Astroparticle Physics最新文献

{"title":"Energy spectra of the first TGE observed on Zugspitze by the SEVAN light detector compared with the energetic TGE observed on Aragats","authors":"A. Chilingarian ,&nbsp;T. Karapetyan ,&nbsp;B. Sargsyan ,&nbsp;J. Knapp ,&nbsp;M. Walter ,&nbsp;T. Rehm","doi":"10.1016/j.astropartphys.2024.102924","DOIUrl":"10.1016/j.astropartphys.2024.102924","url":null,"abstract":"<div><p><span>The energy spectra<span> of Thunderstorm ground enhancement (TGE) electrons and gamma rays are the key evidence for proving the origin of enhanced </span></span>particle fluxes<span> from thunderclouds. Till now, the electron energy spectrum was measured only by the Aragats large scintillation spectrometer ASNT. We changed the electronics board of the SEVAN detector installed at the Umwelt-Forschungs-Station (UFS, Schneefernerhaus, 2650 m asl) to allow these vital measurements near the top of the Zugspitze. The new electronics of the SEVAN detector, supplied with logarithmic ADC, for the energy release measurements up to 50 MeV (the thickness of the spectrometric scintillator is 25 cm). Thus, by measuring energy releases well above 3 MeV, we unambiguously separate Radon progeny gamma radiation from the electrons and gamma-ray relativistic runaway avalanches. Using the different energy release histograms allows for separating charged and neutral particles, enabling the disentangling of electron and gamma-ray energy spectra. On May 23, 2023, the first TGE was registered on Zugspitze by the SEVAN detector. The gamma-ray flux enhancement was 44%, corresponding to the observed count rate peak enhancement of 44σ. The gamma-ray energy spectrum was recovered, maximum energy is 60 MeV. On the same day, a large TGE was observed on Aragats. The TGE maximum flux overpasses the fair-weather flux by 207%, equivalent to a 1-minute peak significance of 400σ. Maximum energy of electrons is 50 MeV, gamma rays – 45 MeV. In this context, we will explore and explain the new capabilities of the SEVAN detector installed on Zugspitze and the rearranged similar detector on Aragats. We also present and compare electron and gamma-ray energy spectra from Aragats TGE and gamma-ray energy spectrum from Zugspitze.</span></p></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"156 ","pages":"Article 102924"},"PeriodicalIF":3.5,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139083150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Proof of principle for template synthesis approach for the radio emission from vertical extensive air showers","authors":"Mitja Desmet ,&nbsp;Stijn Buitink ,&nbsp;Tim Huege ,&nbsp;David Butler ,&nbsp;Ralph Engel ,&nbsp;Olaf Scholten","doi":"10.1016/j.astropartphys.2023.102923","DOIUrl":"10.1016/j.astropartphys.2023.102923","url":null,"abstract":"<div><p><span>The radio detection technique of cosmic ray air showers has gained renewed interest in the last two decades. While the radio experiments are very cost-effective to deploy, the Monte-Carlo simulations required to analyse the data are computationally expensive. Here we present a proof of concept for a novel way to synthesise the radio emission from extensive air showers in simulations. It is a hybrid approach which uses a single microscopic Monte-Carlo simulation, called the origin shower, to generate the radio emission from a target shower with a different longitudinal evolution, primary particle type and energy. The method employs semi-analytical relations which only depend on the shower parameters to transform the radio signals in the simulated antennas. We apply this method to vertical air showers with energies ranging from </span><span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>17</mn></mrow></msup><mspace></mspace><mtext>eV</mtext></mrow></math></span> to <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>19</mn></mrow></msup><mspace></mspace><mtext>eV</mtext></mrow></math></span> and compare the results with CoREAS simulations in two frequency bands, namely the broad [20, 500] <span><math><mtext>MHz</mtext></math></span> band and a more narrow one at [30, 80] <span><math><mtext>MHz</mtext></math></span><span>. We gauge the synthesis quality using the maximal amplitude and energy fluence contained in the signal. We observe that the quality depends primarily on the difference in </span><span><math><msub><mrow><mi>X</mi></mrow><mrow><mtext>max</mtext></mrow></msub></math></span> between the origin and target shower. After applying a linear bias correction, we find that for a shift in <span><math><msub><mrow><mi>X</mi></mrow><mrow><mtext>max</mtext></mrow></msub></math></span> of less than 150 <span><math><mrow><mtext>g</mtext><mo>/</mo><msup><mrow><mtext>cm</mtext></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span>, template synthesis has a bias of less than 2% and a scatter up to 6%, both in amplitude, on the broad frequency range. On the restricted [30, 80] <span><math><mtext>MHz</mtext></math></span> range the bias is similar, but the spread on amplitude drops down to 3%. These fluctuations are on the same level as the intrinsic scatter we observe in Monte-Carlo ensembles. We therefore surmise the observed scatter in amplitude to originate from intrinsic shower fluctuations we do not explicitly account for in template synthesis.</p></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"157 ","pages":"Article 102923"},"PeriodicalIF":3.5,"publicationDate":"2023-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139068039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Autonomous observation, control, data acquisition and monitoring of MACE telescope","authors":"Anushri Jain,&nbsp;Shikha Srivastava,&nbsp;Mahesh P․,&nbsp;J. Deshpande,&nbsp;Padmini S․","doi":"10.1016/j.astropartphys.2023.102922","DOIUrl":"10.1016/j.astropartphys.2023.102922","url":null,"abstract":"<div><p>Major Atmospheric Cherenkov Experiment (MACE) is a large telescope commissioned at Ladakh region of India. It consists of many subsystems operating in synchronization<span> to perform successful observations. The paper introduces a robust, concise and autonomous operator console to operate, control and monitor the entire experiment, providing workflow management, autonomous schedule-based observation, orchestration of data acquisition and monitoring of telemetry data, while maintaining safety of subsystems. Using a synchronised controller-observer pattern the highly-automated operator console carries out the entire observation on a single click from either local or from remote geographic locations. Remote operation of the telescope from BARC, Mumbai allowed pre-commissioning tests, troubleshooting and upgradation of the system from a more convenient environment.</span></p></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"157 ","pages":"Article 102922"},"PeriodicalIF":3.5,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139067932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glitching pulsars as gravitational wave sources","authors":"B. Haskell ,&nbsp;D.I. Jones","doi":"10.1016/j.astropartphys.2023.102921","DOIUrl":"10.1016/j.astropartphys.2023.102921","url":null,"abstract":"<div><p><span>Spinning neutron stars, when observed as pulsars, are seen to undergo occasional spin-up events known as glitches. Despite several decades of study, the physical mechanisms responsible for glitches are still not well understood, but probably involve an interplay between the star’s outer elastic crust, and the </span>superfluid<span> and superconducting core that lies within. Glitches will be accompanied by some level of gravitational wave emission. In this article, we review proposed models that link gravitational wave emission to glitches, exploring both short duration burst-like emission, and longer-lived signals. We illustrate how detections (and in some cases, non-detections) of gravitational signals probe both the glitch mechanism, and, by extension, the behaviour of matter at high densities.</span></p></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"157 ","pages":"Article 102921"},"PeriodicalIF":3.5,"publicationDate":"2023-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139051874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic topology and photon spheres in the hyperscaling violating black holes","authors":"Jafar Sadeghi ,&nbsp;Mohammad Ali S. Afshar ,&nbsp;Saeed Noori Gashti ,&nbsp;Mohammad Reza Alipour","doi":"10.1016/j.astropartphys.2023.102920","DOIUrl":"10.1016/j.astropartphys.2023.102920","url":null,"abstract":"&lt;div&gt;&lt;p&gt;&lt;span&gt;It was shown that a standard ring of light can be imagined outside the event horizon for stationary rotating four-dimensional black holes with axial symmetry using the topological method (Cunha, 2020; Wei and Shao-Wen, 2020). Based on this concept, in this paper, we investigate the topological charge and the conditions of existence of the photon sphere (PS) for a hyperscaling violation (HSV) black hole with various values of the parameters of this model. Then, after carrying out a detailed analysis, we show the conventional topological classes viz &lt;/span&gt;&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for the mentioned black hole and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;span&gt; for the naked singularities. &lt;/span&gt;&lt;em&gt;Also, we propose a new topological class for naked singularities (&lt;/em&gt;&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;em&gt;) with respect to&lt;/em&gt; &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;em&gt;. We also determined that&lt;/em&gt; &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;em&gt;, it either shows a naked singularity form with total topological charge&lt;/em&gt; &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; &lt;em&gt;or has no solution. Therefore, we have the black hole solution only in&lt;/em&gt; &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Then, we will use two different methods, namely the temperature (Duan’s topological current &lt;span&gt;&lt;math&gt;&lt;mi&gt;Φ&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt;-mapping theory) and the generalized Helmholtz free energy method, to study the topological classes of our black hole. By considering the black hole mentioned, we discuss the critical and zero points (topological charges and topological numbers) for different parameters of hyperscaling violating black holes, such as (&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;¯&lt;/mo&gt;&lt;/mover&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;span&gt;) and other free parameters, and study their thermodynamic topology. We observe that for a given value of the parameters &lt;/span&gt;&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;mi&gt;z&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, &lt;span&gt;&lt;math&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;θ&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;¯&lt;/mo&gt;&lt;/mover&gt;&lt;/math&gt;&lt;/span&gt;, and other free parameters, there exist two total topological charges &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;Q&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mi&gt;o&lt;/mi&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mi&gt;a&lt;/mi&gt;&lt;mi&gt;l&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; with the same phase structure for the &lt;span&gt;&lt;math&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; method and total topological numbers &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mi&gt;W&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for the generalized Helmholtz free energy method. Additionally, we summarize the results for each study as photon sphere, temperature, and generalized Helmholtz free energy in some f","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"156 ","pages":"Article 102920"},"PeriodicalIF":3.5,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139031341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ancestral spin information in gravitational waves from black hole mergers","authors":"O. Barrera,&nbsp;I. Bartos","doi":"10.1016/j.astropartphys.2023.102919","DOIUrl":"10.1016/j.astropartphys.2023.102919","url":null,"abstract":"<div><p><span>The heaviest black holes discovered through gravitational waves have masses that are difficult to explain with current standard </span>stellar models. This discrepancy may be due to a series of hierarchical mergers, where the observed black holes are themselves the products of previous mergers. Here we present a method to estimate the masses and spins of previous generations of black holes based on the masses and spins of black holes in a binary. Examining the merger GW190521, we find that assuming black hole spins that are consistent with those of merger remnants will alter the reconstructed ancestral spins when compared to results with uninformed priors. At the same time, the inclusion of black hole spins does not significantly affect the mass distributions of the ancestral black holes.</p></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"156 ","pages":"Article 102919"},"PeriodicalIF":3.5,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138567469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Forecasts analysis on varying-α theories from gravitational wave standard sirens","authors":"L.R. Colaço ,&nbsp;R.F.L. Holanda ,&nbsp;Rafael C. Nunes ,&nbsp;J.E. Gonzalez","doi":"10.1016/j.astropartphys.2023.102911","DOIUrl":"https://doi.org/10.1016/j.astropartphys.2023.102911","url":null,"abstract":"<div><p><span>Motivated by future gravitational waves observations, we perform forecasts analysis to constrain a possible time variation of the fine structure constant (</span><span><math><mi>α</mi></math></span><span>) within the context of the so-called runaway dilaton model. For this purpose, some gravitational-wave standard sirens mock data within the perspective of Einstein Telescope and LISA mission were considered jointly with current strong gravitational lensing systems observations. We find that future standard sirens observations can also play an important role in the search for possible variations of </span><span><math><mi>α</mi></math></span> within the methodology presented in this work.</p></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"155 ","pages":"Article 102911"},"PeriodicalIF":3.5,"publicationDate":"2023-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49761351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enabling kilonova science with Nancy Grace Roman Space Telescope","authors":"Igor Andreoni ,&nbsp;Michael W. Coughlin ,&nbsp;Alexander W. Criswell ,&nbsp;Mattia Bulla ,&nbsp;Andrew Toivonen ,&nbsp;Leo P. Singer ,&nbsp;Antonella Palmese ,&nbsp;E. Burns ,&nbsp;Suvi Gezari ,&nbsp;Mansi M. Kasliwal ,&nbsp;R. Weizmann Kiendrebeogo ,&nbsp;Ashish Mahabal ,&nbsp;Takashi J. Moriya ,&nbsp;Armin Rest ,&nbsp;Dan Scolnic ,&nbsp;Robert A. Simcoe ,&nbsp;Jamie Soon ,&nbsp;Robert Stein ,&nbsp;Tony Travouillon","doi":"10.1016/j.astropartphys.2023.102904","DOIUrl":"https://doi.org/10.1016/j.astropartphys.2023.102904","url":null,"abstract":"<div><p><span><span><span><span>Binary neutron star mergers and neutron star–black hole mergers are multi-messenger sources that can be detected in </span>gravitational waves and in </span>electromagnetic radiation<span>. The low electron fraction of neutron star merger ejecta favors the production of heavy elements such as </span></span>lanthanides and actinides via rapid neutron capture (</span><span><math><mi>r</mi></math></span>-process). The decay of these unstable nuclei powers an infrared-bright transient called a “kilonova”. The discovery of a population of kilonovae will allow us to determine if neutron star mergers are the dominant sites for <span><math><mi>r</mi></math></span><span><span>-process element nucleosynthesis, constrain the equation of state<span><span> of nuclear matter, and make independent measurements of the Hubble constant. The Nancy Grace Roman Space Telescope (Roman) will have a unique combination of depth, near-infrared sensitivity, and wide </span>field of view. These characteristics will enable Roman’s discovery of GW counterparts that will be missed by </span></span>optical telescopes, such as kilonova that are associated with large distances, high lanthanide fractions, high binary mass-ratios, large dust extinction in the line of sight, or that are observed from equatorial viewing angles. In preparation for Roman’s launch and operations, our analysis suggests to (i) make available a rapid (</span><span><math><mrow><mo>∼</mo><mn>1</mn></mrow></math></span> week) Target of Opportunity mode for GW follow-up; (ii) include observations of the High Latitude Time-Domain survey footprint in at least two filters (preferably the F158 and F213 filters) with a cadence of <span><math><mrow><mo>≲</mo><mn>8</mn></mrow></math></span> days; (iii) operate in synergy with Rubin Observatory. Following these recommendations, we expect that 1–6 kilonovae can be identified by Roman via target of opportunity observations of well localized (<span><math><mrow><mi>A</mi><mo>&lt;</mo><mn>10</mn></mrow></math></span> <!--> <!-->deg<span><math><msup><mrow></mrow><mrow><mn>2</mn></mrow></msup></math></span>, 90% C.I.) neutron star mergers during 1.5 years of the LIGO-Virgo-KAGRA fifth (or <span><math><mo>∼</mo></math></span>4–21 in during the sixth) observing run. A sample of 5–40 serendipitously discovered kilonovae can be collected in a 5-year high latitude survey.</p></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"155 ","pages":"Article 102904"},"PeriodicalIF":3.5,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49710379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tensor fluctuations in the early universe","authors":"F. Melia","doi":"10.1016/j.astropartphys.2023.102876","DOIUrl":"10.1016/j.astropartphys.2023.102876","url":null,"abstract":"<div><p><span><span>In standard inflationary cosmology, scalar and tensor perturbations grew as the Universe expanded and froze when their wavelengths exceeded the Hubble horizon, producing a tell-tale signature in the fluctuation spectrum and amplitude of the cosmic microwave background (CMB). But there are now very good reasons to examine whether structure formation could also have begun via the seeding of </span>quantum fluctuations in a non-inflationary field. In this </span><em>Letter</em><span>, we study and compare the scalar and tensor modes produced in these two scenarios, and demonstrate that upcoming observations to measure the B-mode polarization of the CMB may be able to differentiate between them. Whereas both scalar and tensor modes should be observable if the field was inflationary, only scalar modes would be present in the CMB if it were not. Should gravity be purely classical, however, the tensor modes would have avoided canonical quantization in all cases, resulting in unmeasurably weak gravitational waves. A non-detection of B-mode polarization would thus not completely rule out inflation.</span></p></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"152 ","pages":"Article 102876"},"PeriodicalIF":3.5,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48310613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of cosmogenic activation above ground for the DarkSide-20k experiment","authors":"A. Elersich ,&nbsp;P. Agnes ,&nbsp;I. Ahmad ,&nbsp;S. Albergo ,&nbsp;I.F.M. Albuquerque ,&nbsp;T. Alexander ,&nbsp;A.K. Alton ,&nbsp;P. Amaudruz ,&nbsp;M. Atzori Corona ,&nbsp;M. Ave ,&nbsp;I.Ch. Avetisov ,&nbsp;O. Azzolini ,&nbsp;H.O. Back ,&nbsp;Z. Balmforth ,&nbsp;A. Barrado-Olmedo ,&nbsp;P. Barrillon ,&nbsp;A. Basco ,&nbsp;G. Batignani ,&nbsp;V. Bocci ,&nbsp;W.M. Bonivento ,&nbsp;M.P. Zykova","doi":"10.1016/j.astropartphys.2023.102878","DOIUrl":"https://doi.org/10.1016/j.astropartphys.2023.102878","url":null,"abstract":"<div><p>The activation of materials due to exposure to cosmic rays may become an important background source for experiments investigating rare event phenomena. DarkSide-20k, currently under construction at the Laboratori Nazionali del Gran Sasso, is a direct detection experiment for galactic dark matter particles, using a two-phase liquid-argon Time Projection Chamber (TPC) filled with 49.7 tonnes (active mass) of Underground Argon (UAr) depleted in ³⁹Ar. Despite the outstanding capability of discriminating <span><math><mi>γ</mi></math></span>/<span><math><mi>β</mi></math></span> background in argon TPCs, this background must be considered because of induced dead time or accidental coincidences mimicking dark-matter signals and it is relevant for low-threshold electron-counting measurements. Here, the cosmogenic activity of relevant long-lived radioisotopes induced in the experiment has been estimated to set requirements and procedures during preparation of the experiment and to check that it is not dominant over primordial radioactivity; particular attention has been paid to the activation of the 120 t of UAr used in DarkSide-20k. Expected exposures above ground and production rates, either measured or calculated, have been considered in detail. From the simulated counting rates in the detector due to cosmogenic isotopes, it is concluded that activation in copper and stainless steel is not problematic. The activity of ³⁹Ar induced during extraction, purification and transport on surface is evaluated to be 2.8% of the activity measured in UAr by DarkSide-50 experiment, which used the same underground source, and thus considered acceptable. Other isotopes in the UAr such as ³⁷Ar and ³H are shown not to be relevant due to short half-life and assumed purification methods.</p></div>","PeriodicalId":55439,"journal":{"name":"Astroparticle Physics","volume":"152 ","pages":"Article 102878"},"PeriodicalIF":3.5,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49709788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}