Quintessential Affleck-Dine baryogenesis with non-minimal couplings

We present a novel Affleck-Dine scenario for the generation of the observed baryon asymmetry of the Universe based on the non-trivial interplay between quintessential inflationary models containing a kinetic dominated post-inflationary era and a non-minimally coupled $U(1)$ field with a weakly broken $B-L$ symmetry. The non-minimal coupling to gravity renders heavy the Affleck-Dine field during inflation and avoids the generation of isocurvature fluctuations. During the subsequent kinetic era the Ricci scalar changes sign and the effective mass term of the Affleck-Dine field becomes tachyonic. This allows the field to dynamically acquire a large expectation value. The symmetry of the Affleck-Dine potential is automatically restored at the onset of radiation domination, when the Ricci scalar approximately equals zero. This inverse phase transition results in the coherent oscillation of the scalar field around the origin of its effective potential. The rotation of the displaced Affleck-Dine field in the complex plane generates a non-zero $B-L$ asymmetry which can be eventually converted into a baryon asymmetry via the usual transfer mechanisms.Comment: 9 pages, 1 figure, minor corrections and clarifications added. Matches the published versio

The visible environment of galaxies with counterrotation

In this paper we present a statistical study of the environments of 49 galaxies in which there is gas- or stellar- counterrotation. The number of possible companions in the field (to apparent magnitude 22), their size and concentration were considered. All the statistical parameters were analysed by means of Kolgomorov-Smirnov tests, using a control sample of 43 galaxies without counterrotation. From our data, no significant differences between the counter-rotating and control samples appear. This is different to Seyfert or radio-loud galaxies which lie in environments with a higher density of companions. On the contrary, if a weak tendency exists, for galaxies with gas counterrotation only, it is discovered in regions of space where the large scale density of galaxies is smaller. Our results tend to disprove the hypothesis that counterrotation and polar rings derive from a recent interaction with a small satellite or a galaxy of similar size. To a first approximation, they seem to follow the idea that all galaxies are born through a merger process of smaller objects occurring very early in their life, or that they derive from a continuous, non-traumatic infall of gas that formed stars later. Whatever the special machinery is which produces counterrotation or polar rings instead of a co-planar, co-rotating distribution of gas and stars, it seems not to be connected to the present galaxy density of their environments.Comment: 9 pages, 1 figure, accepted for publication in A&

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

Testing Lorentz invariance of dark matter with satellite galaxies

We develop the framework for testing Lorentz invariance in the dark matter sector using galactic dynamics. We consider a Lorentz violating (LV) vector field acting on the dark matter component of a satellite galaxy orbiting in a host halo. We introduce a numerical model for the dynamics of satellites in a galactic halo and for a galaxy in a rich cluster to explore observational consequences of such an LV field. The orbital motion of a satellite excites a time dependent LV force which greatly affects its internal dynamics. Our analysis points out key observational signatures which serve as probes of LV forces. These include modifications to the line of sight velocity dispersion, mass profiles and shapes of satellites. With future data and a more detailed modeling these signatures can be exploited to constrain a new region of the parameter space describing the LV in the dark matter sector.Comment: 27 pages, 11 figures, 2 tables, 1 appendix. Minor corrections in section 4.3.

Molecular gas and star formation in M81

We present IRAM 30m observations of the central 1.6 kpc of the spiral M81 galaxy. The molecular gas appears weak and with an unusual excitation physics. We discuss a possible link between low CO emission and weak FUV surface brightness.Comment: 2 pages, 2 figures, to appear in "Pathways through an eclectic Universe", J. H. Knapen, T. J. Mahoney, and A. Vazdekis (Eds.), ASP Conf. Ser., 200

Hidden interaction in SBO galaxies

Galaxies, like plants, show a large variety of grafts: an individual of some type connects physically with a neighborhood of same or different type. The effects of these interactions between galaxies have a broad range of morphologies depending, among other quantities, on the distance of the closest approach between systems and the relative size of the two galaxies. A sketch of the possible situations is shown in tabular form. This botanical classification is just indicative, because the effects of interactions can be notable also at relatively large separations, when additional conditions are met, as for example low density of the interacting systems or the presence of intra-cluster gas. In spite of the large variety of encounters and effects, in the literature the same terms are often used to refer to different types of interactions. Analysis indicates that only few of the situations show evident signs of interaction. They appear to be most relevant when the size of the two galaxies is comparable. Bridges and tails, like the well known case of NGC 4038/39, the Antennae, are only observed for a very low percentage of all galaxies (approx. 0.38 percent, Arp and Madore 1977). In most cases of gravitational bond between two galaxies, the effects of interactions are not relevant or evident. For instance, the detection of stellar shells (Malin and Carter 1983), which have been attributed to the accretion of gas stripped from another galaxy or to the capture and disruption of a small stellar system (Quinn 1984), requires particular observing and reduction techniques. Besides these difficulties of detection, time plays an important role in erasing, within a massive galaxy, the effects of interactions with smaller objects. This can happen on a timescale shorter than the Hubble time, so the number of systems now showing signs of interaction suggests lower limits to the true frequency of interactions in the life-time of a stellar system

Low redshift quasars in the SDSS Stripe 82. The local environments

We study the environments of low redshift (z < 0.5) quasars based on a large and homogeneous dataset from the Stripe 82 region of the Sloan Digital Sky Survey (SDSS). We have compared the < 1 Mpc scale envi- ronments of 302 quasars that were resolved in our recent study to those of 288 inactive galaxies with closely matched redshifts. Crucially, the lu- minosities of the inactive galaxies and the quasar host galaxies are also closely matched, unlike in most previous studies. The environmental overdensities were studied by measuring the num- ber density of galaxies within a projected distance of 200 kpc to 1 Mpc. The galaxy number density of the quasar environments is comparable to that of the inactive galaxies with similar luminosities, both classes of ob- jects showing significant excess compared to the background galaxy density for distances < 400 kpc. There is no significant dependence of the galaxy number density on redshift, quasar or host galaxy luminosity, black hole mass or radio loudness. This suggests that the fueling and triggering of the nuclear activity is only weakly dependent on the local environment of quasars, and the quasar phase may be a short-lived common phase in the life cycle of all massive galaxies.Comment: Accepted for publication in MNRAS, 16 page