Potential of a neutrino detector in the ANDES underground laboratory for geophysics and astrophysics of neutrinos

The construction of the Agua Negra tunnels that will link Argentina and Chile under the Andes, the world's longest mountain range, opens the possibility of building the first deep underground laboratory in the Southern Hemisphere. This laboratory has the acronym ANDES (Agua Negra Deep Experiment Site) and its overburden could be as large as similar to 1.7 km of rock, or 4500 mwe, providing an excellent low background environment to study physics of rare events like the ones induced by neutrinos and/or dark matter. In this paper we investigate the physics potential of a few kiloton size liquid scintillator detector, which could be constructed in the ANDES laboratory as one of its possible scientific programs. In particular, we evaluate the impact of such a detector for the studies of geoneutrinos and Galactic supernova neutrinos, assuming a fiducial volume of 3 kilotons as a reference size. We emphasize the complementary roles of such a detector to the ones of the Northern Hemisphere neutrino facilities, given the advantages of its geographical location.

CENTAURUS A: THE EXTRAGALACTIC SOURCE OF COSMIC RAYS WITH ENERGIES ABOVE THE KNEE

The origin of cosmic rays at all energies is still uncertain. In this paper, we present and explore an astrophysical scenario to produce cosmic rays with energy ranging from below 10(15) to 3 x 10(20) eV. We show here that just our Galaxy and the radio galaxy Cen A, each with their own galactic cosmic-ray particles but with those from the radio galaxy pushed up in energy by a relativistic shock in the jet emanating from the active black hole, are sufficient to describe the most recent data in the PeV to near ZeV energy range. Data are available over this entire energy range from the KASCADE, KASCADE-Grande, and Pierre Auger Observatory experiments. The energy spectrum calculated here correctly reproduces the measured spectrum beyond the knee and, contrary to widely held expectations, no other extragalactic source population is required to explain the data even at energies far below the general cutoff expected at 6 x 10(19) eV, the Greisen-Zatsepin-Kuz'min turnoff due to interaction with the cosmological microwave background. We present several predictions for the source population, the cosmic-ray composition, and the propagation to Earth which can be tested in the near future.

Evolution of a dense neutrino gas in matter and electromagnetic field

We describe the system of massive Weyl fields propagating in a background matter and interacting with an external electromagnetic field. The interaction with an electromagnetic field is due to the presence of anomalous magnetic moments. To canonically quantize this system first we develop the classical field theory treatment of Weyl spinors in frames of the Hamilton formalism which accounts for the external fields. Then, on the basis of the exact solution of the wave equation for a massive Weyl field in a background matter we obtain the effective Hamiltonian for the description of spin-flavor oscillations of Majorana neutrinos in matter and a magnetic field. Finally, we incorporate in our analysis the neutrino self-interaction which is essential when the neutrino density is sufficiently high. We also discuss the applicability of our results for the studies of collective effects in spin-flavor oscillations of supernova neutrinos in a dense matter and a strong magnetic field. (C) 2011 Elsevier B.V. All rights reserved.

VVV DR1: The first data release of the Milky Way bulge and southern plane from the near-infrared ESO public survey VISTA variables in the Via Lactea

Context. The ESO public survey VISTA variables in the Via Lactea (VVV) started in 2010. VVV targets 562 sq. deg in the Galactic bulge and an adjacent plane region and is expected to run for about five years. Aims. We describe the progress of the survey observations in the first observing season, the observing strategy, and quality of the data obtained. Methods. The observations are carried out on the 4-m VISTA telescope in the ZYJHK(s) filters. In addition to the multi-band imaging the variability monitoring campaign in the K-s filter has started. Data reduction is carried out using the pipeline at the Cambridge Astronomical Survey Unit. The photometric and astrometric calibration is performed via the numerous 2MASS sources observed in each pointing. Results. The first data release contains the aperture photometry and astrometric catalogues for 348 individual pointings in the ZYJHK(s) filters taken in the 2010 observing season. The typical image quality is similar to 0 ''.9-1 ''.0. The stringent photometric and image quality requirements of the survey are satisfied in 100% of the JHK(s) images in the disk area and 90% of the JHK(s) images in the bulge area. The completeness in the Z and Y images is 84% in the disk, and 40% in the bulge. The first season catalogues contain 1.28 x 10(8) stellar sources in the bulge and 1.68 x 10(8) in the disk area detected in at least one of the photometric bands. The combined, multi-band catalogues contain more than 1.63 x 10(8) stellar sources. About 10% of these are double detections because of overlapping adjacent pointings. These overlapping multiple detections are used to characterise the quality of the data. The images in the JHK(s) bands extend typically similar to 4 mag deeper than 2MASS. The magnitude limit and photometric quality depend strongly on crowding in the inner Galactic regions. The astrometry for K-s = 15-18 mag has rms similar to 35-175 mas. Conclusions. The VVV Survey data products offer a unique dataset to map the stellar populations in the Galactic bulge and the adjacent plane and provide an exciting new tool for the study of the structure, content, and star-formation history of our Galaxy, as well as for investigations of the newly discovered star clusters, star-forming regions in the disk, high proper motion stars, asteroids, planetary nebulae, and other interesting objects.

The spectrum of high-energy cosmic rays measured with KASCADE-Grande

The energy spectrum of cosmic rays between 10(16) eV and 10(18) eV, derived from measurements of the shower size (total number of charged particles) and the total muon number of extensive air showers by the KASCADE-Grande experiment, is described. The resulting all-particle energy spectrum exhibits strong hints for a hardening of the spectrum at approximately 2 . 10(16) eV and a significant steepening at approximate to 8 . 10(16) eV. These observations challenge the view that the spectrum is a single power law between knee and ankle. Possible scenarios generating such features are discussed in terms of astrophysical processes that may explain the transition region from galactic to extragalactic origin of cosmic rays. (C) 2012 Elsevier B.V. All rights reserved.

Effects of high-energy astrophysical events on habitable planets

With the possible exception of meteor impacts, high-energy astrophysical events such as supernovae, gamma-ray bursts (GRB) and flares are usually not taken into account for biological and evolutionary studies due to their low rates of occurrence. We show that a class of these events may occur at distances and time scales in which their biological effects are non-negligible, maybe more frequent than the impacts of large asteroids. We review the effects of four transient astrophysical sources of ionizing radiation on biospheres - stellar flares, giant flares from soft gamma repeaters (SGR), supernovae and GRB. The main damaging features of them are briefly discussed and illustrated. We point out some open problems and ongoing work. Received 28 February 2012, accepted 6 July 2012, first published online 10 August 2012

The peculiar isolated neutron star in the Carina Nebula Deep XMM-Newton and ESO-VLT observations of 2XMM J104608.7-594306

While fewer in number than the dominant rotation-powered radio pulsar population, peculiar classes of isolated neutron stars (INSs) which include magnetars, the ROSAT-discovered "Magnificent Seven" (M7), rotating radio transients (RRATs), and central compact objects in supernova remnants (CCOs) - represent a key element in understanding the neutron star phenomenology. We report the results of an observational campaign to study the properties of the source 2XMM J104608.7-594306, a newly discovered thermally emitting INS. The evolutionary state of the neutron star is investigated by means of deep dedicated observations obtained with the XMM-Newton Observatory, the ESO Very Large Telescope, as well as publicly available gamma-ray data from the Fermi Space Telescope and the AGILE Mission. The observations confirm previous expectations and reveal a unique type of object. The source, which is likely within the Carina Nebula (N-H = 2.6x10(21) cm(-2)), has a spectrum that is both thermal and soft, with kT(infinity) = 135 eV. Non-thermal (magnetospheric) emission is not detected down to 1% (3 sigma, 0.1-12 keV) of the source luminosity. Significant deviations (absorption features) from a simple blackbody model are identified in the spectrum of the source around energies 0.6 keV and 1.35 keV. While the former deviation is likely related to a local oxygen overabundance in the Carina Nebula, the latter can only be accounted for by an additional spectral component, which is modelled as a Gaussian line in absorption with EW = 91 eV and sigma = 0.14 keV (1 sigma). Furthermore, the optical counterpart is fainter than m(V) = 27 (2 sigma) and no gamma-ray emission is significantly detected by either the Fermi or AGILE missions. Very interestingly, while these characteristics are remarkably similar to those of the M7 or the only RRAT so far detected in X-rays, which all have spin periods of a few seconds, we found intriguing evidence of very rapid rotation, P = 18.6ms, at the 4 sigma confidence level. We interpret these new results in the light of the observed properties of the currently known neutron star population, in particular those of standard rotation-powered pulsars, recycled objects, and CCOs. We find that none of these scenarios can satisfactorily explain the collective properties of 2XMM J104608.7-594306, although it may be related to the still poorly known class of Galactic anti-magnetars. Future XMM-Newton data, granted for the next cycle of observations (AO11), will help us to improve our current observational interpretation of the source, enabling us to significantly constrain the rate of pulsar spin down.

Mass extinctions, galactic orbits in the solar neighborhood and the Sun: a connection?

The orbits of the stars in the disk of the Galaxy, and their passages through the Galactic spiral arms, are a rarely mentioned factor of biosphere stability which might be important for long-term planetary climate evolution, with a possible bearing on mass extinctions. The Sun lies very near the co-rotation radius, where stars revolve around the Galaxy in the same period as the density wave perturbations of the spiral arms. conventional wisdom generally considers that this status makes for few passages through the spiral arms. Controversy still surrounds whether time spent inside or around spiral arms is dangerous to biospheres and conductive to mass extinctions. Possible threats include giant molecular clouds disturbing the Oort comet cloud and provoking heavy bombardment: a higher exposure to cosmic rays near star forming regions triggering increased cloudiness in Earth atmosphere and ice ages; and the desctruction of Earth's ozone layer posed by supernova explosiosn. We present detailed calculations of the history of spiral arm passages for all 212 solar-type stars nearer than 20 parsecs, including the total time spent inside armsin the last 500 Myr, when the spiral arm position can be traced with good accuracy. We found that there is a large diversity of stellar orbits in the solar neighborhood, and the time fraction spent inside spiral arms can vary from a few percent to nearly half the time. The Sun, despite its proximity to the galactic co-rotation radius, has exceptionally low eccentricity and a low vertical velocity component, and therefore spends 30% of its lifetime crossing the spiral arms, more than most nearby stars. We discuss the possible implications of this fact to the long-term habitability of the Earth, and possible correlations of the Sun's passage through the spiral arms with the five great mass extinctions of the Earth's biosphere from the Late Ordovician to the Cretaceous-Tertiary.