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Author |
Pierre Auger Collaboration (Aab, A. et al); Pastor, S. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
A targeted search for point sources of EeV neutrons |
Type |
Journal Article |
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Year |
2014 |
Publication |
Astrophysical Journal Letters |
Abbreviated Journal |
Astrophys. J. Lett. |
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Volume |
789 |
Issue ![sorted by Issue field, descending order (down)](img/sort_desc.gif) |
2 |
Pages |
L34 - 7pp |
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Keywords |
cosmic rays; Galaxy: disk; methods: data analysis |
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Abstract |
A flux of neutrons from an astrophysical source in the Galaxy can be detected in the Pierre Auger Observatory as an excess of cosmic-ray air showers arriving from the direction of the source. To avoid the statistical penalty for making many trials, classes of objects are tested in combinations as nine “target sets,” in addition to the search for a neutron flux from the Galactic center or from the Galactic plane. Within a target set, each candidate source is weighted in proportion to its electromagnetic flux, its exposure to the Auger Observatory, and its flux attenuation factor due to neutron decay. These searches do not find evidence for a neutron flux from any class of candidate sources. Tabulated results give the combined p-value for each class, with and without the weights, and also the flux upper limit for the most significant candidate source within each class. These limits on fluxes of neutrons significantly constrain models of EeV proton emission from non-transient discrete sources in the Galaxy. |
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Address |
[Aab, A.; Buchholz, P.; Erfani, M.; Frohlich, U.; Heimann, P.; Homola, P.; Niechciol, M.; Ochilo, L.; Risse, M.; Yushkov, A.; Ziolkowski, M.] Univ Siegen, D-57068 Siegen, Germany |
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Publisher |
Iop Publishing Ltd |
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English |
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ISSN |
2041-8205 |
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Notes |
WOS:000339876800009 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1885 |
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Permanent link to this record |
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Author |
ANTARES Collaboration (Bhandari, S. et al); Barrios-Marti, J.; Coleiro, A.; Hernandez-Rey, J.J.; Illuminati, G.; Tönnis, C.; Zornoza, J.D.; Zuñiga, J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
The SUrvey for Pulsars and Extragalactic Radio Bursts – II. New FRB discoveries and their follow-up |
Type |
Journal Article |
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Year |
2018 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Mon. Not. Roy. Astron. Soc. |
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Volume |
475 |
Issue ![sorted by Issue field, descending order (down)](img/sort_desc.gif) |
2 |
Pages |
1427-1446 |
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Keywords |
radiation mechanisms: general; methods: data analysis; methods: observational; surveys; intergalactic medium; radio continuum: general |
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Abstract |
We report the discovery of four Fast Radio Bursts (FRBs) in the ongoing SUrvey for Pulsars and Extragalactic Radio Bursts at the Parkes Radio Telescope: FRBs 150610, 151206, 151230 and 160102. Our real-time discoveries have enabled us to conduct extensive, rapid multimessenger follow-up at 12 major facilities sensitive to radio, optical, X-ray, gamma-ray photons and neutrinos on time-scales ranging from an hour to a few months post-burst. No counterparts to the FRBs were found and we provide upper limits on afterglow luminosities. None of the FRBs were seen to repeat. Formal fits to all FRBs show hints of scattering while their intrinsic widths are unresolved in time. FRB 151206 is at low Galactic latitude, FRB 151230 shows a sharp spectral cut-off, and FRB 160102 has the highest dispersion measure (DM = 2596.1 +/- 0.3 pc cm(-3)) detected to date. Three of the FRBs have high dispersion measures (DM > 1500 pc cm(-3)), favouring a scenario where the DMis dominated by contributions from the intergalactic medium. The slope of the Parkes FRB source counts distribution with fluences > 2 Jy ms is alpha = – 2.2(-1.2)(+0.6) and still consistent with a Euclidean distribution (alpha = -3/2). We also find that the all-sky rate is 1.7(-0.9)(+1.5) x 10(3)FRBs/(4 pi sr)/day above similar to 2 Jy ms and there is currently no strong evidence for a latitude- dependent FRB sky rate. |
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Address |
[Bhandari, S.; Keane, E. F.; Barr, E. D.; Jameson, A.; Petroff, E.; Bailes, M.; Flynn, C.; Jankowski, F.; Krishnan, V. Venkatraman; Morello, V.; van Straten, W.; Andreoni, I.; Cooke, J.; Pritchard, T.] Swinburne Univ Technol, Ctr Astrophys & Supercomp, Mail H30,POB 218, Hawthorn, Vic 3122, Australia, Email: shivanibhandari58@gmail.com |
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Publisher |
Oxford Univ Press |
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English |
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ISSN |
0035-8711 |
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Conference |
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Notes |
WOS:000427345900001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3518 |
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Permanent link to this record |
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Author |
ANTARES Collaboration (Albert, A. et al); Barrios-Marti, J.; Coleiro, A.; Colomer, M.; Hernandez-Rey, J.J.; Illuminati, G.; Lotze, M.; Zornoza, J.D.; Zuñiga, J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
The search for high-energy neutrinos coincident with fast radio bursts with the ANTARES neutrino telescope |
Type |
Journal Article |
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Year |
2019 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Mon. Not. Roy. Astron. Soc. |
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Volume |
482 |
Issue ![sorted by Issue field, descending order (down)](img/sort_desc.gif) |
1 |
Pages |
184-193 |
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Keywords |
acceleration of particles; neutrinos; astroparticle physics; radio continuum: transients; methods: data analysis |
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Abstract |
In the past decade, a new class of bright transient radio sources with millisecond duration has been discovered. The origin of these so-called fast radio bursts (FRBs) is still a mystery, despite the growing observational efforts made by various multiwavelength and multimessenger facilities. To date, many models have been proposed to explain FRBs, but neither the progenitors nor the radiative and the particle acceleration processes at work have been clearly identified. In this paper, we assess whether hadronic processes may occur in the vicinity of the FRB source. If they do, FRBs may contribute to the high-energy cosmic-ray and neutrino fluxes. A search for these hadronic signatures was carried out using the ANTARES neutrino telescope. The analysis consists in looking for high-energy neutrinos, in the TeV-PeV regime, that are spatially and temporally coincident with the detected FRBs. Most of the FRBs discovered in the period 2013-2017 were in the field of view of the ANTARES detector, which is sensitive mostly to events originating from the Southern hemisphere. From this period, 12 FRBs were selected and no coincident neutrino candidate was observed. Upper limits on the per-burst neutrino fluence were derived using a power-law spectrum, dN/DE nu proportional to E-nu(-gamma), for the incoming neutrino flux, assuming spectral indexes gamma = 1.0, 2.0, 2.5. Finally, the neutrino energy was constrained by computing the total energy radiated in neutrinos, assuming different distances for the FRBs. Constraints on the neutrino fluence and on the energy released were derived from the associated null results. |
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Address |
[Turpin, D.] Chinese Acad Sci, Natl Astron Observ, Key Lab Space Astron & Technol, Beijing 100101, Peoples R China, Email: dornic@cppm.in2p3.fr; |
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Publisher |
Oxford Univ Press |
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English |
Summary Language |
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ISSN |
0035-8711 |
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Expedition |
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Conference |
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Notes |
WOS:000454575300014 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3860 |
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Permanent link to this record |
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Author |
Gammaldi, V.; Zaldivar, B.; Sanchez-Conde, M.A.; Coronado-Blazquez, J. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
A search for dark matter among Fermi-LAT unidentified sources with systematic features in machine learning |
Type |
Journal Article |
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Year |
2023 |
Publication |
Monthly Notices of the Royal Astronomical Society |
Abbreviated Journal |
Mon. Not. Roy. Astron. Soc. |
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Volume |
520 |
Issue ![sorted by Issue field, descending order (down)](img/sort_desc.gif) |
1 |
Pages |
1348-1361 |
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Keywords |
astroparticle physics – methods; data analysis – methods; observational – methods; statistical – dark matter – gamma-rays; general |
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Abstract |
Around one-third of the point-like sources in the Fermi-LAT catalogues remain as unidentified sources (unIDs) today. Indeed, these unIDs lack a clear, univocal association with a known astrophysical source. If dark matter (DM) is composed of weakly interacting massive particles (WIMPs), there is the exciting possibility that some of these unIDs may actually be DM sources, emitting gamma-rays from WIMPs annihilation. We propose a new approach to solve the standard, machine learning (ML) binary classification problem of disentangling prospective DM sources (simulated data) from astrophysical sources (observed data) among the unIDs of the 4FGL Fermi-LAT catalogue. We artificially build two systematic features for the DM data which are originally inherent to observed data: the detection significance and the uncertainty on the spectral curvature. We do it by sampling from the observed population of unIDs, assuming that the DM distributions would, if any, follow the latter. We consider different ML models: Logistic Regression, Neural Network (NN), Naive Bayes, and Gaussian Process, out of which the best, in terms of classification accuracy, is the NN, achieving around 93 . 3 per cent +/- 0 . 7 per cent performance. Other ML evaluation parameters, such as the True Ne gativ e and True Positive rates, are discussed in our work. Applying the NN to the unIDs sample, we find that the de generac y between some astrophysical and DM sources can be partially solved within this methodology. None the less, we conclude that there are no DM source candidates among the pool of 4FGL Fermi-LAT unIDs. |
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Address |
[Gammaldi, V; Sanchez-Conde, M. A.; Coronado-Blazquez, J.] Univ Autonoma Madrid, Departamentode Fis Teor, E-28049 Madrid, Spain, Email: viviana.gammaldi@uam.es; |
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Thesis |
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Publisher |
Oxford Univ Press |
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English |
Summary Language |
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Series Editor |
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ISSN |
0035-8711 |
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Conference |
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Notes |
WOS:000937053400014 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
5489 |
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Permanent link to this record |
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Author |
Arnalte-Mur, P.; Labatie, A.; Clerc, N.; Martinez, V.J.; Starck, J.L.; Lachieze-Rey, M.; Saar, E.; Paredes, S. |
![goto web page (via DOI) doi](img/doi.gif)
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Title |
Wavelet analysis of baryon acoustic structures in the galaxy distribution |
Type |
Journal Article |
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Year |
2012 |
Publication |
Astronomy & Astrophysics |
Abbreviated Journal |
Astron. Astrophys. |
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Volume |
542 |
Issue ![sorted by Issue field, descending order (down)](img/sort_desc.gif) |
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Pages |
A34 - 11pp |
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Keywords |
large-scale structure of Universe; distance scale; galaxies: cluster: general; methods: data analysis; methods: statistical |
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Abstract |
Context. Baryon acoustic oscillations (BAO) are imprinted in the density field by acoustic waves travelling in the plasma of the early universe. Their fixed scale can be used as a standard ruler to study the geometry of the universe. Aims. The BAO have been previously detected using correlation functions and power spectra of the galaxy distribution. We present a new method to detect the real-space structures associated with BAO. These baryon acoustic structures are spherical shells of relatively small density contrast, surrounding high density central regions. Methods. We design a specific wavelet adapted to search for shells, and exploit the physics of the process by making use of two different mass tracers, introducing a specific statistic to detect the BAO features. We show the effect of the BAO signal in this new statistic when applied to the Lambda – cold dark matter (Lambda CDM) model, using an analytical approximation to the transfer function. We confirm the reliability and stability of our method by using cosmological N-body simulations from the MareNostrum Institut de Ciencies de l'Espai (MICE). Results. We apply our method to the detection of BAO in a galaxy sample drawn from the Sloan Digital Sky Survey (SDSS). We use the “main” catalogue to trace the shells, and the luminous red galaxies (LRG) as tracers of the high density central regions. Using this new method, we detect, with a high significance, that the LRG in our sample are preferentially located close to the centres of shell-like structures in the density field, with characteristics similar to those expected from BAO. We show that stacking selected shells, we can find their characteristic density profile. Conclusions. We delineate a new feature of the cosmic web, the BAO shells. As these are real spatial structures, the BAO phenomenon can be studied in detail by examining those shells. |
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Address |
[Arnalte-Mur, P.; Martinez, V. J.] Univ Valencia, Astron Observ, Valencia 46071, Spain, Email: pablo.arnalte-mur@durham.ac.uk |
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Publisher |
Edp Sciences S A |
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English |
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ISSN |
0004-6361 |
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Conference |
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Notes |
WOS:000305803300021 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1088 |
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Permanent link to this record |