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F. Convenga

Publications and source records attributed to F. Convenga.

59 records · Page 4Linked to original sources
arXiv2019

Data-driven estimation of the invisible energy of cosmic ray showers with the Pierre Auger Observatory

The determination of the primary energy of extensive air showers using the fluorescence detection technique requires an estimation of the energy carried away by particles that do not deposit all their energy in the atmosphere. This estimation is typically made using Monte Carlo simulations and thus depends on the assumed primary particle mass and on model predictions for neutrino and muon production. In this work we present a new method to obtain the invisible energy from events detected by the Pierre Auger Observatory. The method uses measurements of the muon number at ground level, and it allows us to reduce significantly the systematic uncertainties related to the mass composition and the high energy hadronic interaction models, and consequently to improve the estimation of the energy scale of the Observatory.

astro-ph.IM↗
arXiv2019

Probing the origin of ultra-high-energy cosmic rays with neutrinos in the EeV energy range using the Pierre Auger Observatory

Neutrinos with energies above $10^{17}$ eV are detectable with the Surface Detector Array of the Pierre Auger Observatory. The identification is efficiently performed for neutrinos of all flavors interacting in the atmosphere at large zenith angles, as well as for Earth-skimming $τ$ neutrinos with nearly tangential trajectories relative to the earth. No neutrino candidates were found in $\sim\,14.7$ years of data taken up to 31 August 2018. This leads to restrictive upper bounds on their flux. The $90\%$ C.L. single-flavor limit to the diffuse flux of ultra-high-energy neutrinos with an $E_ν^{-2}$ spectrum in the energy range $1.0 \times 10^{17}~{\rm eV} - 2.5 \times 10^{19}~{\rm eV}$ is $E^2 {\rm d}N_ν/{\rm d}E_ν< 4.4 \times 10^{-9}~{\rm GeV~cm^{-2}~s^{-1}~sr^{-1}}$, placing strong constraints on several models of neutrino production at EeV energies and on the properties of the sources of ultra-high-energy cosmic rays.

astro-ph.HE↗
arXiv2019

Multi-Messenger Physics with the Pierre Auger Observatory

An overview of the multi-messenger capabilities of the Pierre Auger Observatory is presented. The techniques and performance of searching for Ultra-High Energy neutrinos, photons and neutrons are described. Some of the most relevant results are reviewed, such as stringent upper bounds that were placed to a flux of diffuse cosmogenic neutrinos and photons, bounds placed on neutrinos emitted from compact binary mergers that were detected by LIGO and Virgo during their first and second observing runs, as well as searches for high energy photons and neutrons from the Galactic center that constrain the properties of the putative Galactic PeVatron, observed by the H.E.S.S.\ collaboration. The observation of directional correlations between ultra-high energy cosmic rays and either high energy astrophysical neutrinos or specific source populations, weighted by their electromagnetic radiation, are also discussed. They constitute additional multi-messenger approaches aimed at identifying the sources of high energy cosmic rays.

astro-ph.HE↗
arXiv2017

Optical, near-IR and $X$-ray observations of SN 2015J and its host galaxy

SN 2015J was discovered on April 27th 2015 and is classified as a type IIn supernova. At first, it appeared to be an orphan SN candidate, i.e. without any clear identification of its host galaxy. Here, we present the analysis of the observations carried out {by the VLT 8-m class telescope with the FORS2 camera in the R band and the Magellan telescope (6.5 m) equipped with the IMACS Short-Camera (V and I filters) and the FourStar camera (Ks filter)}. We show that SN 2015J resides in what appears to be a very compact galaxy establishing a relation between the SN event and its natural host. We also present and discuss archival and new $X$-ray data centred on SN 2015J. At the time of the supernova explosion, Swift/XRT observations were made and a weak X-ray source was detected at the location of SN 2015J. Almost one year later, the same source was unambiguously identified during serendipitous observations by Swift/XRT and $XMM$-Newton, clearly showing an enhancement of the 0.3-10 keV band flux by a factor $\simeq 30$ with respect to the initial state. Swift/XRT observations show that the source is still active in the $X$-rays at a level of $\simeq 0.05$ counts s$^{-1}$. The unabsorbed X-ray luminosity derived from the {\it XMM}-Newton slew and SWIFT observations, $L_{x}\simeq 5\times10^{41}$ erg s$^{-1}$, places SN 2015J among the brightest young supernovae in X-rays.

astro-ph.HE↗