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Newsletter English February/March 2023 Print E-mail

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ICRANet Newsletter
February/March 2023


1. Chinese scientist Yu Wang appointed President of the International Centre for Relativistic Astrophysics (ICRA), February 28, 2023

It is our great pleasure to announce that Prof. Yu Wang has been appointed as the new President of the International Center for Relativistic Astrophysics (ICRA) on the occasion of the ICRA Assembly Meeting, held on February 28, 2023, after voting and deliberation.

On this occasion, Prof. Massimo Della Valle, Chairperson of the ICRANet Scientific Committee, delivered a speech in support of the nomination of Prof. Yu Wang, as well as a scientific presentation on ICRA titled “From the birth of Relativistic Astrophysics to the discovery and comprehension of Gamma-Ray Bursts to the new era of Black Hole physics and Artificial Intelligence”. The text of the speech can be read at the following link: www.icranet.org/documents/presentationDellaValle.pdf.

ICRA (International Centre for Relativistic Astrophysics) was founded in 1985 by Prof. Remo Ruffini together with Riccardo Giacconi (Nobel Prize for Physics 2002), Abdus Salam (Nobel Prize for Physics 1979), Paul Boyton (University of Washington), George Coyne (former director of the Vatican observatory), Francis Everitt (Stanford University), Fang Li-Zhi (University of Science and Technology of China). It became a legal entity in 1991 with the Ministerial Decree 22/11/1991 from the Ministry of Education, Universities and Research. Members of ICRA are Stanford University, the University of Science and Technology of China,The World Academy of Sciences (TWAS), the Specola Vaticana, the Space Telescope Institute, the Abdus Salam International Center for Theoretical Physics (ICTP), the University of Washington, the University Campus Bio-Medico of Rome, the University of Insubria and the University of Udine. The main mission of ICRA is to promote the exchange and development of astrophysics in all countries.

After his appointment, Prof. Wang made a presentation to the assembly of his scientific career and publications, which can be found at the following link: www.icranet.org/documents/presentationWang.pdf.

Prof. Yu Wang is a native of Suzhou, Jiangsu Province, born in 1985. He has a BSc in Physics from Southeast University, an MSc in Astrophysics from the Purple Mountain Observatory, Chinese Academy of Sciences, and a PhD in Astrophysics from the University of Rome, Italy. He has been working in astrophysics at ICRANet (International Center for Relativistic Astrophysics Network) since 2015 and at the National Astronomical Observatory of Italy (INAF) since 2019, and has been appointed the President of ICRA in 2023.

The ICRA Assembly congratulated Prof. Yu Wang on his appointment as the new President of ICRA, fostering his research on Black Holes, Gamma-Ray Bursts and promoting the application of new technologies such as deep learning in astronomy and astrophysics. It looked forward that Prof. Yu Wang would further expand ICRA's exchanges and collaborations with universities and institutes around the world.
For the press release on ICRANet website:
For the press releases on:

2. Seminar of Prof. Remo Ruffini at INAF IAPS, March 15, 2023, Rome (Italy)

On March 15, 2023, Prof. Ruffini, Director of ICRANet, has been invited to give a seminar at the Institute for Space Astrophysics and Planetology (IAPS) of INAF in Rome (Italy). This seminar has been inserted in the series of the “Rome Joint Astrophysics Colloquia (Rome JAC)”, co organized by IAPS, the Astronomical Observatory of Rome and the Physics department of the University of Rome Tor Vergata and regularly held every third Wednesday of the month.
Fig. 1: Prof. Ruffini on the occasion of his seminar at the IAPS INAF on March 15, 2023 together with INAF members and part of the ICRANet group. Fig. 2: From the left to the right: Prof. Rahim Moradi (ICRANet Faculty Professor), Prof. Ruffini, Prof. Enrico Costa (INAF), Dr Fatemeh Rastegar Nia (ICRANet researcher), Prof. Carlo Luciano Bianco (ICRANet Faculty Professor), Prof. Wang Yu (ICRANet Faculty Professor) and Shurui Zhang (ICRANet visiting student from USCT – China).
On that occasion, Prof. Ruffini presented a talk titled “New Physics and Astrophysics from GRBs”, chaired by Prof. Enrico Costa; here it is the abstract:

The observations of Ic supernovae (Ic/SNe) occurring after the prompt emission of long gamma-ray bursts (GRBs) are addressed within the binary-driven hypernova (BdHN) model. Here, the GRBs originate from a binary composed of a ∼ 10 M carbon-oxygen (CO) star and a companion neutron star (NS). We assume these same progenitors originate the Ic/SN. The binary evolution depends strongly on the binary period, Pbin. The trigger, given by the CO core collapse, for Pbin of up to a few hours leads to an Ic/SN with a fast-spinning NS (νNS) at its center. For Pbin ∼ 4–5 min, BdHN I occur with 37 energies 1052–1054 erg, a contribution by the black hole (BH) created by the NS companion collapse, originates the Mev/GeV radiations. The ∼ 1 millisecond νNS originates, by synchrotron radiation, the X-ray afterglow. For Pbin∼ 10 min, BdHN II occurs with energies of 1050–1052 erg. For Pbin∼ hours, BdHN III occurs with energies below 1050 erg. The 1–1000 ms νNS, in all BdHNe, originates the X-ray afterglow by synchrotron emission. The SN Ic follows an independent evolution, becoming observable by the nickel decay after the GRB prompt emission. We report 24 Ic/SNe associated with BdHNe, their optical peak luminosity and their time of occurrence are similar and independent of the associated GRBs. We give four examples of BdHNe and their associated hypernovae. We approach, for the first time, new physical processes in BdHNe; we identify seven episodes and their signatures in their spectra.

As soon as available, the video of the seminar will be published on the ICRANet YouTube channel at the following link: https://www.youtube.com/channel/UCU19scWRGvlIiKBcN1QXCRQ

3. ICRANet participation at the “Conference for scientific and space attachés: scientific diplomacy for the growth of Italy, March 6-7, 2023, Padua (Italy)

On March 6-7, 2023, Prof. Ruffini, Director of ICRANet, together with Prof. Yu Wang, ICRANet Faculty Professor, took part at the “Conference for scientific and space attachés: scientific diplomacy for the growth of Italy”, organized by the Italian Ministry of Foreign Affairs and International Cooperation (MAECI) and held at the University of Padua (Italy).

After the opening ceremony, the first day of the meeting saw the participation and intervention of eminent Italian personalities, such as the Italian Minister of Foreign Affairs and International Cooperation H. E. Antonio Tajani, the Italian Minister for Business and Made in Italy H.E. Adolfo Urso, the Rector of the University of Padua Prof. Daniela Mapelli and the astronaut Luca Parmitano. The first day ended with a roundtable on the subject “Space: the new frontier of internationalization”, with a relevant intervention of the Edmondo Cirielli, Italian Deputy Minister of Foreign Affairs with appointment to Space, and the participation, among others, of Prof. Giorgio Saccoccia, president of ASI as well as of Prof. Marco Tavani, President of INAF.

During the second day of the meeting, two roundtables have been held. The first one on the subject “Research as the engine of the competitiveness of the country system” saw the participation of the Italian Minister of University and ResearchH.E. Anna Maria Bernini as well as of the former Italian Minister of Education, University and Research, now President of CNR Dr Maria Chiara Carrozza. The second roundtable was on the subject “The reply of Italian innovation to the new global challenges”.

On the occasion of that meeting, Prof. Ruffini and Prof. Wang met the Min. Plen. Shen Jianlei (Ministry Counselor for Science and Technology of the Chinese Embassy in Italy), Dr Francesco Ubertini (President of Cineca), Dr Maria Chiara Carrozza (former Italian Minister of Education, University and Research, now President of CNR) and H.E. Min. Anna Maria Bernini (Italian Minister of University and Research).

Fig. 3 from the left to the right: Min. Plen. Shen Jianlei (Ministry Counselor for Science and Technology of the Chinese Embassy in Italy), Dr Francesco Ubertini (President of Cineca), Dr Maria Chiara Carrozza (former Italian Minister of Education, University and Research, now President of CNR), H.E. Min. Anna Maria Bernini (Italian Minister of University and Research), prof. Remo Ruffini (Director of ICRANet) and Prof. Yu Wang (ICRANet faculty Professor and new President of ICRA).

4. Nicolaus Copernicus and Gregory III, February 24, 2023, online meeting

On February 24, 2023, Prof. Costantino Sigismondi, organized the online meeting “Nicolaus Copernicus and Gregory III” at the Ateneo Pontificio Regina Apostolorum, Istituto Scienza e Fede in Rome, in collaboration with ICRANet and the Astrophysical Observatory of Asiago. The meeting has also been broadcasted via Zoom and Youtubewith the opening remarks by Prof. Remo Ruffini, Director of ICRANet, as well as by Prof. Rafael Pascual, Director of ISF.
Fig. 4: Prof. Remo Ruffini delivering his opening speech at the meeting “Nicolaus Copernicus and Gregory III”, chaired by Prof. Costantino Sigismondi and held on February 24, 2023 both at the Ateneo Pontificio Regina Apostolorum, Istituto Scienza e Fede in Rome and online.

Members of the Organizing Committee of the meeting have been Cesare Barbieri (University of Padua), Giuseppe Giudice (University of Neaples Federico II), Paolo Ochner (Astrophysical Observatory of Asiago and University of Padua), Cosimo Palagiano (Accademia dei Lincei), Rafael Pascual (APRA/ISF), Elena Piccoli (High School Antonio Scarpa Motta di Livenza), Tiziana Pompa (High School Galilei in Pescara), Remo Ruffini (Director of ICRANet) and Costantino Sigismondi (APRA and ICRANet).

Nicolaus Copernicus was born on February 19, 1473 in Torun (Poland) and, with the publication of “De Revolutionibus Orbium Coelestium” he became the most influent astronomer of the modern history. 50 years ago, the University of Padua dedicated to him the biggest telescope (still today) in Italy, namely the Cima Ekar telescope.

The cosmogony was changing its reference system, abandoning the geocentric viewpoint. Astronomy was still based on the meridian positional and topocentric observations and for additional two centuries continued to prefer the pinhole to the telescope for the solar astrometry. An experiment jointly performed in Rome and Motta di Livenza on the angular measurement of the meridian arc shows us how the pinhole is still valid. The entrance of the Sun in the sign of Pisces on February 18, 2023 at h 23:34 is a geocentric phenomenon, concerning the ecliptic reference system, which has the vernal equinox as zero and the orbit belonging to the Sun as axis of the longitudes.

Julius Caesar promulgated the reform of the Calendar in 46 b.c., taking as value for the tropical year 365 days and 6 hours, under which the Sun comes back to the vernal equinox. In 325, the vernal equinox retreated on March 21 and this date has been fixed as ecclesiastical equinox by the fathers of the Council of Nicaea. The retreat of the equinox date continued to the rhythm of 3 days every 4 centuries and, at the times of Copernicus, anticipated of 10 days. The astronomers measured the equinoxes and the zodiac signs timing the meridian passages of the Sun in comparison with the stars. They knew since Ipparco (150 b. C.) that the equinox retreated compared to the direction that the Sun has on the background of the starry sky. If the Sun goes from Aquarius to Pisces, the equinox goes in the opposite sense but much more slowly, making a full circle in 26.000 years and covering an entire sign in around 2.000 years. Astronomically, the birth date of Copernicus fell 10 days closer to the spring equinox, so in the sign of Pisces and in the zodiac constellation of Aquarius, the last one visible only in case of total eclipse.

The Reformation of the Calendar was issued on February 24, 1582 by the Pope Gregory XIII, because the real equinox was occurring on March 11, instead of March 21 according to Nicaea’s Council prescriptions of 325 AD on the Easter Computus. The Gregorian Reform solved the real equinox date problem, known by all scholarly people (e.g. Dante Alighieri). Enacted on February 24, 1582 from Villa Mondragone in Frascati with the “Bolla Inter Gravissimas” the precession continues but the vernal equinox date (from Ver = spring in Latin) remained fixed on March 21, according to the Nicaenian tradition for the computation of the Easter date. Therefore, the precession continues to change the constellations on which the Sun is projected on a fixed date: 4.000 years ago it should have been on the background of Pisces, 2.000 years ago retreated in the constellation of Aquarius, and in few centuries it will be in Capricorn, but the zodiacal signs remain those of the Greek-Babylonian tradition to which Ptolemy wanted to conform. It’s just a change in the reference system, as happens for the compass which, when looks at North-East is Grecale but from Rome to North-East we don’t go to Greece: the original reference was to Malta.

In that meeting, Prof. Sigismondi presented how could the effectiveness of the Reform could be seen measuring the entry of the Sun in Pisces this year 2023 by using the historical meridian lines of Saint Peter’s square in Vatican (1586-1817) and of Santa Maria degli Angeli (1702), using also the meridian passage of Sirius, as already done by the Egyptians more than 4.000 years ago. With the latter instrument, it has also been taken the angular measure of the meridian arc from Rome to Motta di Livenza, repeating the Eratosthenes experiment with the Cassini corrections for the atmospheric refraction, obtaining the Earth’s circumference within 1%, and showing why the giant pinhole meridian lines have been preferred for solar astrometry up to two centuries after the invention of the telescope.

Several talks have been presented during the meeting, namely on the “Copernican conference in Santa Maria Deglia Angeli on February 18, 2023”, on “The entrance in the Pisces at the sundial in Saint Peter Square on February 18, 2023”, on “The transit of Sirius to the sundial in Saint Peter Square on February 18, 2023”, on “The passage of the Sun to the Clementine meridian line on Sunday February 19, 2023”, on “The Bolla Inter Gravissimas translated in Italian”, on “The astronomer Copernicus by Jan Matejko (1873)” and on “The lunar algorithm of the Gregorian calendar”. Prof. Sigismondi also illustrated the positional data of the solar image on the Clementine meridian line on February 18 – 19, 2023 and the linear interpolation for the entrance in Pisces.
Fig. 5: the Sun projected on the marble marquetry of the Pisces of Francesco Tedeschi in Santa Maria degli Angeli in Rome on February 18, 2023. The center of this frame is at 5198 mm from the reference 160. Fig. 6: Sirius on the left of the Vatican obelisk on February 18, 2023 at h 20:57:15, observed from the meridian line.
For more information on the meeting, including the videos, the scientific rationale and the podcast material: http://www.icranet.org/index.php?option=com_content&task=view&id=1487

5. Announcement of the 18th Italian- Korean Symposium (IK18), June 19 – 23, 2023, Pescara (Italy)
It gives us great pleasure to announce the 18thItalian-Korean Symposium on Relativistic Astrophysics that will be held from June19 to 23, 2023 in person at ICRANet center in Pescara (Italy) and online. The meeting has been co organized by Kunsan National University, CQUeST and Sogang University (on the Korean side) and, on the italian side, by ICRANet. Members of IK18 Italian Committee are Remo Ruffini (Director of ICRANet, ICRA), Carlo Luciano Bianco (ICRA, ICRANet), Massimo Della Valle (Capodimonte Astronomical Observatory, INAF, ICRANet), Luca Izzo (Capodimonte Astronomical Observatory, INAF), Paolo Giommi (ASI), Roy Patrick Kerr (ICRANet), Liang Li (ICRANet), Rahim Moradi (ICRANet), Jorge A. Rueda H. (ICRANet, University of Ferrara), Narek Sahakyan (Director of ICRANet center in Armenia), Gregory Vereshchagin (ICRANet), Yu Wang (ICRANet) and Shesheng Xue (ICRANet). Members of IK18 Korean Committee are Stefano Scopel (CQUeST, Sogang University), Bum-Hoon Lee (CQUeST, Sogang University), Wontae Kim (CQUeST, Sogang University), Jeong-Hyuck Park (CQUeST, Sogang University), Wonwoo Lee (CQUeST, Sogang University), Sang Pyo Kim (Kunsan National University), Bogeun Gwak (Dongguk University), Imtak Jeon (APCTP), Hyungwon Lee (Inje University), Changhwan Lee (Pusan National University) and Hyeong Chan Kim (Korea National university of Transportation).

The Italian-Korean Symposia on Relativistic Astrophysics is a series of biannual meetings, alternatively organized in Italy and in Korea since 1987, with support from Korea Science and Engineering Foundation (KOSEF), Consiglio Nazionale delle Ricerche (CNR), ICRANet and hosting institutes. The main purpose of this symposium is to accelerate the exchange between Italian and Korean scientists, especially young researchers.
In addition to the topics in Relativistic Astrophysics traditionally discussed at the IK meetings (e.g.Gamma-Ray bursts and compact stars, high energy cosmic rays, dark energy and dark matter, general relativity, black holes and new physics related to cosmology), particular attention will be given in this IK18 meeting to the energy extraction processes from the Kerr black hole by fission of massive particles (Penrose process), by classical electrodynamic processes and by quantum processes. In all cases, the role of the irreducible mass will be evidenced in characterizing the efficiency of the emission processes. Examples from active galactic nuclei and Gamma-Ray bursts will be illustrated.

The scientific program of the meeting is in preparation and more details about the event will be posted on its webpage: https://indico.icranet.org/event/7/ .

6. Third announcement of the 5th Zeldovich meeting, June 12-17, 2023, Yerevan (Armenia)

We are very happy to inform that the list of confirmed invited talks for the 5th Zeldovich meeting, which will be held from June 12 – 17, 2023 in Yerevan (Armenia) now includes:
  • “Fermionic dark matter: theory & phenomenology” by Carlos Raúl Argüelles, Universidad Nacional de La Plata, Argentina;
  • “Hubble Tension challenge in the modern cosmology: possible solutions” by Gennady Bisnovatyi-Kogan, Space Research Institute (IKI), Russia;
  • “Pair-balance model for relativistic shocks and its application to astrophysical sources” by Evgeny Derishev, Institute of Applied Physics, Russia;
  • “Quantum sensing – the key technology for further gravitational experiments in space” by Hansjoerg Dittus, University of Bremen, Germany;
  • “Neutrino Telescope Baikal-GVD: Status and Nearest Future” by Zhan-Arys Dzhilkibaev, Institute for Nuclear Research of the Russian Academy of Sciences, Russia;
  • “SRG/eROSITA all-sky survey: from solar flares and neutrino sources to cosmology” by Marat Gilfanov, Max-Planck Institute for Astrophysics, Germany and IKI, Russia;
  • “Neutron Stars as Strong Field QED Laboratory” by Sang Pyo Kim, Kunsan National University, South Korea;
  • “New quantum technologies and gravity” by Claus Laemmerzahl, University Bremen, Germany;
  • “Discoveries from FAST” by Di Li, National Astronomical Observatories of China, China;
  • “Black hole induced star formation in the early universe” by Felix Mirabel, CEA Saclay, France;
  • “Selected Studies of Cosmic and Gamma Rays with the MAGIC telescopes” by Razmik Mirzoyan, Max-Planck-Institute for Physics, Germany;
  • “Influence of a plasma on the shadow of black holes” by Volker Perlick, ZARM, University Bremen, Germany;
  • “An electrodynamic process to extract the rotational energy of a Kerr black hole” by Jorge Armando Rueda Hernandez, ICRANet, Italy;
  • “The Imaging X-ray Polarimetry Explorer (IXPE) results from the first 1.5 years of observation” by Paolo Soffitta, IAPS, INAF, Rome, Italy;
  • “New developments in the inflationary scenario” by Alexei Starobinsky, Landau Institute for Theoretical Physics, Russia;
  • “The spectral signatures of BHs versus NSs” by Lev Titarchuk, University di Ferrara, Italy and Astro Space Center, Lebedev Physical Institute, Russia;
  • “Highlights of the Insight-HXMT X-ray Astronomy Satellite” by Shuang-Nan Zhang, Institute of High Energy Physics, China.
The early bird registration fee is 300 euro (100 euro for students) and it ends up on 1 of May 2023. Starting from that date, the registration fee will be 400 euro (150 euro for students).
For the website of the meeting: http://www.icranet.org/zeldovich5
For the poster of the meeting: https://indico.icranet.org/event/6/attachments/382/560/poster.pdf

7. Scientific visits to ICRANet

• Antonio Enea Romano (Universidad de Antioquia UDEA), February 2 – 6, 2023
• Narek Sahakyan (Director of ICRANet Armenia), February 6 – 12, 2023
• Soroush Shakeri (Isfahan University of Technology), March 28, 2023 - ongoing

During their visit, those scientists had an opportunity to discuss their scientific research and to have fruitful exchange of ideas with other researchers from ICRANet and from different parts of the world.

8. Recent publications

Liang Li, Yu Wang, Felix Ryde, Asaf Pe'er, Bing Zhang, Sylvain Guiriec, Alberto J. Castro-Tirado, D. Alexander Kann, Magnus Axelsson, Kim Page, A Cosmological Fireball with 16% Gamma-Ray Radiative Efficiency, published in The Astrophysical Journal Letters, Volume 944, Number 2 on February 23, 2023.

Gamma-ray bursts (GRBs) are the most powerful explosions in the universe. How efficiently the jet converts its energy to radiation is a long-standing problem, which is poorly constrained. The standard model invokes a relativistic fireball with a bright photosphere emission component. A definitive diagnosis of GRB radiation components and the measurement of GRB radiative efficiency require prompt emission and afterglow data, with high resolution and wide band coverage in time and energy. Here, we present a comprehensive temporal and spectral analysis of the TeV-emitting bright GRB 190114C. Its fluence is one of the highest for all the GRBs that have been detected so far, which allows us to perform a high-resolution study of the prompt emission spectral properties and their temporal evolutions, down to a timescale of about 0.1 s. We observe that each of the initial pulses has a thermal component contributing ∼20% of the total energy and that the corresponding temperature and inferred Lorentz factor of the photosphere evolve following broken power-law shapes. From the observation of the nonthermal spectra and the light curve, the onset of the afterglow corresponding to the deceleration of the fireball is considered to start at ∼6 s. By incorporating the thermal and nonthermal observations, as well as the photosphere and synchrotron radiative mechanisms, we can directly derive the fireball energy budget with little dependence on hypothetical parameters, measuring a ∼16% radiative efficiency for this GRB. With the fireball energy budget derived, the afterglow microphysics parameters can also be constrained directly from the data.

Liang Li, J. A. Rueda, R. Moradi, Y. Wang, S. S. Xue, and R. Ruffini, Self-similarities and Power Laws in the Time-resolved Spectra of GRB 190114C, GRB 130427A, GRB 160509A, and GRB 160625B, published in The Astrophysical Journal, Volume 945, Number 1 on March 1, 2023.

Binary-driven hypernova (BdHN) models have been adopted to explain the observed properties of long gamma-ray bursts (GRBs). Here, we perform a comprehensive data analysis (temporal and spectral analysis, GeV emission, and afterglow) on GRB 130427A, GRB 160509A, and GRB 160625B. We identify three specific episodes characterized by different observational signatures and show that these episodes can be explained and predicted to occur within the framework of the BdHNe I model, as first observed in GRB 190114C and reported in an accompanying paper. Episode 1 includes the “SN-rise” with the characteristic cutoff power-law spectrum; Episode 2 is initiated by the moment of formation of the black hole, coincident with the onset of the GeV emission and the ultrarelativistic prompt emission phase, and is characterized by a cutoff power law and blackbody spectra; Episode 3 is the “cavity,” with its characteristic featureless spectrum.

Liang Li, Revisiting the Spectral-Energy Correlations of GRBs with Fermi Data I: Model-wise Properties, accepted for publication in The Astrophysical Journal Supplement Series.

Gamma-ray bursts (GRBs) exhibit a diversity of spectra. Several spectral models (e.g., Band, cutoff power-law, and blackbody) and their hybrid versions (e.g., Band+blackbody) have been widely used to fit the observed GRB spectra. Here, we attempt to collect all the bursts detected by Fermi-GBM with known redshifts from July 2008 to May 2022, motivated to (i) provide a parameter catalog independent from the official Fermi/GBM team and (ii) achieve a “clean” model-based GRB spectral- energy correlation analysis. A nearly complete GRB sample was created, containing 153 such bursts (136 long gamma-ray bursts and 17 short gamma-ray bursts). Using the sample and by performing detailed spectral analysis and model comparisons, we investigate two GRB spectral-energy correlations: the cosmological rest-frame peak energy (Ep,z) of the νFνprompt emission spectrum correlated with (i) the isotropic-bolometric-equivalent emission energy Eϓ,iso (the Amati relation), and (ii) the isotropic- bolometric-equivalent peak luminosity Lp,iso (the Yonetoku relation). From a linear regression analysis, a tight correlation between Ep,z and Eϓ,iso (and Lϓ,iso) is found for both the Band-like and CPL-like bursts. More interestingly, the CPL-like bursts do not fall on the Band-like burst Amati and Yonetoku correlations, suggesting distinct radiation processes, and pointing towards the fact that these spectral-energy correlations are tightly reliant on the model-wise properties.
Sahakyan, N., Harutyunyan, G., Israyelyan, D., Origin of multiwavelength emission from flaring high redshift blazar PKS 0537-286, published on Monthly Notices of the Royal Astronomical Society, Volume 521, Issue 1, May 2023 on February 20, 2023.
The high redshift blazars powered by supermassive black holes with masses exceeding 109 M have the highest jet power and luminosity and are important probes to test the physics of relativistic jets at the early epochs of the Universe. We present a multifrequency spectral and temporal study of high redshift blazar PKS 0537−286 by analyzing data from Fermi-LAT, NuSTAR Swift XRT, and UVOT. Although the time averaged γ-ray spectrum of the source is relatively soft (indicating the high-energy emission peak is below the GeV range), several prominent flares were observed when the spectrum hardened and the luminosity increased above 1049 erg s−1. The X-ray emission of the source varies in different observations and is characterized by a hard spectrum ≤1.38 with a luminosity of >1047 erg s−1. The broad-band spectral energy distribution in the quiescent and flaring periods was modelled within a one-zone leptonic scenario assuming different locations of the emission region and considering both internal (synchrotron radiation) and external (from the disc, broad-line region, and dusty torus) photon fields for the inverse Compton scattering. The modeling shows that the most optimistic scenario, from the energy requirement point of view, is when the jet energy dissipation occurs within the broad-line region. The comparison of the model parameters obtained for the quiescent and flaring periods suggests that the flaring activities are most likely caused by the hardening of the emitting electron spectral index and shifting of the cut-off energy to higher values.
MAGIC Collaboration, MAGIC observations provide compelling evidence of hadronic multi-TeV emission from the putative PeVatron SNR G106.3+2.7, published in Astronomy & Astrophysics, Volume 671, March 2023 on February 28, 2023.

Context. Certain types of supernova remnants (SNRs) in our Galaxy are assumed to be PeVatrons, capable of accelerating cosmic rays (CRs) to ~ PeV energies. However, conclusive observational evidence for this has not yet been found. The SNR G106.3+2.7, detected at 1–100 TeV energies by different γ-ray facilities, is one of the most promising PeVatron candidates. This SNR has a cometary shape, which can be divided into a head and a tail region with different physical conditions. However, in which region the 100 TeV emission is produced has not yet been identified because of the limited position accuracy and/or angular resolution of existing observational data. Additionally, it remains unclear as to whether the origin of the γ-ray emission is leptonic or hadronic.

Aims. With the better angular resolution provided by new MAGIC data compared to earlier γ-ray datasets, we aim to reveal the acceleration site of PeV particles and the emission mechanism by resolving the SNR G106.3+2.7 with 0.1° resolution at TeV energies.
Methods. We observed the SNR G106.3+2.7 using the MAGIC telescopes for 121.7 h in total – after quality cuts – between May 2017 and August 2019. The analysis energy threshold is ~0.2 TeV, and the angular resolution is 0.07−0.1°. We examined the γ-ray spectra of different parts of the emission, whilst benefitting from the unprecedented statistics and angular resolution at these energies provided by our new data. We also used measurements at other wavelengths such as radio, X-rays, GeV γ-rays, and 10 TeV γ-rays to model the emission mechanism precisely.

Results. We detect extended γ-ray emission spatially coincident with the radio continuum emission at the head and tail of SNR G106.3+2.7. The fact that we detect a significant γ-ray emission with energies above 6.0 TeV from only the tail region suggests that the emissions above 10 TeV detected with air shower experiments (Milagro, HAWC, Tibet ASγ and LHAASO) are emitted only from the SNR tail. Under this assumption, the multi-wavelength spectrum of the head region can be explained with either hadronic or leptonic models, while the leptonic model for the tail region is in contradiction with the emission above 10 TeV and X-rays. In contrast, the hadronic model could reproduce the observed spectrum at the tail by assuming a proton spectrum with a cutoff energy of ~1 PeV for that region. Such high-energy emission in this middle-aged SNR (4−10 kyr) can be explained by considering a scenario where protons escaping from the SNR in the past interact with surrounding dense gases at present.

Conclusions. The γ-ray emission region detected with the MAGIC telescopes in the SNR G106.3+2.7 is extended and spatially coincident with the radio continuum morphology. The multi-wavelength spectrum of the emission from the tail region suggests proton acceleration up to ~PeV, while the emission mechanism of the head region could either be hadronic or leptonic.

Link: https://doi.org/10.1051/0004-6361/202244931

S. Campion, J. D. Uribe-Suárez, J. D. Melon Fuksman, J. A. Rueda, MeV, GeV and TeV Neutrinos from Binary-Driven Hypernovae, published in Symmetry, 15, 412 on February 3, 2023.

We analyze neutrino emission channels in energetic (≳1052 erg) long gamma-ray bursts within the binary-driven hypernova model. The binary-driven hypernova progenitor is a binary system composed of a carbon-oxygen star and a neutron star (NS) companion. The gravitational collapse leads to a type Ic supernova (SN) explosion and triggers an accretion process onto the NS. For orbital periods of a few minutes, the NS reaches the critical mass and forms a black hole (BH). Two physical situations produce MeV neutrinos. First, during the accretion, the NS surface emits neutrino–antineutrino pairs by thermal production. We calculate the properties of such a neutrino emission, including flavor evolution. Second, if the angular momentum of the SN ejecta is high enough, an accretion disk might form around the BH. The disk’s high density and temperature are ideal for MeV-neutrino production. We estimate the flavor evolution of electron and non-electron neutrinos and find that neutrino oscillation inside the disk leads to flavor equipartition. This effect reduces (compared to assuming frozen flavor content) the energy deposition rate of neutrino–antineutrino annihilation into electron–positron (e+e) pairs in the BH vicinity. We then analyze the production of GeV-TeV neutrinos around the newborn black hole. The magnetic field surrounding the BH interacts with the BH gravitomagnetic field producing an electric field that leads to spontaneous e+e pairs by vacuum breakdown. The e+e plasma self-accelerates due to its internal pressure and engulfs protons during the expansion. The hadronic interaction of the protons in the expanding plasma with the ambient protons leads to neutrino emission via the decay chain of π-meson and μ-lepton, around and far from the black hole, along different directions. These neutrinos have energies in the GeV-TeV regime, and we calculate their spectrum and luminosity. We also outline the detection probability by some current and future neutrino detectors.

Link: https://doi.org/10.3390/sym15020412

Wang, Yu, Becerra, L. M., Fryer, C. L., Rueda, J. A., Ruffini, R., GRB 171205A: Hypernova and Newborn Neutron Star, published in The Astrophysical Journal, Volume 945, Issue 2 on March 9, 2023.

GRB 171205A is a low-luminosity, long-duration gamma-ray burst (GRB) associated with SN 2017iuk, a broad-line type Ic supernova (SN). It is consistent with having been formed in the core collapse of a widely separated binary, which we have called the binary-driven hypernova of type III. The core collapse of the CO star forms a newborn NS (νNS) and the SN explosion. Fallback accretion transfers mass and angular momentum to the νNS, here assumed to be born non-rotating. The accretion energy injected into the expanding stellar layers powers the prompt emission. The multiwavelength power-law afterglow is explained by the synchrotron radiation of electrons in the SN ejecta, powered by energy injected by the spinning νNS. We calculate the amount of mass and angular momentum gained by the νNS, as well as the νNS rotational evolution. The νNS spins up to a period of 47 ms, then releases its rotational energy powering the synchrotron emission of the afterglow. The paucity of the νNS spin explains the low-luminosity characteristic and that the optical emission of the SN from the nickel radioactive decay outshines the optical emission from the synchrotron radiation. From the νNS evolution, we infer that the SN explosion had to occur at most 7.36 h before the GRB trigger. Therefore, for the first time, the analysis of the GRB data leads to the time of occurrence of the CO core collapse leading to the SN explosion and the electromagnetic emission of the GRB event.
Krut, A., Argüelles, C. R., Chavanis, P. -H., Rueda, J. A., Ruffini, R., Galaxy Rotation Curves and Universal Scaling Relations: Comparison between Phenomenological and Fermionic Dark Matter Profiles, published in The Astrophysical Journal, Volume 945, Issue 1, on March 1, 2023.

Galaxies show different halo scaling relations such as the radial acceleration relation, the mass discrepancy acceleration relation (MDAR), or the dark matter (DM) surface density relation. At difference with traditional studies using phenomenological ΛCDM halos, we analyze the above relations assuming that DM halos are formed through a maximum entropy principle (MEP) in which the fermionic (quantum) nature of the DM particles is dully accounted for. For the first time, a competitive DM model based on first physical principles, such as (quantum) statistical-mechanics and thermodynamics, is tested against a large data set of galactic observables. In particular, we compare the fermionic DM model with empirical DM profiles: the Navarro–Frenk–White (NFW) model, a generalized NFW model accounting for baryonic feedback, the Einasto model, and the Burkert model. For this task, we use a large sample of 120 galaxies taken from the Spitzer Photometry and Accurate Rotation Curves data set, from which we infer the DM content to compare with the models. We find that the radial acceleration relation and MDAR are well explained by all the models with comparable accuracy, while the fits to the individual rotation curves, in contrast, show that cored DM halos are statistically preferred with respect to the cuspy NFW profile. However, very different physical principles justify the flat inner-halo slope in the most-favored DM profiles: while generalized NFW or Einasto models rely on complex baryonic feedback processes, the MEP scenario involves a quasi-thermodynamic equilibrium of the DM particles.

Link: https://doi.org/10.3847/1538-4357/acb8bd

H. Barzegar, M. Bigdeli, G. H. Bordbar, and B. Eslam Panah, Stable three-dimensional (un)charged AdS gravastars in gravity’s rainbow, published in European Physical Journal C 83, 151 on February 16, 2023.

In this work, we study the three-dimensional AdS gravitational vacuum stars (gravastars) in the context of gravity’s rainbow theory. Then we extend it by adding the Maxwell electromagnetic field. We compute the physical features of gravastars, such as proper length, energy, entropy, and junction conditions. Our results show that the physical parameters for charged and uncharged states depend significantly on rainbow functions. Besides from charged state, they also depend on the electric field. Finally, we explore the stability of thin shell of three-dimensional (un)charged AdS gravastars in gravity’s rainbow. We show that the structure of thin shell of these gravastars may be stable and is independent of the type of matter.

Link: https://doi.org/10.1140/epjc/s10052-023-11295-3

B. Eslam Panah and M. E. Rodrigues, Topological phantom AdS black holes in F(R) gravity,accepted for publication in European Physical Journal C (March 2023).

In this paper, we obtain exact phantom (A)dS black hole solutions in the context of F(R) gravity with topological spacetime in four dimensions. Then, we study the effects of different parameters on the event horizon. In the following, we calculate the conserved and thermodynamic quantities of the system and check the first law of thermodynamics for these kinds of black holes. Next, we evaluate the local stability of the topological phantom (A)dS black holes in F(R) gravity by studying the heat capacity and the geometrothemodynamic, where we show that the two approaches agree. We extend our study and investigate global stability by employing the Gibbs potential and the Helmholtz free energy. In addition, the effects of different parameters on local and global stabilities will be highlighted.

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