# # # #
Newsletter French August/September 2020 Print E-mail

Logo ICRANet Logo CAPES Logo Erasmus Mundus Logo FAPERJ Logo MAE

ICRANet Newsletter

Bulletin ICRANet
Août - Septembre 2020

1. Vidéos des conférences récentes données par les membres de la Faculté ICRANet
Talk of Prof. Remo Ruffini at IWARA 2020 meeting Talk of Prof. Jorge Rueda at IWARA 2020 meeting
Talk of Prof. Remo Ruffini at The Fourth Zeldovich virtual meeting Talk of Prof. Gregory Vereshchagin at The Fourth Zeldovich virtual meeting
Talk of Prof. Jorge Rueda at The Fourth Zeldovich virtual meeting Talk of Prof. Remo Ruffini at the 14th International Conference on Gravitation, Astrophysics and Cosmology

2. Multiwavelength Study of High-Redshift Blazars

The new article coauthored by N. Sahakyan, D. Israyelyan, G. Harutyunyan, M. Khachatryan and S. Gasparyan “Multiwavelength Study of High-Redshift Blazars”, is published in Monthly Notices of the Royal Astronomical Society on 17 August 2020.

Figure 1. Spectra of some blazars.

Blazars harboring supermassive black holes are valuable sources for studying the relativistic outflows and formation and propagation of relativistic jets. In this context, the high redshift blazars (z>2.5) are of particular interest; they are among the most powerful non- explosive astrophysical sources in the Universe. Their study can shed light on the further understanding of the cosmological evolution of blazars and supermassive black holes and also on the evolution of relativistic jets across different cosmic epochs. Motivated by the large number of detected high redshift γ-ray emitting blazars, with the aim to characterize their multiwavelength emission properties, an intense broadband study of all the thirty-three known γ-ray blazars beyond redshift 2.5 is performed. In order to characterize the physical properties of the considered sources, Fermi Large Area Telescope γ-ray data accumulated during 2008-2018, as well as X-ray and optical/UV data from the observations with both Swift X-ray Telescope and Ultraviolet and Optical Telescope in the previous fifteen years are analyzed. This allowed collecting unprecedented data in the optical/UV, X-ray, and γ-ray bands, which is used to constrain the multiwavelength spectral energy distributions (SEDs), see Fig. 1. Then, through modeling of these SEDs within a one-zone leptonic scenario (assuming that the X-ray and γ-ray emissions are produced from inverse Compton scattering of synchrotron and dusty torus photons), the physical parameters characterizing the sources (disc luminosity, black hole mass, etc.) and their jets (e.g., the distribution of underlying electrons, magnetic field, power, etc.) are derived, allowing a quantitative discussion and investigation of the state of plasma in these powerful jets.
Time variability in different energy bands is particularly important. In the X-ray band, only the emission of PKS 0438-43, B2 0743+25 and TXS 0222+185 is found to vary in different Swift XRT observations whereas in the γ-ray band, the emission is variable for fourteen sources: the flux of B3 1343+451 and PKS 0537-286 changes in sub-day scales, that of PKS 0347-211 and PKS 0451-28 in day scales, while the γ-ray variability of the others is in week or month scales. Such rapid variability in high energy band is in agreement with recently proposed model for the inner engine of AGNs by Rueda, J.A., Ruffini, R., "The blackholic quantum", Eur. Phys. J. C 80, 300 (2020), see https://doi.org/10.1140/epjc/s10052-020-7868-z.

The article is available here: https://doi.org/10.1093/mnras/staa2477
ArXiv e-print: https://arxiv.org/abs/2008.09675

3. Geodesic motion of S2 and G2 as a test of the fermionic dark matter nature of our Galactic core

The paper “Geodesic motion of S2 and G2 as a test of the fermionic dark matter nature of our Galactic core”, co-authored by E.A. Becerra-Vergara, C.R. Argüelles, A. Krut, J.A. Rueda, and R. Ruffini has been published by Astronomy & Astrophysics on September 4, 2020. In this paper, the evidence is given on the possibility of different interpretation of observational data of the motion of S2 and G2 objects near the Galactic center. Within this interpretation, which is perfectly consistent with General Relativity, the compact object is not a black hole but a condensation of dark matter.


Link to the paper: https://www.aanda.org/articles/aa/abs/2020/09/aa35990-19/aa35990-19.html
Link to ArXiv e-print: https://arxiv.org/abs/2007.11478

4. Nouveau accord de coopération entre ICRANet-Université de Mazandaran, 24 Aout 2020


Le 24 Aout, a été signé un accord de coopération entre l'ICRANet et l'Université de Mazandaran (Iran) par le Prof. Kourosh Nozari (Président de l'Université de Mazandaran), par le Prof. Mahmoud Azizi (Directeur du Bureau de coopération internationale et scientifique de l'Université de Mazandaran) et par le Prof. Remo Ruffini (Directeur d'ICRANet). Les principales activités conjointes qui seront développées dans le cadre de cet accord comptent: la promotion des activités de recherche et dobservation dans le champ de lastrophysique relativiste; la collaboration entre des membres de la Faculté, des chercheurs, des post-doctorat fellows et des étudiants; lorganisation de séminaires, conférences, workshops, cours de formations et de recherche, et publications conjointes. L'accord demeurera valide pour 5 années.
Pour consulter le texte de l'accord:

5. 14ème Conférence Internationale sur la Gravitation, l'Astrophysique et la Cosmologie (ICGAC 14), 17-21 Aout 2020

4 L'édition 2020 de la conférence ICGAC 14 a eu lieu, virtuellement, du 17 au 21 Aout auprès de la National Central University, Jhongli, à Taiwan. Le Prof. Ruffini, Directeur d'ICRANet, a donné une présentation titrée "The geodesic motion of S2 and G2 as a test of the fermionic dark matter nature of our galactic core", tandis que le Prof. Gregory Vereshchagin, Professeur de la Faculté d'ICRANet, a donné une presentation titrée "Diffusive photospheres and thermal emission in early afterglows of gamma-ray bursts". L'ICGAC 14 est une série de conférences biennales sur la Gravitation, l'Astrophysique et la Cosmologie, qui a lieu dans la région Asie-Pacifique, ayant comme but la promotion de la coopération entre les pays membres et dans le contexte international, des études de haut niveau sur des thèmes crucials ainsi que l'encouragement des jeunes physiciens dans ces domaines.
Pour le site web de la conférence: https://icgac14.phy.ncu.edu.tw

6. Vidéoconférence IWARA 2020. From Quarks to Cosmo, 6-12 Septembre 2020


Le Prof. Remo Ruffini a été invité à donner une présentation plénière à l'occasion de la vidéoconférence IWARA 2020, qui a eu lieu du 6 au 12 Septembre à Mexico. Le Prof. Ruffini a donné une présentation sur la "Discovery of energy extraction from a Kerr Black Hole by discrete Black-Holic quanta in GRB 190114C, GRB 130427A, GRB 160509A and GRB 160625B".
Abstract: Almost fifty years after the paper "Introducing the Black Hole" by Ruffini and Wheeler and the Black Hole (BH) mass energy formula by Christodoulou, Ruffini and Hawking, we can finally assert that we have been observing the moment of creation of a BH in the BdHN I in GRB 190114C, GRB 130427A, GRB 160509A and GRB 160625B, with the corresponding rotational energy extraction process. The first appearance of the Supernova, the SN-rise, triggering the BdHN has been identified. The hypercritical accretion on the SN ejecta on the new NS (νNS) created in the SN, is shown to originate the X-ray afterglow observed by the NASA Neil-Gehrels SWIFT satellite (SWIFT). The hypercritical accretion of the SN on the NS binary companion in the BdHN I model leads to the formation of the newly formed BH. The onset of the GeV radiation coinciding with the BH formation has revealed self similar structures in the time resolved spectral analysis of all sources. Consequently, we find evidence for quantized-discrete-emissions in all sources, with energy quanta of 1037 ergs with repetition time of 10-14 sec. GRBs are the most complex systems ever successfully analyzed in Physics and Astrophysics, and they may well have a role in the appearance of life in the Cosmos. These results have been made possible by a long-lasting theoretical activity, a comprehensive unprecedented high quality data analysis, an observational multi-messenger effort by the astronomical, the physical and the space research communities. This observational effort is well epitomized by the original Vela Satellites, the NASA Compton space mission (CGRO), the Italo-Dutch Beppo SAX satellite, the Russian Konus Wind Satellite, the SWIFT satellite, the Italian AGILE satellite, the NASA FERMI mission and most recently the Chinese satellite HXMT. These space missions have been assisted by radio and optical equally outstanding observational facilities from the ground.
The website of the conference: https://indico.cern.ch/event/822124/

7. Vidéoconférence 4ème Zeldovich meeting, 7-11 Septembre 2020

Le 4ème Zeldovich meeting a été organisé par l'ICRANet et par l'Académie nationale des Sciences de Biélorussie. Il a eu lieu virtuellement du 7 à l'11 Septembre 2020.

Figure 2. Final greetings at the end of the meeting.

Le nombre de participants enregistrés, environ 150 personnes, représente un grand succès pour les Zeldovich meetings. Des participants de tous les continents avec différents fuseaux horaires étaient connectés. Chaque jour il y avait 3 sessions: 2 pour le matin et une dans l'après-midi. A la séance du matin ont pris partie surtout des conférenciers asiatiques, africains et européens, tandis que dans celle de l'après-midi ont pris partie surtout des participants de l'Amérique du Nord et du Sud. Les séances portaient sur les sujet suivants: Gravitation, Sursauts Gamma, Relativité Générale et Quantum, Missions spatiales, Champ magnétique, Relativité Générale et Autres Théories, Univers Primitif, Horizons des Trous Noirs, Astrophysique Multi-Messenger, Gravitation, Astrophysique et Particules Elémentaires, structure à grande échelle de lUnivers, Etoiles Rayonnantes et Matière Sombre dans l'Univers, Exoplanètes et Astrobiologie, Matière Sombre et Energie Sombre, Supernovae et Gravitation. En total, 89 travaux ont été présentés, entre eux 30 étaient invités. Plusieurs résultats observationnels ont été abordés, en particulier: les premiers résultats par l'Observatoire orbital SRG et la mission HXMT, les observations au sol des Neutrinos par l'Observatoire ICECube, les Sursaut Gamma à haute énergie par les télescopes MAGIC, les rapides observations optiques par le réseau MASTER, les observations du centre galactique par la collaboration GRAVITY, ainsi que l'ombre des Trous noirs dans M87*, les nouvelles observations et l'analyse des données des Sursauts Gamma, les Exoplanètes et la structure à grande échelle de lUnivers. En plus, le progrès théorique dans la théorie des Sursauts Gamma et le mécanisme des Supernovae, le Dynamo magnétique dans les Galaxies, la Gravité quantique, les théories alternatives de la Gravité, la Physique de Neutrino, l'origine de la Matière Sombre, les distorsions spectrales CMB et beaucoup d'autres sujets ont été discutés.
Les remarques finales, résumant les nouveaux et importants résultats scientifiques présentés le long de la conférence, ont était fait par l'Académicien Sergei Kilin, par le Vice-président de l'Académie nationale des Sciences de Biélorussie NASB, par le Prof. Remo Ruffini, Directeur d'ICRANet et par le Prof. Gregory Vereshchagin.
Les proceedings du 4ème Zeldovich meeting seront publiés dans la revue avec arbitrage Astronomy Reports, la principale revue russe sur l'Astronomie et l'Astrophysique. le site web de la revue: https://www.springer.com/journal/11444.
Cette conférence internationale est la 4ème dédiée à Ya. B. Zeldovich. Les conférences précédentes ont eu lieu du 23 au 27 Avril 2018 à Minsk, du 20 au 23 Avril 2009 à Minsk (co-organisée par l'ICRANet et la Belarusian State University BSU, pour célébrer aussi le 2009 Année de l'Astronomie) et du 11 au 14 Mars 2014, pour célébrer le 100ème anniversaire de Ya. B. Zeldovich.
Les vidéos des séances sont disponibles sur le canal YouTube d'ICRANet:
Les présentations des conférenciers sont disponibles sur la page web de la conférence: http://www.icranet.org/index.php?option=com_content&task=view&id=1339
Le site web de la conférence: http://www.icranet.org/zeldovich4

8. 106th SIF National Congress, September 14 – 18, 2020

Du 14 au 18 Septembre, a eu lieu, virtuellement, le 106 ème Congrès National de la Société italienne de Physique (SIF). Le Prof. Remo Ruffini, Directeur d'ICRANet, le Prof. Jorge Rueda, Professeur de la Faculté d'ICRANet et le Prof. Costantino Sigismondi, collaborateur ICRANet, ont été invite à participer et présenter leur conférence à travers une présentation vidéo qui portait sur leur derniers résultats scientifiques. le Prof. Ruffini a présenté son travail titré "Magnetic fields and afterglows of BdHNe: Inferences from GRB 130427A, GRB 160509A, GRB 160625B, GRB 180728A and GRB 190114C", le Prof. Rueda a présenté un travail titré "On the inner engine of the high-energy (GeV) emission of gamma-ray bursts", tandis que le Prof. Sigismondi, a présenté "L'éclipse de Betelgeuse", étoile rouge super géante d'Orion qui, entre-temps, a rejoint une magnitude visible de 0.65, un valeur qui pourra être proche à celui de la phase de maximum après le deuxième obscurcissement en l'espace de quelque mois.
Pour le site web de la conférence: https://www.sif.it/attivita/congresso/106

9. "Dante e l'Astronomia" podcast meeting, 13 Septembre 2020

C. Sigismondi, ICRA/Sapienza

La notoriété de Dante est internationale, tel qu'était le poète à ses temps. Traces de son passage restent toujours visible à l'Université de Paris. Ses pèlerinages, pour raisons politiques et professionnelles, peuvent être retrouvés dans la Divine Comédie. Sa poésie a été capable d'embrasser tous les aspects culturels, artistiques, théologiques ainsi que scientifiques et religieux de ses temps.
Le podcast meeting inauguré le 13 Septembre 2020 est expressément dédié à Dante et à l'Astronomie. Il a ouvert les célébrations centenaires pour la mort de Dante, qui s'est passé à Ravenne dans la nuit entre le 13 et le 14 Septembre 1321. Dante est une icône de la culture médiévale, qui unit science et foi.

Figure 3. Dante Alighieri (1265-1321).

"e nove Muse mi dimostran lOrse" (Par. II, 9)
c'est le verse choisi pour le titre de l'évent: 9 muses (toutes les arts), contribuant à montrer les Ursae, à maintenir le Nord, la direction correcte, dans le merveilleuse voyage que Dante était capable de faire (no Enée, un héro classique, no St. Paul Apôtre…comme il écrit). C'était pas simplement un Nord figurative, une boussole dans le difficile mer de la vie. Dante a montré différent imagines d'observation génuine de phénomènes physiques, et sa surprise face à des événements astronomiques qu'il a expérimenté il-même.
L'Astronomie comme une langue en code, les observations astronomiques remplies de sensations nostalgiques, corps astronomiques comme témoins silencieuses de les phases de la vie humaine, avant et après le passage de la mort, dont Dante est le chantre par excellence.
Dans ce meeting, consacré surtout aux jeunes étudiants et aux estimateurs de Dante, on a eu aussi des contributions par des scientifiques. Le podcast a été accueilli par l'ICRANet de Pescara et organisé en collaboration avec l'Observatoire astrophysique de Asiago et lAcadémie des Lynx. le patronage à la Commission III d'Histoire et astronomie du IAU a été aussi demandé.
Pour des information en plus sur le podcast: http://www.icranet.org/index.php?option=com_content&task=view&id=1334
Pour un communiqué de presse (en italien) par la chaîne de télévision régionale Rete 8: https://www.rete8.it/cronaca/icranet-dante-e-lasrtronomia/

10. Publications récentes

N. Sahakyan, D. Israyelyan, G. Harutyunyan, M. Khachatryan and S. Gasparyan, Multiwavelength Study of High-Redshift Blazars, accepted for publication in MNRAS.
High-redshift blazars are among the most powerful objects in the Universe. The spectral and temporal properties of thirty-three distant blazars (z > 2.5) detected in the high energy γ-ray band are investigated by analyzing the Fermi-LAT and Swift UVOT/ XRT data. The considered sources have soft time averaged γ-ray spectra (Γγ ≥ 2.2) whereas those that have been observed in the X-ray band have hard X-ray spectra (ΓX = 1.01 − 1.86). The γ-ray flux of high-redshift blazars ranges from 4.84 × 10−10 to 1.50 × 10−7 photon cm−2 s−1 and the luminosity is within (0.10 − 5.54) × 1048 erg s−1 which during the γ-ray flares increases up to (0.1 − 1) × 1050 erg s−1. In the X-ray band, only the emission of PKS 0438-43, B2 0743+25 and TXS 0222+185 is found to vary in different Swift XRT observations whereas in the γ-ray band, the emission is variable for fourteen sources: the flux of B3 1343+451 and PKS 0537-286 changes in sub-day scales, that of PKS 0347-211 and PKS 0451-28 in day scales, while the γ-ray variability of the others is in week or month scales. The properties of distant blazar jets are derived by modeling the multiwavelength spectral energy distributions within a one-zone leptonic scenario assuming that the X-ray and γ-ray emissions are produced from inverse Compton scattering of synchrotron and dusty torus photons. From the fitting, the emission region size is found to be ≤0.05 pc and the magnetic field and the Doppler factor are correspondingly within 0.10 − 1.74 G and 10.0 − 27.4. By modeling the optical-UV excess, we found that the central black hole masses and accretion disk luminosities are within Ld ≃ (1.09 − 10.94) × 1046 erg s−1 and (1.69 − 5.35) × 109 M, respectively.
DOI: https://doi.org/10.1093/mnras/staa2477
Link: https://ui.adsabs.harvard.edu/abs/2020arXiv200809675S/abstract

N. Sahakyan, G. Harutyunyan, D. Israyelyan and M. Khachatryan, Exploring the Origin of Multiwavelength Emission from High-Redshift Blazar B3 1343 + 451, published in Astrophysics, Volume 63, Issue 3, p.334-348, 2020.
B3 1343 + 451 is a distant ( z = 2.534 ) and bright flat-spectrum radio quasar observed in the γ -ray band. The results from the multiwavelength observations of B3 1343 + 451 with Fermi-LAT and Swift are reported. In the γ -ray band, strong flares were observed on 05 December 2011 and on 13 December 2009 when the flux increased up to (8.78 ± 0.83).10-7 photon cm-2 s-1. The hardest photon index Γ = 1.73 ± 0.24 has been observed on MJD 58089 which is not common for flat-spectrum radio quasars. The analysis of Swift XRT data shows that in 2014 the X-ray flux of the source increased ~2 times as compared to 2009, but in both periods the X-ray emission is characterized by a hard photon index of ΓX-ray = 1.2-1.3. During the γ -ray flares, the shortest flux halving timescale was ~2.34 days, implying the emission had been produced in a very compact region, R ≤ δ ct /(1 + z) = 3.43.1016 cm (when δ = 20). The spectral energy distribution of B3 1343 + 451 is modeled during the quiescent and flaring periods assuming a compact emitting region outside the BLR. It is found that the flares can be explained by only changing the bulk Lorentz factor of the emitting region without significant modification of the emitting electron parameters and luminosity of the jet.
DOI: https://doi.org/10.1007/s10511-020-09638-z
Link: https://ui.adsabs.harvard.edu/abs/2020Ap.....63..334S/abstract

MAGIC collaboration, Testing two-component models on very high-energy gamma-ray-emitting BL Lac objects, Astronomy & Astrophysics, Volume 640, id.A132, 29 pp., 2020.
Context. It has become evident that one-zone synchrotron self-Compton models are not always adequate for very high-energy (VHE) gamma-ray-emitting blazars. While two-component models perform better, they are difficult to constrain due to the large number of free parameters.
Aims: In this work, we make a first attempt at taking into account the observational constraints from very long baseline interferometry (VLBI) data, long-term light curves (radio, optical, and X-rays), and optical polarization to limit the parameter space for a two-component model and test whether or not it can still reproduce the observed spectral energy distribution (SED) of the blazars.
Methods: We selected five TeV BL Lac objects based on the availability of VHE gamma-ray and optical polarization data. We collected constraints for the jet parameters from VLBI observations. We evaluated the contributions of the two components to the optical flux by means of decomposition of long-term radio and optical light curves as well as modeling of the optical polarization variability of the objects. We selected eight epochs for these five objects based on the variability observed at VHE gamma rays, for which we constructed the SEDs that we then modeled with a two-component model.
Results: We found parameter sets which can reproduce the broadband SED of the sources in the framework of two-component models considering all available observational constraints from VLBI observations. Moreover, the constraints obtained from the long-term behavior of the sources in the lower energy bands could be used to determine the region where the emission in each band originates. Finally, we attempt to use optical polarization data to shed new light on the behavior of the two components in the optical band. Our observationally constrained two-component model allows explanation of the entire SED from radio to VHE with two co-located emission regions.
DOI: https://doi.org/10.1051/0004-6361/202037811
Link: https://ui.adsabs.harvard.edu/abs/2020A%26A...640A.132M/abstract

D. Maričić, B. Vršnak, A. M. Veronig, M. Dumbović, F. Šterc, D. Roša, M. Karlica, D. Hržina & I. Romštajn, Sun-to-Earth Observations and Characteristics of Isolated Earth-Impacting Interplanetary Coronal Mass Ejections During 2008-2014, published in Sol Phys 295, 91 (2020).
A sample of isolated Earth-impacting interplanetary coronal mass ejections (ICMEs) that occurred in the period January 2008 to August 2014 is analyzed to study in detail the ICME in situ signatures, with respect to the type of filament eruption related to the corresponding CME. Observations from different vantage points provided by the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory Ahead and Behind (STEREO-A and B) are used to determine whether each CME under study is Earth directed or not. For Earth-directed CMEs, a kinematical study was performed using the STEREO-A and B COR1 and COR2 coronagraphs and the Heliospheric Imagers (HI1), to estimate the CME arrival time at 1 AU and to link the CMEs with the corresponding in situ solar wind counterparts. Based on the extrapolated CME kinematics, we identified interacting CMEs, which were excluded from further analysis. Applying this approach, a set of 31 isolated Earth-impacting CMEs was unambiguously identified and related to the in situ measurements recorded by the Wind spacecraft. We classified the events into subsets with respect to the CME source location, as well as with respect to the type of the associated filament eruption. Hence, the events are divided into three subsamples: active region (AR) CMEs, disappearing filament (DSF) CMEs, and stealthy CMEs. The related three groups of ICMEs were further divided into two subsets: magnetic obstacle (MO) events (out of which four were stealthy), covering ICMEs that at least partly showed characteristics of flux ropes, and ejecta (EJ) events, not showing such characteristics. In this way, 14 MO-ICMEs and 17 EJ-ICMES were identified. The solar source regions of the non-stealthy MO-ICMEs are found to be located predominantly (9/10, 90%) within ±30∘±30∘ from the solar central meridian, whereas EJ-ICMEs originate predominantly (16/17, 94%) from source regions that are outside ±30∘±30∘. In the next step, MO-events were analyzed in more detail, considering the magnetic field strength and the plasma characteristics in three different segments, defined as the turbulent sheath (TS), the frontal region (FR), and the MO itself. The analysis revealed various well-defined correlations for AR, DSF, and stealthy ICMEs, which we interpreted considering basic physical concepts. Our results support the hypothesis that ICMEs show different signatures depending on the in situ spacecraft trajectory, in terms of apex versus flank hits.
DOI: https://doi.org/10.1007/s11207-020-01658-4
Link: https://link.springer.com/article/10.1007/s11207-020-01658-4
ICRANet Seats
Director and Staff
Personal Pages
Official Documents
Scientific Agreements
Annual reports
Upcoming Meetings
Marcel Grossmann
Galileo - Xu Guangqi
C. Lattes Meeting
Bego Scientific Rencontre
Zeldovich Meetings
Meetings in Armenia
Past meeting series
Single meetings
ICRANet Workshops
Other Meetings
IRAP Ph.D. Schools
Weekly Seminars
Research Groups
Press releases
Recorded talks
Public Events
Visitors: 196520075