1,729 research outputs found
The GeV to TeV view of SNR IC443: predictions for Fermi
We present a theoretical model that explains the high energy phenomenology of
the neighborhood of SNR IC 443, as observed with the Major Atmospheric Gamma
Imaging Cherenkov (MAGIC) telescope and the Energetic Gamma-Ray Experiment
Telescope (EGRET). We also discuss how the model can be tested with
observations by the Fermi Gamma-ray Large Area Space Telescope. We interpret
MAGIC J0616+225 as delayed TeV emission of cosmic-rays diffusing from IC 443
and interacting with a known cloud located at a distance of about 20 pc in the
foreground of the remnant. This scenario naturally explains the displacement
between EGRET and MAGIC sources, their fluxes, and their spectra. Finally, we
predict how this context can be observed by Fermi.Comment: To appear in the Proceedings of the 6th Workshop on Science with the
New Generation of High Energy Gamma-Ray Experiments (SciNeGHE '08), held in
Padova October 200
Broad-band nonthermal emission from molecular clouds illuminated by cosmic rays from nearby supernova remnants
Molecular clouds are expected to emit non-thermal radiation due to cosmic ray
interactions in the dense magnetized gas. Such emission is amplified if a cloud
is located close to an accelerator of cosmic rays and if energetic particles
can leave the accelerator site and diffusively reach the cloud. We consider
here the situation in which a molecular cloud is located in the proximity of a
supernova remnant which is efficiently accelerating cosmic rays and gradually
releasing them in the interstellar medium. We calculate the multiwavelength
spectrum from radio to gamma rays which is emerging from the cloud as the
result of cosmic ray interactions. The total energy output is dominated by the
gamma ray emission, which can exceed the emission in other bands by an order of
magnitude or more. This suggests that some of the unidentified TeV sources
detected so far, with no obvious or very weak counterparts in other
wavelengths, might be in fact associated with clouds illuminated by cosmic rays
coming from a nearby source. Moreover, under certain conditions, the gamma ray
spectrum exhibit a concave shape, being steep at low energies and hard at high
energies. This fact might have important implications for the studies of the
spectral compatibility of GeV and TeV gamma ray sources.Comment: 13 pages, 6 figures, submitted to MNRA
MAGIC J0616+225 as delayed TeV emission of cosmic-rays diffusing from SNR IC 443
We present a theoretical model that explains the high energy phenomenology of
the neighborhood of SNR IC 443, as observed with the Major Atmospheric Gamma
Imaging Cherenkov (MAGIC) telescope and the Energetic Gamma-Ray Experiment
Telescope (EGRET). We interpret MAGIC J0616+225 as delayed TeV emission of
cosmic-rays diffusing from IC 443 and interacting with a known cloud located at
a distance of about 20 pc in the foreground of the remnant. This scenario
naturally explains the displacement between EGRET and MAGIC sources, their
fluxes, and their spectra. We compare this model with others recently
presented, and discuss how it can be tested with observations by the Gamma-ray
Large Area Telescope (GLAST).Comment: Accepted for publication in MNRAS Letter
Multi-messenger model for the starburst galaxy M82
In this paper, a consistent model of the multifrequency emission of the
starburst galaxy M82, from radio to gamma-rays is presented and discussed.
Predictions for observations with Fermi, MAGIC II/VERITAS and CTA telescopes
are made. The model is also used to self-consistenty compute the (all flavors)
emission of neutrinos resulting from this starburst galaxy, what can be used in
considerations of the diffuse contributions of such objects.Comment: Accepted for publication in The Astrophysical Journa
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Arecibon planetaarisen tutkan Maan lähiasteroidihavainnot: 2017 joulukuu - 2019 joulukuu
We successfully observed 191 near-Earth asteroids using the Arecibo Observatory's S-band planetary radar system from 2017 December through 2019 December. We present radar cross sections for 167 asteroids; circular-polarization ratios for 112 asteroids based on Doppler-echo-power spectra measurements; and radar albedos, constraints on size and spin periods, and surface-feature and shape evaluation for 37 selected asteroids using delay-Doppler radar images with a range resolution of 75 m or finer. Out of 33 asteroids with an estimated effective diameter of at least 200 m and sufficient image quality to give clues of the shape, at least 4 (∼12%) are binary asteroids, including 1 equal-mass binary asteroid, 2017 YE5, and at least 10 (∼30%) are contact-binary asteroids. For 5 out of 112 asteroids with reliable measurements in both circular polarizations, we measured circular-polarization ratios greater than 1.0, which could indicate that they are E-type asteroids, while the mean and the 1σ standard deviation were 0.37 ± 0.23. Further, we find a mean opposite-sense circular-polarization radar albedo of 0.21 ± 0.11 for 41 asteroids (0.19 ± 0.06 for 11 S-complex asteroids). We identified two asteroids, 2011 WN15 and (505657) 2014 SR339, as possible metal-rich objects based on their unusually high radar albedos, and discuss possible evidence of water ice in 2017 YE5.Peer reviewe
Computational approaches to explainable artificial intelligence: Advances in theory, applications and trends
Deep Learning (DL), a groundbreaking branch of Machine Learning (ML), has emerged as a driving force in both theoretical and applied Artificial Intelligence (AI). DL algorithms, rooted in complex and non-linear artificial neural systems, excel at extracting high-level features from data. DL has demonstrated human-level performance in real-world tasks, including clinical diagnostics, and has unlocked solutions to previously intractable problems in virtual agent design, robotics, genomics, neuroimaging, computer vision, and industrial automation. In this paper, the most relevant advances from the last few years in Artificial Intelligence (AI) and several applications to neuroscience, neuroimaging, computer vision, and robotics are presented, reviewed and discussed. In this way, we summarize the state-of-the-art in AI methods, models and applications within a collection of works presented at the 9th International Conference on the Interplay between Natural and Artificial Computation (IWINAC). The works presented in this paper are excellent examples of new scientific discoveries made in laboratories that have successfully transitioned to real-life applications.MCIU - Nvidia(UMA18-FEDERJA-084
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV
A search for new physics is presented based on an event signature of at least
three jets accompanied by large missing transverse momentum, using a data
sample corresponding to an integrated luminosity of 36 inverse picobarns
collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector
at the LHC. No excess of events is observed above the expected standard model
backgrounds, which are all estimated from the data. Exclusion limits are
presented for the constrained minimal supersymmetric extension of the standard
model. Cross section limits are also presented using simplified models with new
particles decaying to an undetected particle and one or two jets
Combined search for the quarks of a sequential fourth generation
Results are presented from a search for a fourth generation of quarks
produced singly or in pairs in a data set corresponding to an integrated
luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in
2011. A novel strategy has been developed for a combined search for quarks of
the up and down type in decay channels with at least one isolated muon or
electron. Limits on the mass of the fourth-generation quarks and the relevant
Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a
simple extension of the standard model with a sequential fourth generation of
fermions. The existence of mass-degenerate fourth-generation quarks with masses
below 685 GeV is excluded at 95% confidence level for minimal off-diagonal
mixing between the third- and the fourth-generation quarks. With a mass
difference of 25 GeV between the quark masses, the obtained limit on the masses
of the fourth-generation quarks shifts by about +/- 20 GeV. These results
significantly reduce the allowed parameter space for a fourth generation of
fermions.Comment: Replaced with published version. Added journal reference and DO
Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV
The t t-bar production cross section (sigma[t t-bar]) is measured in
proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS
experiment, corresponding to an integrated luminosity of 2.3 inverse
femtobarns. The measurement is performed in events with two leptons (electrons
or muons) in the final state, at least two jets identified as jets originating
from b quarks, and the presence of an imbalance in transverse momentum. The
measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/-
2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction
of the standard model.Comment: Replaced with published version. Included journal reference and DO
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