of multi-spin early-type galaxies (ETGs), suggesting the occurrence of a recent rejuvenation episode connected to the formation of these kinematical features. With the aim at investigating the complex evolutionary scenario leading to the formation of counter rotating ETGs (CR-ETGs) we use our Smooth Particle Hydrodynamic (SPH) code with chemo-photometric implementation. We discuss here the UV evolutionary path of two CR-ETGs, NGC 3593 and NGC 5173, concurrently best fitting their global observed properties, i.e., morphology, dynamics, as well as their total B-band absolute magnitude and spectral energy distribution (SED) extended over three orders of magnitude in wavelength. These simulations correspond to our predictions about the target evolution which we follow in the color-magnitude diagram (CMD), near-UV (NUV) versus r-band absolute magnitude, as a powerful diagnostic tool to emphasize rejuvenation episodes.Comment: 7 pages, 3 figures, accepted for publication in ApS

Evolution of Galaxy morphologies in Clusters

We have studied the evolution of galaxian morphologies from ground-based, good-seeing images of 9 clusters at z=0.09-0.25. The comparison of our data with those relative to higher redshift clusters (Dressler et al. 1997) allowed us to trace for the first time the evolution of the morphological mix at a look-back time of 2-4 Gyr, finding a dependence of the observed evolutionary trends on the cluster properties.Comment: 4 pages with 2 figures in Latex-Kluwer style. To be published in the proceedings of the Granada Euroconference "The Evolution of Galaxies.I-Observational Clues

Comparison on Well-Being, Engagement and Perceived School Climate in Secondary School Students with Learning Difficulties and Specific Learning Disorders: An Exploratory Study

none6noopenLombardi, Elisabetta; Traficante, Daniela; Bettoni, Roberta; Offredi, Ilaria; Vernice, Mirta; Sarti, DanielaLombardi, Elisabetta; Traficante, Daniela; Bettoni, Roberta; Offredi, Ilaria; Vernice, Mirta; Sarti, Daniel

GASP XIX: AGN and their outflows at the center of jellyfish galaxies

The GASP survey, based on MUSE data, is unveiling the properties of the gas in the so-called "jellyfish" galaxies: these are cluster galaxies with spectacular evidence of gas stripping by ram pressure. In a previous paper, we selected the seven GASP galaxies with the most extended tentacles of ionized gas, and based on individual diagnostic diagrams concluded that at least five of them present clear evidence for an Active Galactic Nucleus. Here we present a more detailed analysis of the emission lines properties in these galaxies. Our comparison of several emission line ratios with both AGN and shock models show that photoionization by the AGN is the dominant ionization mechanism. This conclusion is strengthened by the analysis of $\rm H\beta$ luminosities, the presence of nuclear iron coronal lines and extended ($>10$ kpc) emission line regions ionized by the AGN in some of these galaxies. From emission line profiles, we find the presence of outflows in four galaxies, and derive mass outflow rates, timescales and kinetic energy of the outflows.Comment: 20 pages, 10 Figure

Faint Dwarf galaxies in nearby WINGS clusters: photometric characterization

In the cores of galaxy clusters there is a population of lows-mass stellar systems such as dwarf Early-type galaxies, ultra-compact dwarf galaxies (UCDs) and ultra diffuse dwarf galaxies. We present here the photometric and morphological characterization of this population of objects using deep CFHT images of a sample of clusters belonging to the WINGS survey (0.04 < z < 0.06). We study only galaxies that are spectroscopically confirmed members of the cluster. The population of dwarfs ranges from ∽ 30% for the more rich clusters to ∽ 5-6% for the less rich ones

Enhanced star formation in both disks and ram pressure stripped tails of GASP jellyfish galaxies

Exploiting the data from the GAs Stripping Phenomena in galaxies with MUSE (GASP) program, we compare the integrated Star Formation Rate- Mass relation (SFR-M_ast) relation of 42 cluster galaxies undergoing ram pressure stripping ("stripping galaxies") to that of 32 field and cluster undisturbed galaxies. Theoretical predictions have so far led to contradictory conclusions about whether ram pressure can enhance the star formation in the gas disks and tails or not and until now a statistically significant observed sample of stripping galaxies was lacking. We find that stripping galaxies occupy the upper envelope of the control sample SFR-M_ast relation, showing a systematic enhancement of the SFR at any given mass. The star formation enhancement occurs in the disk (0.2 dex), and additional star formation takes place in the tails. Our results suggest that strong ram pressure stripping events can moderately enhance the star formation also in the disk prior to gas removal.Comment: ApJL in pres