Leptogenesis with "Fuzzy Mass Shell" for Majorana Neutrinos

We study the mixing of elementary and composite particles. In quantum field theory the mixing of composite particles originates in the couplings of the constituent quarks and for neutrinos in self-energy diagrams. In the event that the incoming and outgoing neutrinos have different masses, the self-energy diagrams vanish because energy is not conserved but the finite decaying widths make the mixing possible. We can consider the neutrinos to be "fuzzy" states on their mass shell and the mixing is understood as the overlap of two wavefunctions. These considerations restrict the mass difference to be approximately equal to or smaller than the largest of the two widths: abs(M_i - M_j) lessorequal max(Gamma_i, Gamma_j).Comment: 11 pages, 1 figur

Granger Causality and Cross Recurrence Plots in Rheochaos

Our stress relaxation measurements on wormlike micelles using a Rheo-SALS (rheology + small angle light scattering) apparatus allow simultaneous measurements of the stress and the scattered depolarised intensity. The latter is sensitive to orientational ordering of the micelles. To determine the presence of causal influences between the stress and the depolarised intensity time series, we have used the technique of linear and nonlinear Granger causality. We find there exists a feedback mechanism between the two time series and that the orientational order has a stronger causal effect on the stress than vice versa. We have also studied the phase space dynamics of the stress and the depolarised intensity time series using the recently developed technique of cross recurrence plots (CRPs). The presence of diagonal line structures in the CRPs unambiguously proves that the two time series share similar phase space dynamics.Comment: 10 pages, 7 figure

Full-commanding a network: The dictator

A network of chaotic dynamical systems may synchronize. For some networks there is the possibility that, coupling a new node to the network, the synchronization will be commanded by that new node. That possibility depends on the network and on the way the new node is coupled to the network.We consider a coupling that can provide what we call a full-commanding and we define the corresponding full-commandwindow. The limit situations corresponding to a completely connected network and to a completely disconnected one provide us some understanding about what makes a network more receptive or more resistant to commanding

Untangling the X-ray Emission From the Sa Galaxy NGC1291 With Chandra

We present a Chandra ACIS-S observation of the nearby bulge-dominated Sa galaxy NGC1291. The X-ray emission from the bulge resembles the X-ray emission from a sub-class of elliptical and S0 galaxies with low L_X/L_B luminosity ratios. The X-ray emission is composed of a central point-like nucleus, ~50 point sources that are most likely low mass X-ray binaries (LMXBs), and diffuse gas detectable out to a radius of 120" (5.2 kpc). The diffuse gas has a global temperature of 0.32^{+0.04}_{-0.03} keV and metallicity of 0.06 +/- 0.02 solar, and both quantities marginally decrease with increasing radius. The hot gas fills the hole in the HI distribution, and the softening of the spectrum of the X-ray gas with radius might indicate a thermal coupling of the hot and cold phases of the interstellar medium as previously suggested. The integrated X-ray luminosity of the LMXBs, once normalized by the optical luminosity, is a factor of 1.4 less than in the elliptical galaxy NGC4697 or S0 galaxy NGC1553. The difference in L_{X,stellar}/L_B between the galaxies appears to be because of a lack of very bright sources in NGC1291. No sources above 3 x 10^38 ergs/s were found in NGC1291 when ~7 were expected from scaling from NGC4697 and NGC1553. The cumulative L_{X,stellar}/L_B value including only sources below 1.0 x 10^38 ergs/s is remarkably similar between NGC1291 and NGC4697, if a recent surface brightness fluctuation-determined distance is assumed for NGC4697. If this is a common feature of the LMXB population in early-type systems, it might be used as a distance indicator. Finally, a bright, variable (1.6-3.1 x 10^39 ergs/s) source was detected at the optical center of the galaxy. Its spectrum shows excess soft emission superimposed on a highly absorbed power law component, similar to what has been found in several other low luminosity AGN (ABRIDGED).Comment: 13 pages in emulateapj5 style with 11 embedded Postscript figures; minor revisions since last version; accepted by Ap

Deep ROSAT-HRI observations of the NGC 1399/NGC 1404 region: morphology and structure of the X-ray halo

We present the analysis of a deep (167 ks) ROSAT HRI observation of the cD galaxy NGC 1399 in the Fornax cluster. Using both HRI and, at larger radii, archival PSPC data, we find that the radial behavior of the X-ray surface brightness profile is not consistent with a simple Beta model and suggests instead three distinct components. We use a multi-component bidimensional model to study in detail these three components that we identify respectively with the cooling flow region, the galactic and the cluster halo. From these data we derive a binding mass distribution in agreement with that suggested by optical dynamical indicators, with an inner core dominated by luminous matter and an extended dark halo differently distributed on galactic and cluster scales. The HRI data and a preliminary analysis of Chandra public data, allow us to detect significant density fluctuations in the halo. We discuss possible non-equilibrium scenarios to explain the hot halo structure, including tidal interactions with neighboring galaxies, ram stripping from the intra-cluster medium and merging events. In the innermost region of NGC 1399, the comparison between the X-ray and radio emission suggests that the radio emitting plasma is displacing and producing shocks in the hot X-ray emitting gas. We found that the NGC 1404 halo is well represented by a single symmetric Beta model and follows the stellar light profile within the inner 8 kpc. The mass distribution is similar to the `central' component of the NGC 1399 halo. At larger radii ram pressure stripping from the intra-cluster medium produces strong asymmetries in the gas distribution. Finally we discuss the properties of the point source population finding evidence of correlation between the source excess and NGC 1399.Comment: 34 pages in aastex5.0 format, including 28 B&W and 4 color figures. Uses LaTex packages: subfigure, lscape and psfig. Accepted for publication in ApJ. High resolution version can be found at: http://www.na.astro.it/~paolillo/publications.htm

The Ionized Gas Kinematics of the LMC-Type Galaxy NGC 1427A in the Fornax Cluster

NGC 1427A is a LMC-like irregular galaxy in the Fornax cluster with an extended pattern of strong star formation around one of its edges, which is probably due to some kind of interaction with the cluster environment. We present H-alpha velocities within NGC 1427A, obtained through long-slit spectroscopy at seven different positions, chosen to fall on the brightest HII regions of the galaxy. Due to its location very near the center of the cluster this object is an excellent candidate to study the effects that the cluster environment has on gas-rich galaxies embedded in it. The rotation of NGC 1427A is modeled in two different ways. The global ionized gas kinematics is reasonably well described by solid-body rotation, although on small scales it shows a chaotic behaviour. In this simple model, the collision with a smaller member of the cluster as being responsible for the peculiar morphology of NGC 1427A is very unlikely, since the only candidate intruder falls smoothly into the general velocity pattern of the main galaxy. In a more elaborate model, for which we obtain a better solution, this object does not lie in the same plane of NGC 1427A, in which case we identify it as a satellite bound to the galaxy. These results are discussed in the context of a normal irregular versus one interacting with some external agent. Based on several arguments and quantitative estimates, we argue that the passage through the hot intracluster gas of the Fornax cluster is a very likely scenario to explain the morphological properties of NGC 1427A.Comment: 31 pages, LaTeX2e, uses aas2pp4.sty and psfig.sty, including 7 Postscript figures; accepted for publication in ApJ, Vol. 530, February 200

Inflationary Baryogenesis

In this letter we explore the possibility of creating the baryon asymmetry of the universe during inflation and reheating due to the decay of a field associated with the inflaton. CP violation is attained by assuming that this field is complex with a phase that varies as the inflaton evolves. We consider chaotic and natural inflation scenarios. In the former case, the complex decaying field is the inflaton itself and, in the latter case, the phase of the complex field is the inflaton. We calculate the asymmetry produced using the Bogolyubov formalism that relates annihilation and creation operators at late time to the annihilation and creation operators at early time.Comment: 17 pages, Revte

Leptogenesis with Heavy Majorana Neutrinos Reexamined

The mass term for Majorana neutrinos explicitly violates lepton number. Several authors have used this fact to create a lepton asymmetry in the universe by considering CP violating effects in the one loop self-energy correction for the decaying heavy Majorana neutrino. We compare and comment on the different approaches used to calculate the lepton asymmetry including those using an effective Hamiltonian and resummed propagators. We also recalculate the asymmetry in the small mass difference limit.Comment: 16 pages, LaTex, 1 figure included. 2 footnotes and 1 reference adde

Galactic-Scale Outflow and Supersonic Ram-Pressure Stripping in the Virgo Cluster Galaxy NGC 4388

The Hawaii Imaging Fabry-Perot Interferometer (HIFI) on the University of Hawaii 2.2m telescope was used to map the Halpha and [O III] 5007 A emission-line profiles across the entire disk of the edge-on Sb galaxy NGC 4388. We confirm a rich complex of highly ionized gas that extends ~4 kpc above the disk of this galaxy. Low-ionization gas associated with star formation is also present in the disk. Evidence for bar streaming is detected in the disk component and is discussed in a companion paper (Veilleux, Bland-Hawthorn, & Cecil 1999; hereafter VBC). Non-rotational blueshifted velocities of 50 - 250 km/s are measured in the extraplanar gas north-east of the nucleus. The brighter features in this complex tend to have more blueshifted velocities. A redshifted cloud is also detected 2 kpc south-west of the nucleus. The velocity field of the extraplanar gas of NGC 4388 appears to be unaffected by the inferred supersonic (Mach number M ~ 3) motion of this galaxy through the ICM of the Virgo cluster. We argue that this is because the galaxy and the high-|z| gas lie behind a Mach cone with opening angle ~ 80 degrees. The shocked ICM that flows near the galaxy has a velocity of ~ 500 km/s and exerts insufficient ram pressure on the extraplanar gas to perturb its kinematics. We consider several explanations of the velocity field of the extraplanar gas. Velocities, especially blueshifted velocities on the N side of the galaxy, are best explained as a bipolar outflow which is tilted by > 12 degrees from the normal to the disk. The observed offset between the extraplanar gas and the radio structure may be due to buoyancy or refractive bending by density gradients in the halo gas. Velocity substructure in the outflowing gas also suggests an interaction with ambient halo gas.Comment: 29 pages including 5 figures, Latex, requires aaspp4.sty, to appear in ApJ, 520 (July 20, 1999 issue

Leptogenesis and Low-energy Observables

We relate leptogenesis in a class of theories to low-energy experimental observables: quark and lepton masses and mixings. With reasonable assumptions motivated by grand unification, one can show that the CP-asymmetry parameter takes a universal form. Furthermore the dilution mass is related to the light neutrino masses. Overall, these models offer a natural explanation for a lepton asymmetry in the early universe.Comment: 10 pages, revised discussion on light neutrino masse