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2021
February/March - April/May - June/July - August/September - October/November - December/January 2022

2022  -   2023

NGC 2992 (right) and NGC 2993 (left). Credit Line and Copyright Adam Block/ Mount Lemmon SkyCenter/University of Arizona.

Fig. 1: H.E. Amb. Federico Failla (Ambassador of Italy in Korea) on the occasion of the official opening ceremony of IK17 meeting, August 2, 2021.

Fig. 2: Prof. Remo Ruffini, Prof. Rahim Moradi and Prof. Soroush Shakeri presenting their lecture at the IK17 meeting.

Fig. 3: Prof. Remo Ruffini presenting his talk at the 23rd RAGtime meeting in Opava, September 7, 2021.

Fig. 4: Prof. Jorge Rueda presenting his talk at the 23rd RAGtime meeting in Opava, September 7, 2021.

It gives us great pleasure to announce the "ICRANet - Isfahan Astronomy Meeting. From the Ancient Persian Astronomy to Recent Developments in Theoretical and Experimental Physics, Astrophysics and General Relativity". Isfahan, as an historical city in the center of Iran and as one of the world's most beautiful cities, will host the first series of this meeting, which will be held from 3 to 5 November 2021 at the Isfahan University of Technology (IUT - Iran) and online.
This meeting, co organized by ICRANet and IUT, will provide a great opportunity for discussing about topics ranging from the ancient Persian astronomy to recent developments in observational astronomy, high energy astrophysical phenomena such as Gamma-Ray Bursts (GRBs) and Active Galactic Nuclei (AGNs), Theories of Gravity, General Relativity and its Mathematical Foundation, Black Holes, Dark matter and Early Universe Cosmology. A workshop on Data Science in Astrophysics will be also held during the meeting.
Members of the meeting Scientific Committee are the chair, Prof. Remo Ruffini (ICRANet/ICRA), the co-chair, Prof. Yousef Sobouti (ISABS, Iran), Prof. Hassan Firouzjahi (IPM, Iran), Prof. Shahram Khosravi (KHU, Iran), Prof. Habib Khosroshahi (IPM), Prof. Kourosh Nozari (UMZ, Iran), Prof. Sohrab Rahvar (SUT, Iran), Prof. Soroush Shakeri (IUT), Prof. Shadi Tahvildar-Zadeh (Rutgers, USA) and Prof. She-Sheng Xue (ICRANet). Members of the meeting Organizing Committee are the Chair, Prof. Soroush Shakeri (IUT), Prof. Amin Farhang (IPM and IUT), Prof. Fazlollah Hajkarim (UNIPD, Italy), Prof. Rahim Moradi (ICRANet), Prof. Sedigheh Sajadian (IUT), Prof. Shahab Shahidi (DU, Iran), Prof. Wang Yu (ICRANet) and Prof. M. H. Zhollideh Haghighi (IPM,KNTU, Iran).
The scientific program is in preparation, and more details about the event will be published on its webpage: https://indico.icranet.org/event/2/. We kindly encourage you to register to the meeting at the following link: https://indico.icranet.org/event/2/registrations/4/.
For more information about the ICRANet-Isfahan collaboration, please see: http://www.icranet.org/index.php?option=com_content&task=view&id=1059 - https://indico.icranet.org/event/2/page/9-icranet-isfahan.

6. Upcoming meeting: Damour Fest meeting, IHES Paris, October 12-15, 2021

It gives us great pleasure to announce the meeting "Damour Fest: Adventures in Gravitation", which will be held on October 12 - 15, 2021 at the Institut des Hautes Études Scientifiques (IHES, France) and online. The event will be held in a blended form, with talks given on site at IHES and others remotely through Zoom.
This conference, organized by Nathalie Deruelle (APC, Université de Paris), Alessandro Nagar (INFN Torino), and Slava Rychkov (IHES), would be a tribute on the occasion of the 70th anniversary of Prof. Thibault Damour. Prof. Damour is a permanent professor at IHES since 1989. He is a theoretical physicist specializing in general relativity and string theory. He is known worldwide for his innovative work on black holes, gravitational waves, and quantum cosmology. Throughout his career, he has received numerous international awards, such as the prestigious Einstein Medal and the CNRS Gold Medal, and more recently (in 2021) the Galileo Galilei Medal, the ICTP Dirac medal, and the Balzan Prize.
The confirmed invited speakers are: Prof. Leor Barack (University of Southampton), Prof. Sebastiano Bernuzzi (University of Jena), Prof. Lydia Bieri (Michigan University), Prof. Luc Blanchet (IAP, Paris), Prof. Alessandra Buonanno (AEI, MPI, Potsdam), Prof. Sophie De Buyl (Vrije Universiteit Brussel), Prof. Stanley Deser (Brandeis University), Prof. Marc Henneaux (Collège de France & ULB Bruxelles), Prof. Bala Iyer (ICTS, Tata institute, Bangalore), Prof. Piotr Jaranowski (University of Białystok), Prof. Sergiu Klainerman (Princeton University), Prof. Michael Kramer (MPI, Bonn), Prof. Juan Maldacena (IAS, Princeton), Prof. Viatcheslav Mukhanov (Ludwig Maximilian University, Munich), Prof. Hermann Nicolai (AEI, MPI, Potsdam), Prof. Adam Pound (University of Southampton), Prof. Giuseppe Policastro (ENS Paris), Prof. Alexander Polyakov (Princeton University), Prof. Manuel Rodrigues (ONERA, Université Paris-Saclay), Prof. Remo Ruffini (ICRA, ICRANet), Prof. David Shoemaker (MIT), Prof. Sergey Solodukhin (University of Tours), Prof. Alexei Starobinski (Landau Institute, Moscow), Prof. Gabriele Veneziano (CERN & Collège de France), Prof. Alex Vilenkin (Tufts University) and Prof. Edward Witten (IAS, Princeton).
The programme is in preparation and will be available on the conference website at the following link: https://indico.math.cnrs.fr/event/6802/
We kindly encourage you to register to the meeting at the following link: https://indico.math.cnrs.fr/event/6802/registrations/557/
For more information, please contact Elisabeth Jasserand, the IHES scientific activities coordinator: jasserand@ihes.fr (email), +33 (0)160926604 (phone).

7. Seminar of Prof. Ivan Rybak at ICRANet center, September 22, 2021

On Wednesday, September 22, 2021, Dr. Ivan Rybak (Centro de Astrofísica da Universidade do Porto - Portugal) presented a seminar titled "Cosmic (super/superconducting) strings as a probe of high energy physics" with the following abstract:
The theoretical possibility of cosmic strings existence was suggested in the 1970s. Since that time, these hypothetical objects have passed through the ups and downs of scientific community attention. Cosmic strings evoked particular interest in the 2000s, whereby implementing superstring theory to the early universe description, we "have discovered cosmic strings lurking everywhere in the undergrowth", as was expressed by Tom Kibble. Nowadays, many scenarios that extend the Standard Model of particles physics suggest the production of cosmic string. Future missions, such as LISA, with improved observational facilities, will probe models where cosmic strings occur, thereby shedding light on possible early universe scenarios. In this talk, I will make a short overview of models where cosmic strings take place. I will provide state of the art methods to study the evolution of cosmic strings and explain why we should pay attention to cosmic superconducting and (super)strings. I will conclude with current and future observational constraints on cosmic strings.
The announcement of the seminar has also been published on ICRANet website: http://www.icranet.org/index.php?option=com_content&task=blogcategory&id=89&Itemid=781
The video of the seminar is available on ICRANet YouTube channel at the following link: https://youtu.be/sZr1LKzDIvw

Fig. 5 and 6: Dr Ivan Rybak giving his seminar at ICRANet center in Pescara, September 22, 2021.

8. Visit of Prof. Vladimír Karas, Director of the Astronomical Institute of the Czech Academy of Sciences, at ICRA Seat, Rome, September 27, 2021

On September 27, 2021, Prof. Vladimír Karas, Director of the Astronomical Institute of the Czech Academy of Sciences, came to Italy and visited the ICRA Seat in Sapienza University of Rome. On that occasion, he had the possibility to visit the Seat and to sign the ICRA wall, as previously done by eminent scientists and Nobel laureates who collaborated with ICRA and gave their significant support to its activities. On that occasion, Prof. Ruffini discussed many scientific issues with Prof. Karas and had also the possibility to propose him a possible collaboration agreement between ICRANet and his center in Prague.

Fig. 7: Prof. Vladimír Karas, Director of the Astronomical Institute of the Czech Academy of Sciences, signing ICRA wall at the Sapienza University of Rome, September 27, 2021.	Fig. 8: ICRA wall at Sapienza University of Rome.

9. Scientific visits to ICRANet

	• Dr. Ivan Rybak (Centro de Astrofísica da Universidade do Porto - Portugal), September 22-23, 2021
	• Prof. Narek Sahakyan (Director of ICRANet Armenia), September 24 - 25, 2021

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.

10. Recent publications

Yen Chen Chen, Classifying Seyfert Galaxies with Deep Learning ApJS 256 34. The traditional classification for a subclass of the Seyfert galaxies is visual inspection or using a quantity defined as a flux ratio between the Balmer line and forbidden line. One algorithm of deep learning is the convolution neural network (CNN), which has shown successful classification results. We build a one-dimensional CNN model to distinguish Seyfert 1.9 spectra from Seyfert 2 galaxies. We find that our model can recognize Seyfert 1.9 and Seyfert 2 spectra with an accuracy of over 80% and pick out an additional Seyfert 1.9 sample that was missed by visual inspection. We use the new Seyfert 1.9 sample to improve the performance of our model and obtain a 91% precision of Seyfert 1.9. These results indicate that our model can pick out Seyfert 1.9 spectra among Seyfert 2 spectra. We decompose the Hα emission line of our Seyfert 1.9 galaxies by fitting two Gaussian components and derive the line width and flux. We find that the velocity distribution of the broad Hα component of the new Seyfert 1.9 sample has an extending tail toward the higher end, and the luminosity of the new Seyfert 1.9 sample is slightly weaker than the original Seyfert 1.9 sample. This result indicates that our model can pick out the sources that have a relatively weak broad Hα component. In addition, we check the distributions of the host galaxy morphology of our Seyfert 1.9 samples and find that the distribution of the host galaxy morphology is dominated by a large bulge galaxy. In the end, we present an online catalog of 1297 Seyfert 1.9 galaxies with measurements of the Hα emission line.
DOI: 10.3847/1538-4365/ac13aa


Giommi P., Perri M., Capalbi M., D'Elia V., Barres de Almeida U., Brandt C.H., Pollock A.M.T., et al., X-ray spectra, light curves and SEDs of blazars frequently observed by Swift, MNRAS, Volume 507, Issue 4, November 2021, Pages 5690-5702.
Blazars research is one of the hot topics of contemporary extragalactic astrophysics. That is because these sources are the most abundant type of extragalactic γ-ray sources and are suspected to play a central role in multimessenger astrophysics. We have used Swift_xrtproc, a tool to carry out an accurate spectral and photometric analysis of the Swift-XRT data of all blazars observed by Swift at least 50 times between December 2004 and the end of 2020. We present a database of X-ray spectra, best-fit parameter values, count rates and flux estimations in several energy bands of over 31 000 X-ray observations and single snapshots of 65 blazars. The results of the X-ray analysis have been combined with other multifrequency archival data to assemble the broad-band Spectral Energy Distributions (SEDs) and the long-term light curves of all sources in the sample. Our study shows that large X-ray luminosity variability on different time-scales is present in all objects. Spectral changes are also frequently observed with a ‘harder-when-brighter’ or ‘softer-when-brighter’ behaviour depending on the SED type of the blazars. The peak energy of the synchrotron component (ν_peak) in the SED of HBL blazars, estimated from the log-parabolic shape of their X-ray spectra, also exhibits very large changes in the same source, spanning a range of over two orders of magnitude in Mrk421 and Mrk501, the objects with the best data sets in our sample.
DOI: https://doi.org/10.1093/mnras/stab2425


Fraga B.M.O., Barres de Almeida U., Bom C.R., Brandt C.H., Giommi P., Schubert P., de Albuquerque M.P., Deep learning Blazar classification based on multifrequency spectral energy distribution data, MNRAS, Volume 505, Issue 1, July 2021, Pages 1268-1279.
Blazars are among the most studied sources in high-energy astrophysics as they form the largest fraction of extragalactic gamma-ray sources and are considered prime candidates for being the counterparts of high-energy astrophysical neutrinos. Their reliable identification amid the many faint radio sources is a crucial step for multimessenger counterpart associations. As the astronomical community prepares for the coming of a number of new facilities able to survey the non-thermal sky at unprecedented depths, from radio to gamma-rays, machine-learning techniques for fast and reliable source identification are ever more relevant. The purpose of this work was to develop a deep learning architecture to identify Blazar within a population of active galactic nucleus (AGN) based solely on non-contemporaneous spectral energy distribution information, collected from publicly available multifrequency catalogues. This study uses an unprecedented amount of data, with spectral energy distributions (SEDs) for ≈14 000 sources collected with the Open Universe VOU-Blazars tool. It uses a convolutional long short-term memory neural network purposefully built for the problem of SED classification, which we describe in detail and validate. The network was able to distinguish Blazars from other types of active galactic nuclei (AGNs) to a satisfying degree (achieving a receiver operating characteristic area under curve of 0.98), even when trained on a reduced subset of the whole sample. This initial study does not attempt to classify Blazars among their different sub-classes, or quantify the likelihood of any multifrequency or multimessenger association, but is presented as a step towards these more practically oriented applications.
DOI: https://doi.org/10.1093/mnras/stab1349


S. Campion, J.A. Rueda, R. Ruffini, S.S. Xue, Magnetic field screening in strong crossed electromagnetic fields, Physics Letters B, Volume 820, 10 September 2021, 136562.
We consider crossed electric and a magnetic fields , with E/B <1, in presence of some initial number of e^± pairs. We do not discuss here the mechanism of generation of these initial pairs. The electric field accelerates the pairs to high-energies thereby radiating high-energy synchrotron photons. These photons interact with the magnetic field via magnetic pair production process (MPP), i.e. γ+B→e⁺+e⁻, producing additional pairs. We here show that the motion of all the pairs around the magnetic field lines generates a current that induces a magnetic field that shields the initial one. For instance, for an initial number of pairs N_±,0=10¹⁰, an initial magnetic field of 10¹²G can be reduced of a few percent. The screening occurs in the short timescales 10⁻²¹ ≤ t ≤ 10−¹⁵s, i.e. before the particle acceleration timescale equals the synchrotron cooling timescale. The present simplified model indicates the physical conditions leading to the screening of strong magnetic fields. To assess the occurrence of this phenomenon in specific astrophysical sources, e.g. pulsars or gamma-ray bursts, the model can be extended to evaluate different geometries of the electric and magnetic fields, quantum effects in overcritical fields, and specific mechanisms for the production, distribution, and multiplicity of the e⁻e⁺ pairs.
DOI: https://doi.org/10.1016/j.physletb.2021.136562