306 research outputs found
Blind search for intraday gamma-ray transients
No full text<p>It is a basic reproduction package for the paper titled "A blind search for intraday gamma-ray transients with Fermi-LAT: Detection of GRB and solar emissions" by Dmitry Prokhorov and Anthony Moraghan. This package includes products for reproducing the results of the paper, <a href="https://arxiv.org/abs/2401.08946" target="_blank" rel="noopener nofollow noreferrer">https://arxiv.org/abs/2401.08946</a>, including a set of scripts as well as final csv files and and fits maps. The description of data products is in the file, README.md. The paper was accepted for publication in A&A on April 19, 2024.</p>
Fermi-LAT transients in the Galactic plane
No full textIt is a basic reproduction package for the paper titled "An update on Fermi-LAT transients in the Galactic plane, including strong activity of Cygnus X-3 in mid-2020" by Dmitry Prokhorov and Anthony Moraghan. This package includes data products for reproducing the main results of the paper, https://arxiv.org/abs/2209.12461. The description of data products is in the file, readme.txt. Please, feel free to contact Dmitry Prokhorov, email: d.prokhorov at uva.nl, if you have any questions about the data products. The paper is accepted for publication in MNRAS on November 18, 2022. The software used for this analysis is publicly available at https://zenodo.org/record/4739389 and Fermi-LAT data are publicly available at https://fermi.gsfc.nasa.gov/ssc/data/access
Evidence for a shock-compressed magnetic field in the northwestern rim of Vela Jr. from X-ray polarimetry
No full textProkhorov, Dmitry A. et al.-- Full list of authors: Prokhorov, Dmitry A.; Yang, Yi-Jung; Ferrazzoli, Riccardo; Vink, Jacco; Slane, Patrick; Costa, Enrico; Silvestri, Stefano; Zhou, Ping; Bucciantini, Niccolò; Di Marco, Alessandro; Weisskopf, Martin C.; Baldini, Luca; Doroshenko, Victor; Ehlert, Steven R.; Heyl, Jeremy; Kaaret, Philip; Kim, Dawoon E.; Marin, Frédéric; Mizuno, Tsunefumi; Ng, Chi-Yung; Pesce-Rollins, Melissa; Sgrò, Carmelo; Soffitta, Paolo; Swartz, Douglas A.; Tamagawa, Toru; Xie, Fei; Agudo, Iván; Antonelli, Lucio A.; Bachetti, Matteo; Baumgartner, Wayne H.; Bellazzini, Ronaldo; Bianchi, Stefano; Bongiorno, Stephen D.; Bonino, Raffaella; Brez, Alessandro; Capitanio, Fiamma; Castellano, Simone; Cavazzuti, Elisabetta; Chen, Chien-Ting; Ciprini, Stefano; De Rosa, Alessandra; Del Monte, Ettore; Di Gesu, Laura; Di Lalla, Niccolò; Donnarumma, Immacolata; Dovčiak, Michal; Enoto, Teruaki; Evangelista, Yuri; Fabiani, Sergio; García, Javier A.; Gunji, Shuichi; Iwakiri, Wataru; Jorstad, Svetlana G.; Karas, Vladimir; Kislat, Fabian; Kitaguchi, Takao; Kolodziejczak, Jeffery J.; Krawczynski, Henric; La Monaca, Fabio; Latronico, Luca; Liodakis, Ioannis; Maldera, Simone; Manfreda, Alberto; Marinucci, Andrea; Marscher, Alan P.; Marshall, Herman L.; Massaro, Francesco; Matt, Giorgio; Mitsuishi, Ikuyuki; Muleri, Fabio; Negro, Michela; O'Dell, Stephen L.; Omodei, Nicola; Oppedisano, Chiara; Papitto, Alessandro; Pavlov, George G.; Peirson, Abel L.; Perri, Matteo; Petrucci, Pierre-Olivier; Pilia, Maura; Possenti, Andrea; Poutanen, Juri; Puccetti, Simonetta; Ramsey, Brian D.; Rankin, John; Ratheesh, Ajay; Roberts, Oliver J.; Romani, Roger W.; Spandre, Gloria; Tavecchio, Fabrizio; Taverna, Roberto; Tawara, Yuzuru; Tennant, Allyn F.; Thomas, Nicholas E.; Tombesi, Francesco; Trois, Alessio; Tsygankov, Sergey S.; Turolla, Roberto; Wu, Kinwah; Zane, SilviaSynchrotron X-ray emission has been detected from nearly a dozen young supernova remnants (SNRs). X-rays of synchrotron origin exhibit linear polarization in a regular, non-randomly oriented magnetic field. The significant polarized X-ray emission from four such SNRs has already been reported on the basis of observations with the Imaging X-ray Polarimetry Explorer (IXPE). The magnetic-field structure as derived from IXPE observations is radial for Cassiopeia A, Tycho's SNR, and SN 1006, and tangential for RX J1713.7‑3946. The latter together with the recent detection of a tangential magnetic field in SNR 1E 0102.2-7219 by the Australia Telescope Compact Array in the radio band shows that tangential magnetic fields can also be present in young SNRs. Thus, the dichotomy in polarization between young and middle-aged SNRs (radial magnetic fields in young SNRs, but tangential magnetic fields in middle-aged SNRs), previously noticed in the radio band, deserves additional attention. The present analysis of IXPE observations determines, for the first time, a magnetic-field structure in the northwestern rim of Vela Jr, also known as RX J0852.0‑4622, and provides a new example of a young SNR with a tangential magnetic field. © The Authors 2024The Imaging X-ray Polarimetry Explorer (IXPE) is a joint
US and Italian mission. The US contribution is supported by the National
Aeronautics and Space Administration (NASA) and led and managed by its
Marshall Space Flight Center (MSFC), with industry partner Ball Aerospace
(contract NNM15AA18C). The Italian contribution is supported by the Italian
Space Agency (Agenzia Spaziale Italiana, ASI) through contract ASI-OHBI2022-13-I.0, agreements ASI-INAF-2022-19-HH.0 and ASI-INFN-2017.13-H0,
and its Space Science Data Center (SSDC) with agreements ASI-INAF-2022-14-
HH.0 and ASI-INFN 2021-43-HH.0, and by the Istituto Nazionale di Astrofisica
(INAF) and the Istituto Nazionale di Fisica Nucleare (INFN) in Italy. This
research used data products provided by the IXPE Team (MSFC, SSDC, INAF,
and INFN) and distributed with additional software tools by the High-Energy
Astrophysics Science Archive Research Center (HEASARC) at NASA Goddard Space Flight Center (GSFC). D.P. acknowledges support by the European
Research Council, ERC Starting grant “Mapping Highly-Energetic Messengers
throughout the Universe”, under contract no. 949555. R.F., E.Co., A.D.M., P.So.,
S.F., F.L.M., F.Mu. are partially supported by MAECI with grant CN24GR08
“GRBAXP: Guangxi-Rome Bilateral Agreement for X-ray Polarimetry in Astrophysics”. N.B. was supported by the INAF MiniGrant “PWNnumpol–Numerical
Studies of Pulsar Wind Nebulae in the Light of IXPE”.Peer reviewe
An analysis of Fermi-LAT observations of the outskirts of the Coma cluster of galaxies
No full textWe analyse the data from the Fermi-Large Area Telescope in order to search for a ring-like gamma-ray structure around the Coma cluster. The ring-like structure has recently been suggested to be detected with VERITAS at energies higher than 220 GeV and could possibly be associated with an accretion shock. Our analysis of the Fermi data is performed at energies > 100 MeV and we find no detection of this structure in the Fermi data. We derive the 95 per cent upper limit on the flux from the region covering the proposed ring-like structure. The derived upper limit on the flux at > 100 MeV cannot be incorporated with the detection of an accretion shock wave around Coma at the significance of 4.5 sigma by VERITAS at very high energies, if the production mechanism of the gamma-ray emission generates a photon spectrum with a power index of 2 in the broad energy band. The model of gamma-ray emission induced by ultrahigh-energy protons can reconcile the results of the VERITAS and Fermi observations.</p
The century of service to science: a fundamental publication on the monograph “History of V. I. Vernadsky Crimean Federal University in documents and photographs”
No full textA review of the monograph “History of V. I. Vernadsky Crimean Federal University in documents and photographs” (Simferopol, 2018), sponsored by the staff of the Museum of History of V. I. Vernadsky Crimean Federal University. This is a structural subdivision headed by A. A. Nepomnyashchiy, the Doctor of Historical Sciences, Professor, Head of the Department of Historical Regional Studies and Local History of V. I. Vernadsky Crimean Federal University. The relevance of the study is due to the fact that, despite of the significant number of publications on the history of this educational institution, the true history of the university in the scientific sense of the word, has not yet been published. The publication is prepared by the museum staff and based on the materials obtained in the course of painstaking research, which are stored in the archives of Simferopol, Moscow, Makhachkala and St. Petersburg. The monograph attempted to summarize the data found by the authors in the archives, as well as the information available in the literature today regarding the history of one of the oldest universities in southern Russia. The monograph “The history of V. I. Vernadsky Crimean Federal University in documents and photographs” has become a worthy continuation of publications about the history not only of the university itself, but also of the entire scientific school of the Crimea. I would like to express the hope that these books will be in demand among the scientists, professors and university students, and all those who are interested in the history of the Crimea
“On the Performance of a Rite of Marriage under Threat of Execution by a Gazzan...”: The Problem of Interethnic and Interfaith Marriages in the Karaite Communities of Crimea in the Late 19th – early 20th Centuries
No full textUpper bounds on matter-antimatter admixture from gamma-ray observations of colliding clusters of galaxies with the Fermi Large Area Telescope
No full textWe examined whether significant constraints on matter-antimatter admixture can be derived from gamma-ray observations of colliding clusters of galaxies with Fermi-LAT. We selected ten known systems of colliding clusters of galaxies for the analysis and computed the upper bounds on matter-antimatter admixture in these systems, which range from 7×10−9 to 2×10−6. This allowed us to exclude a symmetric universe on scales of order ∼20 Mpc at the confidence level of 99.9%. Adopting the number of systems of colliding galaxy clusters from the Marenostrum Universe cosmological simulation, we checked if the Fermi-LAT second source catalog contains a sufficient number of gamma-ray sources to provide us with the required number of sources possibly associated with pp¯annihilation from cluster-anticluster collisions. We found that a matter-antimatter-symmetric universe is strongly ruled out on scales of order ∼20 Mpc if a matter-antimatter admixture in these bullet-like systems is of f≳10−5, and on scales of order ∼400 Mpc if f≳10−4.</p
X-ray polarization detection of Cassiopeia A with IXPE
No full textData reproduction package for “X-ray polarization detection of Cassiopeia A with IXPE” (Vink, Prokhorov, Ferrazzoli et al. 2022) published by the Astrophysical Journal
Abstract of the publication
We report on a ∼ 5σ detection of polarized 3–6 keV X-ray emission from the supernova remnant Cassiopeia A with the Imaging X-ray Polarimetry Explorer (IXPE). The overall polarization degree of 1.8±0.3% is detected by summing over a large region, assuming circular symmetry for the polarization vectors. The measurements imply an average polarization degree for the synchrotron component of ∼ 2.5%, and close to 5% for the X-ray synchrotron-domimated forward-shock region. These numbers are based on an assessment of the thermal and non-thermal radiation contributions, for which we used a detailed spatial-spectral model based on Chandra X-ray data. A pixel-by-pixel search for polarization provides a few tentative detections from discrete regions at the ∼ 3σ confidence level. Given the number of pixels, the significance is insufficient to claim a detection for individual pixels, but implies considerable turbulence on scales smaller than the angular resolution. Cas A’s X-ray continuum emission is dominated by synchrotron radiation from regions within 1017 cm of the forward- and reverse shocks. We find that i) the measured polarization angle corresponds to a radially-oriented magnetic field, similar to what has been inferred from radio observations; ii) the X-ray polarization degree is lower than in the radio band (∼ 5%). Since shock compression should impose a tangential magnetic field structure, the IXPE results imply that magnetic-fields are reoriented within ∼ 1017 cm of the shock. If the magnetic-field alignment is due to locally enhanced acceleration near quasi-parallel shocks, the preferred X-ray polarization angle suggests a size of 3 × 1016 cm for cells with radial magnetic fields
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