ICRANet Newsletter

Bulletin ICRANet
Avril - Mai 2019

English - French - Italian - Portuguese

RÉSUMÉ
1. L'ICRANet a reçu un prix pour on article dans le cadre de la Gravity Research Foundation Award Competition 2019
2. Renouvellement de l'accord de collaboration entre ICRANet et UFRGS, 5 Avril, 2019
3. Journée de la Science italo-arménienne, Erevan, 15 Avril 2019
4. Communiqué de presse ICRANet "Le Professeur Roy Kerr élu membre de la Royal Society", 18 Avril 2019
5. Visite d'étudiants Erasmus du Lycée ITIS Alessandro Volta, 7 Mai 2019
6. Mission du Professeur Ruffini en Chine, 10 – 22 Mai 2019
7. Conférences à venir
8. Publications récentes

1. L'ICRANet a reçu un prix pour on article dans le cadre de la Gravity Research Foundation Award Competition 2019

The article "Can Fermionic Dark Matter Mimic Supermassive Black Holes?" by C. R. Argüelles, A. Krut, J. A. Rueda and R. Ruffini receives the Third Award by the Gravity Research Foundation www.gravityresearchfoundation.org in the Award Competition 2019. The paper analyzes the intriguing possibility to explain both dark mass components in a galaxy: the dark matter (DM) halo and the supermassive dark compact object lying at the center, by a unified approach in terms of a quasi-relaxed system of massive, neutral fermions in general relativity. The solutions to the mass distribution of such a model that fulfill realistic halo boundary conditions inferred from observations, develop a highly-density core supported by the fermion degeneracy pressure able to mimic massive black holes at the center of galaxies. Remarkably, these dense core-dilutedhaloconfigurations can explain the dynamics of the closest stars around Milky Way's center (SgrA*) all the way to the halo rotation curve, without spoiling the baryonic bulge-disk components, for a narrow particle mass range mc² ∼10-10² keV.
The paper can be downloaded here: https://arxiv.org/abs/1905.09776
For details see: https://www.gravityresearchfoundation.org/s/2019abstracts.pdf

2. Renouvellement de l'accord de collaboration entre ICRANet et UFRGS, 5 Avril, 2019

Le 5 Avril 2019, l'Accord de collaboration entre ICRANet et UFRGS (Universidade Federal do Rio Grande do Sul) a été renouvelé. Ce nouveau accord a été signé par le Prof. Dr. Rui Vincente Oppermann (Recteur de l'UFRGS), par la Prof. Naira Maria Balzaretti (Directrice du Département de Physique de l'UFRGS), par le Prof. Dr. Dimiter Hadjimichef (Département de Physique de l'UFRGS) et par le Prof. Remo Ruffini (Directeur of ICRANet).
Cet accord demeurera valid pour 5 années et les principales activités conjointes qui seront développées dans le cadre de cet accord comptent: la promotion des activités de recherche et d'observation dans le champ de l'astrophysique relativiste; la collaboration entre des membres de la Faculté, des chercheurs, des post-doctorat fellows et des étudiants; l'organisation de séminaires, conférences, workshops, cours de formations et de recherche, et publications conjointes.
Pour le texte de l'accord: http://www.icranet.org/index.php?option=com_content&task=view&id=842.

3. Journée de la Science italo-arménienne, Erevan, 15 Avril 2019

Le 15 Avril 2019, l'ICRANet a organisé la Journée de la Science italo-arménienne "Joint ICRANet activities in Relativistic Astrophysics. Information Event for Cooperation in the field of Relativistic Astrophysics", une conférence d'un jour qui a eu lieu a Erevan. Cet événement a été organisé grâce à la collaboration entre l'ICRANet, l'Académie Nationale des Sciences d'Arménie (NASRA) et l'Ambassade d'Italie à Erevan. la session matinale a eu lieu auprès de l'Académie Nationale des Sciences d'Arménie, alors que la session de l'après-midi s'est tenue auprès de l'Ambassade d'Italie à Erevan.


Des représentants institutionnels d'Arménie et de plusieurs d'autres pays ont pris partie et adressé la session matinal, notamment l'Ambassadeur Ashot Kocharian (Ministère des Affaires étrangers de la République d'Arménie), Artak Apitonian (Sous-ministre des Affaires étrangers de la République d'Arménie), Radik Martirosyan (Président de la NASRA), Samvel Haroutiunian (Président du comité de la science RA MES), Vardan Sahakyan (Vice-président du comité de la science RA MES), Vincenzo Del Monaco (Ambassadeur de l'Italie en Arménie), Matthias Kiesler (Ambassadeur de l'Allemagne en Arménie) et Remo Ruffini (Directeur d'ICRANet).
Pendant la journée, les plus récents développements scientifiques sur lesquels ICRANet est en train de travailler, ont été présentés par éminents Professeurs et chercheurs, notamment le Prof. Narek Sahakyan (ICRANet Arménie), Prof. Razmik Mirzoyan (Max Planck Institute of Physics, Allemagne), Dr Wang Yu (ICRANet), Rahim Moradi (ICRANet), Prof. Remo Ruffini (ICRANet), Dr Li Liang (ICRANet), Prof. Gregory Vereshchagin – vidéo conférence (ICRANet), Prof. Paolo Giommi (ICRANet-ASI), Ashot Chilingaryan (Cosmic Ray Division) et Leonid Bezrukov (vice-directeur de l'Institute pour la recherche nucléaire à Moscou).
Dans le même après-midi, le Professeur Remo Ruffini (Directeur d'ICRANet), a rencontré le Président de la République arménienne, S.E. Armen Sarkissian dans sa résidence à Erevan, à la tête d'une délégation ICRANet composée par l'Ambassadeur Ashot Kocharian, le Président Radik Martirosyan, le Prof. Narek Sahakyan, le Prof. Razmik Mirzoyan, le Prof. Paolo Giommi et le Prof. Massimo Della Valle. Le Président Sarkissian a remarqué l'importance des activités d'ICRANet en Arménie, en promouvant un fort développement de l'éducation et de la science dans le pays. Le Prof. Ruffini a souligné luimême la coopération avec l'Arménie et a l'intention d'implementer des nouveaux programs avec les pays de l'Asie centrale Asie via Arménie. Tous les interlocuteurs ont aussi discuté des possibilités d'implementer des 3programs conjoints et de renforcer la coopération avec les principaux centres mondiaux et universités, tel qu'ICRANet.


La Journée de la Science italo-arménienne a terminé avec le concert "Primavera Italiana", qui s'est tenu au Komitas Chamber Music Hall d'Erevan et a été offert par l'Ambassade italienne. Le concert a honoré plusieurs compositeurs d'opéra italiens, tels qu'Arcangelo Corelli, Giovanni Pergolesi, Antonio Vivaldi et Niccolò Paganini.

Pour plus de renseignements sur l'événement:
http://www.icranet.org/Armenian-ItalianScienceDay
Pour photos et vidéos:
http://www.icranet.org/index.php?option=com_content&task=view&id=1240
Pour les communiqués de presse sur cet événement:
http://www.icranet.org/index.php?option=com_content&task=view&id=1239

4. Communiqué de presse ICRANet "Le Professeur Roy Kerr élu membre de la Royal Society", 18 Avril 2019

Le Professeur néo-zélandais Roy Kerr, mathématicien et physicien, titulaire de la Yevgeny Lifshitz Chair d'ICRANet et Prix Crafoord pour l'Astronomie en 2016 pour "son travail fondamental sur les trous noirs rotant et leur conséquences astrophysiques", a été nommé membre de la Royal Society (UK) pour son exceptionnel contribution à la science. Cette nomination le pose entre les scientifiques les plus éminents au monde. Il sera officiellement nommé au cours d'une cérémonie d'admission, qui se tiendra le 12 Juillet 2019 à Londres.

La Royal Society a décerné le Professeur Kerr de ce prestigieux titre "pour la solution aux équations d'Einstein de la Relativité Générale pour les trous noirs rotant, un résultat historique reconnu comme Kerr metric, qui décrit les trous noirs de Kerr. Ses autres majeures contributions incluent son prescient work on algebraically special solutions of reduced holonomy."

En effet, le Prof. Roy Kerr découvrit en 1963 une solution exacte aux équations de la relativité générale de Albert Einstein: "Cette solution mathématique – rappelle le Prof. Remo Ruffini, Directeur d'ICRANet – a permis des progrès sans précédents dans l'application aux domaines de la physique, de l'astronomie et de l'astrophysique relativiste: l'application s'est étendu aussi au domaine de la microphysique des particules élémentaires, tels que la structure de l'électron, l'astrophysique des trous noirs qui se produise à la fin de l'évolution des étoiles, jusqu'aux procès les plus énergétiques de l'univers tel que les SRGs and les galaxies actives (NAG), où les trous noirs et les maxi trous noirs (des milliards de fois plus grand du soleil) dominent." C'était en effet Remo Ruffini avec John Archibald Wheeler à utiliser la solution mathématique de Kerr, en l'introduisant dans la description des procès physiques fondamentales, et en lui donnant le nom de "Trous Noir", qui a été traduit dans toutes les langues du monde (Physics Today, 30, 1971). Ces sujets ont été approfondis par Blandford et Znajek (MNRAS, 179, 433, 1977) à la suite d'un article par Ruffini et Wilson (Phys. Rev. D 12, 2959,1975).

La découverte de Kerr déclencha une révolution en physique et, depuis lors, son travail s'est avéré de grande importance et tous les travaux suivants sur les trous noirs en ont dépendu.

En 2006, le Prof. Roy Kerr a reçu le Marcel Grossmann Award à l'occasion du meeting international en Astrophysique Relativiste, qui a lieu chaque 3 années dans un pays différent. Le Prof. Roy Kerr a été Professeur de l'ICRANet dans le cadre du programme de doctorat IRAP PhD, le premier program de doctorat international conjoint, fondé par ICRANet et coordonné au niveau international par l'Université de Nice "Sophia Antipolis".

Le Professeur Kerr a été aussi important dans ces mois après que des astronomes ont capture la première image d'un trous noir.

5. Visite d'étudiants Erasmus du Lycée ITIS Alessandro Volta, 7 Mai 2019

Le 7 Mai 2019, une délégation d'étudiants Erasmus et des étudiants italiens du Lycée ITIS Alessandro Volta de Pescara, ont visité le centre ICRANet de Pescara. Sous la supervision de Gregory Vereshchagin, Professeur de la Faculté ICRANet, les étudiants ont eu la possibilité de visiter le centre et sa bibliothèque et ça a été pour eux une opportunité unique pour prendre partie aux activités scientifiques visant à présenter soit le charme de la recherche en tant que métier, soit son impact social significatif.
Après le discours d'ouverture du Professeur Vereshchagin, le Prof. She-Sheng Xue (ICRANet), le Dr Wang Yu (ICRANet), le Dr Liang Li (ICRANet), Rahim Moradi (ICRANet) et Yen-Chen Chen (ICRANet) ont présenté les plus récents développements scientifiques sur lesquels l'ICRANet est en train de travailler.

6. Mission du Professeur Ruffini en Chine, 10 – 22 Mai 2019

Du 11 au 18 Mai 2019, le Professeur Ruffini a visité la Chine, avec le Dr Yu Wang et le Dr Li Liang. Pendant sa visite, ils ont été invite à participer et donner une présentation dans le cadre de la conférence "Gamma-Ray Bursts and Related Astrophysics in Multi-Messenger Era", qui a eu lieu à l'Université de Nanjing du 13 au 17 Mai 2019.



Le Professor Ruffini a donné une présentation titré "Self-similar structure of the ultra-relativistic prompt emission of GRB 190114C", Dr Wang Yu titré "GRB 190114C: most comprehensive portrait of gamma-ray burst" et Dr Liang Li titré "Shock breakout in BdHN I and BdHN II, the case of GRB 13027A, 180728A and 190114C".



Pendant sa mission, le Prof. Ruffini a aussi rendu visite à des chercheurs chinois à l'Université Jiao-tong de Shanghai et a été invité par le Prof Shing-Tung Yau, Directeur du Yau Mathematical Science Center à visiter l'Université Tsinghua de Pékin, une de plus importantes Universités chinoises. Dans cette occasion, le Prof. Ruffini a eu un important rencontre avec le Prof. Yau et le Prof. Shude Mao, Directeur du Département d'astronomie de l'Université Tsinghua. Ensuite, le Prof. Ruffini s'est rendu à Hefei pour rencontrer le Prof. Ye-Fei Yuan du Département d'astronomie de l'Université de sciences et technologie de Chine (USTC).



Pendant sa visite, le Prof. Ruffini a eu aussi la posisbilité de presenter les plus récents developpements scientifiques sur lesquels ICRANet est en train de travailler, mais également d'avoir des fructueuses discussions avec des chercheurs de toutes les parties du monde.

Le vendredi 17 Mai 2019, le Prof. Remo Ruffini a envoyé un important message de la Chine, à l'occasion du 40^ème anniversaire de sa première visite en Chine:

"When I introduced in Princeton the concept of "Black Hole" with John Archibald Wheeler, our omen was to open a new era thanks to the study of Relativistic Astrophysics. Daily phone conversations between me (who was in Princeton) and Riccardo Giacconi (who was in Harvard), tying to interpret data from the satellite UHURU ("freedom" in Swahili, launched by Luigi Broglio from the space station San Marco in Kenia), made this omen a reality. In 1973, I received the Cressy Morrison Award from the New York Academy of Sciences for the discovery of the first "Black Hole" in the galaxy and, in 2002, Riccardo Giacconi received the Nobel Prize in Physics.
This progresses have also been marked in 1973 by another event destined to become memorable: the discovery of Gamma Ray Bursts (GRBs). To achieve their understanding/comprehension, it took more than 40 years marked by everyday theoretical studies, accompanied by a "multimessanger" technological and optical development without precedent in the history of humanity. Recently, there have been announcements of a Black Hole at the center of the galaxy, of binary Black Holes, a photo of a Black Hole with enormous multi-media clamor: very interesting if true, using an euphemism by Wigner.
Thanks to GRB 190114C observed on January 14, 2019, we have identified for the first time, the birth/origin of a "Black Hole", which manifested its existence through the emission of the biggest energy source in the Universe. A "new" energy source, 1030 bigger than the one of the atomic bomb of Los Alamos, with a particle flux 1042 and energies 1012 bigger than those of CERN and those planned in China at the CEPC. Fermi led the way: with his research in nuclear physics begun a new age economic, political and military development. Those who will control the science and technology based on this new enormous cosmic energy source, will decide the economic, political and military future of the planet".

7. Conférences à venir

Ecole doctorale internationale Open Universe, 10 - 14 Juin 2019

C'est notre plaisir d'annoncer l'Ecole doctorale internationale Open Universe "How the discovery of a Black Hole in GRB 190114C and in M87 is modifying the human outlook from planet Earth", une conference de 3 jours qui se tiendra du 11 au 14 Juin 2019 au siège ICRANet à Villa Ratti (Nice - France). Ce meeting est organisé grace à la collaboration entre l'ICRANet, le LAPP (Laboratoire d'Annecy de Physique des particules) et le Max Planck Institute for Physics. Le programme scientifique est en elaboration et des information en plus seront publiés, dès que disponibles, sur notre page web http://www.icranet.org/index.php?option=com_content&task=view&id=1241

16^ème rencontre Italo-coréen sur l'Astrophysique Relativiste

C'est notre plaisir d'annoncer le 16^ème rencontre Italo-coréen sur l'Astrophysique Relativiste, qui se tiendra auprès du centre ICRANet de Pescara du 1 au 5 Juillet 2019. Les rencontres Italo-coréens sur l'Astrophysique Relativiste sont une série de conférences biennales organisées depuis 1987 alternativement en Italie et en Corée. Les symposiums traitent de questions d'astrophysique et cosmologie, telles que les rayons gamma et les étoiles compactes, les rayons cosmiques de haute énergie, l'énergie obscure et la matière noire, la relativité générale, les trous noirs et la nouvelle physique liée à la cosmologie. Le programme est encore en cours de préparation et des informations en plus concernent la conférence seront publiées sur notre page web: http://www.icranet.org/index.php?option=com_content&task=view&id=1234

8. Publications récentes

Glauch, Theo; Padovani, Paolo; Giommi, Paolo; Resconi, Elisa; Arsioli, Bruno; Sahakyan, Narek; Huber, Matthias, Dissecting the region around IceCube-170922A: the blazar TXS 0506+056 as the first cosmic neutrino source, published online on Mai 10, 2019 in EPJ Web of Conferences 207, 02003 (2019).
On MJD 58018 the IceCube neutrino observatory detected a highlyenergetic, well-reconstructed neutrino, IceCube-170922A, at a distance of 0:1° to a γ-ray flaring blazar, TXS 0506+056. Follow-up searches in archival data additionally revealed a larger flare of neutrinos from the same direction. In order to complete the picture we present here a full multi-wavelength study of the region around IceCube-170922A. While we identify also other non-thermal counterpart candidates, we show that all the evidence points to TXS 0506+056 as the dominant neutrino emitter. Additionally, an analysis of all the available Fermi-LAT data indicates a hard spectrum/low flux of TXS 0506+056 during the neutrino flare in contrast to a soft spectrum/high flux at the arrival time of IceCube-170922A. Putting all the pieces together we conclude that the SED of TXS 0506+056 can be energetically reconnected for both neutrino observations.
Link:
https://www.epj-conferences.org/articles/epjconf/abs/2019/12/epjconf_vlvnt2018_02003/epjconf_vlvnt2018_02003.html


V. A. Acciari, S. Ansoldi, L.A. Antonelli, A. Arbet Engels, D. Baack, A. Babić, B. Banerjee, U. Barres de Almeida, J. A. Barrio, J. Becerra González, W. Bednarek, L. Bellizzi, E. Bernardini, A. Berti, J. Besenrieder, W. Bhattacharyya, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, G. Busetto, R. Carosi, G. Ceribella, Y. Chai, S. Cikota, S. M. Colak, U. Colin, E. Colombo, J.L. Contreras, J. Cortina, S. Covino, V. D'Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, F. Di Pierro, E. Do Souto Espiñeira, A. Domínguez, D. Dominis Prester, D. Dorner, M. Doro, D. Elsaesser, V. Fallah Ramazani, A. Fattorini, A. Fernández-Barral, G. Ferrara, D. Fidalgo, L. Foffano, M. V. Fonseca, L. Font, C. Fruck, D. Galindo, S. Gallozzi, R. J. García López, M. Garczarczyk, S. Gasparyan, M. Gaug, N. Godinović, D. Green, D. Guberman, D. Hadasch, A. Hahn, T. Hassan, J. Herrera, J. Hoang, D. Hrupec, S. Inoue, K. Ishio, Y. Iwamura, H. Kubo, J. Kushida, A. Lamastra, D. Lelas, F. Leone, E. Lindfors, S. Lombardi, F. Longo, M. López, R. López-Coto, A. López-Oramas, B. Machado de Oliveira Fraga, C. Maggio, P. Majumdar, M. Makariev, M. Mallamaci, G. Maneva, M. Manganaro, K. Mannheim, L. Maraschi, M. Mariotti, M. Martínez, S. Masuda, D. Mazin, S. Mićanović, D. Miceli, M. Minev, J. M. Miranda, R. Mirzoyan, E Molina, A. Moralejo, D. Morcuende, V. Moreno, E. Moretti, P. Munar-Adrover, V. Neustroev, A. Niedzwiecki, M. Nievas Rosillo, C. Nigro, K. Nilsson, D. Ninci, K. Nishijima, K. Noda, L. Nogués, M. Nöthe, S. Paiano, J. Palacio, M. Palatiello, D. Paneque, R. Paoletti, J. M. Paredes, P. Peñil, M. Peresano, M. Persic, P. G. Prada Moroni, E. Prandini, I. Puljak, W. Rhode, M. Ribó, J. Rico, C. Righi, A. Rugliancich, L. Saha, N. Sahakyan, T. Saito, K. Satalecka, T. Schweizer, J. Sitarek, I. Šnidarić, D. Sobczynska, A. Somero, A. Stamerra, D. Strom, M. Strzys, T. Surić, F. Tavecchio, P. Temnikov, T. Terzić, M. Teshima, N. Torres-Albà, S. Tsujimoto, J. van Scherpenberg, G. Vanzo, M. Vázquez Acosta, I. Vovk, M. Will, D. Zarić, Measurement of the extragalactic background light using MAGIC and Fermi-LAT gamma-ray observations of blazars up to z = 1, published on 4 April 2019 on Monthly Notices of the Royal Astronomical Society, Volume 486, Issue 3, July 2019, Pages 4233–4251.
We present a measurement of the extragalactic background light (EBL) based on a joint likelihood analysis of 32 gamma-ray spectra for 12 blazars in the redshift range z = 0.03–0.944, obtained by the MAGIC telescopes and Fermi-LAT. The EBL is the part of the diffuse extragalactic radiation spanning the ultraviolet, visible, and infrared bands. Major contributors to the EBL are the light emitted by stars through the history of the Universe, and the fraction of it that was absorbed by dust in galaxies and re-emitted at longer wavelengths. The EBL can be studied indirectly through its effect on very high energy photons that are emitted by cosmic sources and absorbed via γγ interactions during their propagation across cosmological distances. We obtain estimates of the EBL density in good agreement with state-of-the-art models of the EBL production and evolution. The 1σ upper bounds, including systematic uncertainties, are between 13 per cent and 23 per cent above the nominal EBL density in the models. No anomaly in the expected transparency of the Universe to gamma-rays is observed in any range of optical depth. We also perform a wavelength-resolved EBL determination, which results in a hint of an excess of EBL in the 0.18–0.62 μmμm range relative to the studied models, yet compatible with them within systematic.
Link: https://doi.org/10.1093/mnras/stz943


Gallego Cadavid, Alexander; Romano, Antonio Enea, One spectrum to rule them all?, to be published on Physics Letters B, Volume 793, p. 1-7 on June 2019.
We show that in absence of entropy or effective anisotropic stress the freedom in the choice of the initial energy scale of inflation implies the existence of an infinite family of dual slow-roll parameters histories which can produce the same spectrum of comoving curvature perturbations. This implies that in general there is no one-to-one correspondence between the spectrum and higher order correlation functions. We give some numerical examples of expansion histories corresponding to different initial energy scales, with the same spectrum of curvature perturbations, the same squeezed limit bispectrum, in agreement with the squeezed limit consistency condition, but with different bispectra in other configurations and different spectra of primordial gravitational waves. The combined analysis of data from future CMB and gravitational wave experiments could allow to distinguish between dual models.
Link:
https://www.sciencedirect.com/science/article/pii/S0370269319302497?via%3Dihub


Yen-Chen Chen, Chorng-Yuan Hwang, Emission line luminosity distributions of Seyfert 2 galaxies, published on March 8, 2019 on Monthly Notices of the Royal Astronomical Society, Volume 485, Issue 3, May 2019, Pages 3402–3408.
We probed the relation between line activities of Seyfert 2 galaxies and their host galaxies. We selected Seyfert 2 galaxies from the Sloan Digital Sky Survey Data Release 10 with redshifts less than 0.2. We used the luminosity of the emission lines as indicators of AGN power. We found that the Seyfert 2 galaxies seem to have two populations in the emission line luminosity distributions. We considered the L_[OIII]/L_bulge ratio as an accretion rate indicator and found that the two Seyfert 2 distributions seem to have different accretion rates. We found that these two Seyfert 2 populations, although classified by their emission line distributions, turned out to have different morphology distributions. These results indicate that these different populations of the Seyfert 2 galaxies might be significantly different in their physical conditions.
Link: https://doi.org/10.1093/mnras/stz677


T. Maiolino, P. Laurent, L. Titarchuk, M. Orlandini and F. Frontera, Red-skewed Kα iron lines in GX 13+1, published on April 30, 2019 on A&A, Volume 625, May 2019.
Context. Broad, asymmetric, and red-skewed Fe Kα emission lines have been observed in the spectra of low-mass X-ray binaries hosting neutron stars (NSs) as a compact object. Because more than one model is able to describe these features, the explanation of where and how the red-skewed Fe lines are produced is still a matter of discussion. It is broadly accepted that the shape of the Fe Kα line is strongly determined by the special and general relativistic effects occurring in the innermost part of the accretion disk. In this relativistic framework, the Fe fluorescent lines are produced in the innermost part of the accretion disk by reflection of hard X-ray photons coming from the central source (corona and/or NS surface). We developed an alternative and nonrelativistic model, called the WINDLINE model, that is capable to describe the Fe line features. In this nonrelativistic framework, the line photons are produced at the bottom of a partly ionized outflow (wind) shell as a result of illumination by the continuum photons coming from the central source. In this model the red-skewness of the line profile is explained by repeated electron scattering of the photons in a diverging outflow.
Aims. Examining the asymmetry of the fluorescent Fe K emission line evident in the XMM-Newton EPIC-pn spectra of the NS source GX 13+1, we aim to distinguish between the two line models. Because GX 13+1 is a well-known disk-wind source, it is a perfect target for testing the WINDLINE model and compare the spectral fits between the relativistic and nonrelativistic line models.
Methods. We used two XMM-Newton EPIC-pn observations in which the Fe line profiles were previously reported in the literature. These observations are not strongly affected by pile-up, and the Fe emission lines appear very strong and red-skewed. In order to access the goodness of the fit and distinguish between the two line models, we used the run-test statistical method in addition to the canonical χ2 statistical method. Results. The DISKLINE and WINDLINE models both fit the asymmetric Fe line well that is present in the XMM-Newton energy spectra of GX 13+1. From a statistical point of view, for the two observations we analyzed, the run-test was not able to distinguish between the two Fe line models, at 5% significance level.
Link: https://doi.org/10.1051/0004-6361/201833163


Loppini, Alessandro, Filippi, Simonetta; Stanley, H. Eugene, Critical transitions in heterogeneous networks: Loss of low-degree nodes as an early warning signal, published on April 2, 2019 in Phys. Rev. E 99, 040301(R).
A large number of real networks show abrupt phase transition phenomena in response to environmental changes. In this case, cascading phenomena can induce drastic and discontinuous changes in the system state and lead to collapse. Although complex network theory has been used to investigate these drastic events, we are still unable to predict them effectively. We here analyze collapse phenomena by proposing a minimal two-state dynamic on a complex network and introducing the effect of local connectivities on the evolution of network nodes. We find that a heterogeneous system of interconnected components presents a mixed response to stress and can serve as a control indicator. In particular, before the critical transition point is reached a severe loss of low-degree nodes is observed, masked by the minimal failure of higher-degree nodes. Accordingly, we suggest that a significant reduction in less connected nodes can indicate impending global failure.
Link: https://journals.aps.org/pre/abstract/10.1103/PhysRevE.99.040301


MAGIC Collaboration; Acciari, V. A.; Ansoldi, S.; Antonelli, L. A.; Arbet Engels, A.; Baack, D.; Babić, A.; Banerjee, B.; Barres de Almeida, U.; Barrio, J. A.; Becerra González, J.; Bednarek, W.; Bernardini, E.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.; Biland, A.; Blanch, O.; Bonnoli, G. Busetto, G.; Carosi, R.; Ceribella, G.; Cikota, S.; Colak, S. M.; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; D'Elia, V.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Lotto, B.; Delfino, M.; Delgado, J.; Di Pierro, F.; Do Souto Espiñera, E.; Domínguez, A.; Dominis Prester, D.; Dorner, D.; Doro, M.; Einecke, S.; Elsaesser, D.; Fallah Ramazani, V.; Fattorini, A.; Fernández-Barral, A.; Ferrara, G.; Fidalgo, D.; Foffano, L.; Fonseca, M. V.; Font, L.; Fruck, C.; Galindo, D.; Gallozzi, S.; García López, R. J.; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Giammaria, P.; Godinović, N.; Green, D.; Guberman, D.; Hadasch, D.; Hahn, A.; Herrera, J.; Hoang, J.; Hrupec, D.; Inoue, S.; Ishio, K.; Iwamura, Y.; Kubo, H.; Kushida, J.; Kuveždić, D.; Lamastra, A.; Lelas, D.; Leone, F.; Lindfors, E.; Lombardi, S.; Longo, F.; López, M.; López-Oramas, A.; Machado de Oliveira Fraga, B.; Maggio, C.; Majumdar, P.; Makariev, M.; Mallamaci, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Masuda, S.; Mazin, D.; Minev, M.; Miranda, J. M.; Mirzoyan, R.; Molina, E.; Moralejo, A.; Moreno, V.; Moretti, E.; Munar-Adrover, P.; Neustroev, V.; Niedzwiecki, A.; Nievas Rosillo, M.; Nigro, C.; Nilsson, K.; Ninci, D.; Nishijima, K.; Noda, K.; Nogués, L.; Nöthe, M.; Paiano, S.; Palacio, J.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Pedaletti, G.; Peñil, P.; Peresano, M.; Persic, M.; Prada Moroni, P. G.; Prandini, E.; Puljak, I.; Garcia, J. R.; Rhode, W.; Ribó, M.; Rico, J.; Righi, C.; Rugliancich, A.; Saha, L.; Sahakyan, N.; Saito, T.; Satalecka, K.; Schweizer, T.; Sitarek, J.; Šnidarić, I.; Sobczynska, D.; Somero, A.; Stamerra, A.; Strzys, M.; Surić, T.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Teshima, M.; Torres-Albà, N.; Tsujimoto, S.; van Scherpenberg, J.; Vanzo, G.; Vazquez Acosta, M.; Vovk, I.; Will, M.; Zarić, D., Deep observations of the globular cluster M15 with the MAGIC telescopes, published on Monthly Notices of the Royal Astronomical Society, Volume 484, Issue 2, April 2019, Pages 2876–2885.
A population of globular clusters (GCs) has been recently established by the Fermi-LAT telescope as a new class of GeV γ-ray sources. Leptons accelerated to TeV energies, in the inner magnetospheres of MSPs or in their wind regions, should produce γ-rays through the inverse Compton scattering in the dense radiation field from the huge population of stars. We have conducted deep observations of the GC M15 with the MAGIC telescopes and used 165 h in order to search for γ-ray emission. A strong upper limit on the TeV γ-ray flux <3.2×10−13cm−2s−1<3.2×10−13cm−2s−1 above 300 GeV (<0.26 per cent of the Crab nebula flux) has been obtained. We interpret this limit as a constraint on the efficiency of the acceleration of leptons in the magnetospheres of the MSPs. We constrain the injection rate of relativistic leptons, ηe, from the MSPs magnetospheres and their surrounding. We conclude that ηe must be lower than expected from the modelling of high-energy processes in MSP inner magnetospheres. For leptons accelerated with the power-law spectrum in the MSP wind regions, ηe is constrained to be much lower than derived for the wind regions around classical pulsars. These constraints are valid for the expected range of magnetic field strengths within the GC and for the range of likely energies of leptons injected from the inner magnetospheres, provided that the leptons are not removed from the GC very efficiently due to advection process. We discuss consequences of these constraints for the models of radiation processes around millisecond pulsars.
Link:
https://academic.oup.com/mnras/article-abstract/484/2/2876/5298496?redirectedFrom=fulltext


L Becerra K. Boshkayev, J. A. Rueda, R. Ruffini, Time evolution of rotating and magnetized white dwarf stars, published on May 20, 2019 in Monthly Notices of the Royal Astronomical Society.
We investigate the evolution of isolated, zero and finite temperature, massive, uniformly rotating and highly magnetized white dwarf stars under angular momentum loss driven by magnetic dipole braking. We consider the structure and thermal evolution of the white dwarf isothermal core taking also into account the nuclear burning and neutrino emission processes. We estimate the white dwarf lifetime before it reaches the condition either for a type Ia supernova explosion or for the gravitational collapse to a neutron star. We study white dwarfs with surface magnetic fields from 106 to 109 G and masses from 1.39 to 1.46 M_⊙ and analyze the behavior of the WD parameters such as moment of inertia, angular momentum, central temperature and magnetic field intensity as a function of lifetime. The magnetic field is involved only to slow down white dwarfs, without affecting their equation of state and structure. In addition, we compute the characteristic time of nuclear reactions and dynamical time scale. The astrophysical consequences of the results are discussed.
Links: https://doi.org/10.1093/mnras/stz1394; https://arxiv.org/abs/1812.10543


C. R. Argüelles, A. Krut, J. A. Rueda, R. Ruffini, Can Fermionic Dark Matter Mimic Supermassive Black Holes?, Article Winner of the Third Award in the "Gravity Research Foundation 2019 awards for essays on Gravitation", to be published in an special issue of the International Journal of Modern Physics D dedicated to the Essay Competition.
We analyze the intriguing possibility to explain both dark mass components in a galaxy: the dark matter (DM) halo and the supermassive dark compact object lying at the center, by a unified approach in terms of a quasi-relaxed system of massive, neutral fermions in general relativity. The solutions to the mass distribution of such a model that fulfill realistic halo boundary conditions inferred from observations, develop a highly-density core supported by the fermion degeneracy pressure able to mimic massive black holes at the center of galaxies. Remarkably, these dense core-diluted halo configurations can explain the dynamics of the closest stars around Milky Way's center (SgrA*) all the way to the halo rotation curve, without spoiling the baryonic bulge-disk components, for a narrow particle mass range mc2 ∼ 10-102 keV.
Link to the winners announcement:
https://www.gravityresearchfoundation.org/announcement
Link to the article:
https://static1.squarespace.com/static/5852e579be659442a01f27b8/t/5cd46772e4966b1d5dcd2e14/1557423988074/Arguelles%5Bc.a.%5D_Krut_Rueda_Ruffini_2019.pdf


J. A. Rueda, R. Ruffini, Y. Wang, Induced Gravitational Collapse, Binary-Driven Hypernovae, Long Gramma-ray Bursts and Their Connection with Short Gamma-ray Bursts, published on Mai 9, 2019 in Universe: Invited Review for the Special Issue "Accretion Disks, Jets, Gamma-Ray Bursts and Related Gravitational Waves".
Short and long Gamma-ray bursts (GRBs) originate in subclasses with specific energy release, spectra, duration, etc, and have binary progenitors. We review here the binary-driven hypernovae (BdHNe) subclass whose progenitor is a COcore-neutron star (NS). The supernova (SN) explosion of the COcore produces at its center a new NS (νNS) and triggers a hypercritical accretion onto the NS. The NS can become a more massive NS or collapse into a black hole (BH). We summarize this topic from the first analytic estimates in 2012 to the most recent three-dimensional (3D) smoothed-particle-hydrodynamics (SPH) numerical simulations in 2018. Long GRBs are richer and more complex than previously thought. The SN and the accretion explain X-ray precursors. The NS accretion, its collapse and the BH formation produce asymmetries in the SN ejecta, implying a 3D GRB analysis. The newborn BH surrounded by the ejecta and the magnetic field inherited from the NS, are the \emph{inner engine} from which the electron-positron (e⁺e⁻) plasma and the high-energy emission initiate. The e⁺e⁻ impact on the ejecta converts the SN into a hypernova (HN). The plasma dynamics in the ejecta explains the ultrarelativistic prompt emission in the MeV domain and the mildly-relativistic flares of the early afterglow in the X-ray domain. The feedback of the νNS emission on the HN explains the X-ray late afterglow and its power-law regime. All the above is in contrast with GRB models attempting to explain all the GRB phases with the kinetic energy of anultrarelativistic jet, as traditionally proposed in the "collapsar-fireball" model. In addition, BdHNe in their different flavors lead to νNS-NS or νNS-BH binaries. These binaries merge by gravitational wave emission producing short GRBs, establishing a connection between long and short GRBs and their occurrence rates.
Links: https://www.mdpi.com/2218-1997/5/5/110; https://arxiv.org/abs/1905.06050


Seddigheh Tizchang, Rohoollah Mohammadi, She-Sheng Xue, Probing Lorentz violation effects via a laser beam interacting with a high-energy charged lepton beam, published on The European Physical Journal C, March 2019, 79:224.
In this work, the conversion of linear polarization of a laser beam to circular one through its forward scattering by a TeV order charged lepton beam in the presence of Lorentz violation correction is explored. We calculate the ratio of circular polarization to linear one (Faraday Conversion phase ΔΦ_FC) of the laser beam interacting with either electron or the muon beam in the framework of the quantum Boltzmann equation. Regarding the experimentally available sensitivity to the Faraday conversion ΔΦ_FC≃10₋₃−10₋₂, we show that the scattering of a linearly polarized laser beam with energy k0∼0.1 eV and an electron/muon beam with flux ∈^¯_e,μ∼10₁₀/10₁₂ TeV cm₋₂ s₋₁ places an upper bound on the combination of lepton sector Lorentz violation coefficients c_μνcomponents (c_TT+1.4 c_(TZ)+0.25(c_XX+c_YY+2 c_ZZ)). The obtained bound on the combination for the electron beam is at the 4.35×10₋₁₅ level and for the muon beam at the 3.9×10₋₁₃ level. It should be mentioned that the laser and charged lepton beams considered here to reach the experimentally measurable ΔΦ_FC are currently available or will be accessible in the near future. This study provides a valuable supplementary to other theoretical and experimental frameworks for measuring and constraining Lorentz violation coefficients.
Link: https://link.springer.com/article/10.1140%2Fepjc%2Fs10052-019-6716-5