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ICRANet Newsletter
August/September 2021





1. ICRA - ICRANet press release "Classifying Seyfert galaxies with deep learning"

Scientist uses deep learning to identify low luminous Seyfert 1.9 galaxies that are usually missed by human inspection among ten thousands of spectra. These results are published in the Astrophysical Journal Supplement Series on 28 September 2021 by a PhD student, Yen Chen Chen, in the department of physics at Sapienza University of Rome and the International Center for Relativistic Astrophysics Network (ICRANet).
Seyfert 1 and Seyfert 2 galaxies have distinct features on their spectra and the difference is explained by different viewing angles in the unification model of active galactic nuclei. However, a few Seyfert galaxies called intermediate Seyfert (Seyfert 1.2, 1.5, 1.8, 1.9) share spectral features from Seyfert 1 and Seyfert 2 and these two-component sources are hard to be explained by the unification model. At early time, these sources were picked out by vision inspection and hard to be picked out from amount observation data. Recently, astronomers usually fit candidate spectra to find these two-component sources. However, the fitting process usually spends a lot of time and the classification results are dependent on fitting results. Now, this classification process can be done by deep learning. Scientist builds a convolution neural network (CNN) model and feeds the model with a known sample of Seyfert 1.9 galaxies. The result shows that the trained CNN model has a high ability to recognize Seyfert 1.9 galaxies and the trained model finds new Seyfert 1.9 sources.


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

The novel point is that this method only needs a few known sources for training model and the training process is fast. Besides, the trained model can obtain more new sources in a faster way ever. This work shows a practical method in identifying sources and can be applied in the future. These new Seyfert 1.9 sources have obscure characteristic on its spectra and are usually missed in classification process by visual inspection. Scientist finds this machine-selected Seyfert 1.9 sample is fainter than the human selected one. This work provides astronomers more Seyfert 1.9 sources to low luminous end and will help astronomers understand the origin of the two components on its emission lines with multiple wavelength follow-up observation.

Link to the press release on INAF website: http://www.inaf.it/en/inaf-news/seyfert-galaxies-dl
Link to the press release on ICRANet website: http://www.icranet.org/communication/28092021/eng.pdf
Reference: Yen Chen Chen, Classifying Seyfert Galaxies with Deep Learning ApJS 256 34. https://iopscience.iop.org/article/10.3847/1538-4365/ac13aa



2. The 17th Italian- Korean Symposium (IK17), August 2 - 6, 2021

The Italian-Korean Symposia on Relativistic Astrophysics is a series of biannual meetings, alternatively organized in Italy and in Korea since 1987. The 17th Italian-Korean Symposium on Relativistic Astrophysics has been held from August 2 to 6, 2021 in a mixed format: in person at Kunsan National University (Gunsan, Korea) and online.


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.

The opening remarks have been presented by Prof. Byeong-Sun Kwak (President of the Kunsan National University), by H.E. Amb. Federico Failla (Ambassador of Italy in Korea) and by Prof. Remo Ruffini (Director of ICRANet and President of ICRA). During this five days conference, a variety of topics in astrophysics and cosmology were discussed, such as 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. The most recent scientific developments were presented by eminent Professors and researchers. The speakers for the Korean part were Prof. Sang Pyo Kim and Prof. Jin Young Kim (Kunsan National University), Prof. Stefano Scopel, Prof. Mu-In Park, Prof. Lu Yin, Prof. Eoin O Colgain, Prof. Wontae Kim, Prof. Wonwoo Lee and Prof. Hochoel Lee (Sogang University), Prof. Pisin Chen (National Taiwan University & Stanford University), Prof. Hyun Kyu Lee (Hanyang University), Prof. Dong-Hoon Kim (Seoul National University), Prof. Lang Liu (Institute of Theoretical Physics), Prof. Chen-Te Ma and Prof. Mahdis Ghodrati (APCTP), prof. Daniele Gregoris (Jiangsu University of Science and Technology), Prof. Bogeun Gwak (Dongguk University), Prof. Chan Park (NIMS), Prof. Chang-Hwan Lee and Prof. Dong-han Yeom (Pusan National University), Prof. Myeonghwan Oh (Kyungpook National University) and Prof. Sung-Won Kim (Ewha Womans University). The ICRANet speakers were Prof. Remo Ruffini, Prof. Jorge A. Rueda H., Prof. Narek Sahakyan, Prof. Soroush Shakeri, Prof. Shesheng Xue, Prof. Carlos Arguelles, Prof. Rahim Moradi, Prof. Liang Li, Prof. Maria Giovanna Dainotti and Prof. Kuantay Boshkayev.


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

The IK17 proceedings will collect all the presentations of the meeting, which will be published in the Journal of the Korean Physical Society (JKPS). The deadline for the submission is October 31, 2021.
For more information about the meeting, please see: http://45.120.69.181/plan.php/kis2021



3. 23 RAGtime meeting Opava, Czech Republic, September 6-10, 2021

From September 6 to 10, 2021, Professor Ruffini, Director of ICRANet, visited Silesian University in Opava (Czech Republic). Together with Prof. Jorge Rueda (ICRANet Faculty Professor), they have been invited to deliver 2 lectures on the occasion of the 23rd RAGtime meeting. Prof. Ruffini presented a lecture titled "Derivation of the existence of the Black Holic Quantum from GRBs" while Prof. Rueda presented a lecture titled "Quantifying the blackholic quantum in GRBs and AGN".


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.

For the video of Prof. Ruffini on ICRANet YouTube channel:
https://youtu.be/G9BEgdvJSVU
For the video of Prof. Rueda on ICRANet YouTube channel:
https://youtu.be/fUtBWlCFQvg



4. 107th SIF National Congress, September 13 - 17, 2021

From September 13 to 17, 2021, the Italian Physical Society (Società Italiana di Fisica, SIF) held its online 107th National Congress. Prof. Remo Ruffini (Director of ICRANet), Prof. Jorge Rueda (ICRANet Faculty Professor), Prof. Gregory Vereshchagin (ICRANet Faculty Professor), Prof. Rahim Moradi (ICRANet Faculty Professor) and Dr Stefano Campion, were invited to participate and present their talk through a video presentation reporting on their latest scientific results. Prof. Ruffini presented a talk titled "GRB 180720B: a BDHNI prototype", Prof. Rueda presented a talk titled "The long GRB afterglow from the radio to the X-rays in the binary-driven hypernova scenario", Prof. Vereshchagin presented a talk titled "Kinetic effects in nonequilibrium electron-positron plasmas", Prof. Moradi presented a talk titled "GRB-SNe connection within the binary-driven hypernova (BdHN) model" and Dr Campion presented a talk titled "Magnetic field screening in strong crossed electromagnetic fields".
For more information, please check the conference website: https://www.sif.it/attivita/congresso/107



5. Upcoming meeting: ICRANet - Isfahan Astronomy Meeting, Iran and online, November 3-5, 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 BiaƂystok), 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 (νpeak) 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 formula , 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 ee+ pairs.
DOI: https://doi.org/10.1016/j.physletb.2021.136562
 
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