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SUMÁRIO
1. Destaques científicos: ICRANet recebe Prêmios do Concurso de Ensaios da Fundação para Pesquisa em Gravitação 2019
2. Renovação do acordo com ICRANet - UFRGS, 5 de abril de 2019
3. Dia da Ciência Armênia-Italiana, Yerevan, 15 de abril de 2019
4. ICRANet comunicado de imprensa: "Professor Roy Kerr nomeado Royal Society Fellow", 18 de abril de 2019
5. Visita de estudantes do programa Erasmus da escola ITIS Alessandro Volta, 7 de maio de 2019
6. Visita do Professor Ruffini a China, 10 - 22 de maio de 2019
7. Próximos encontros
8. Publicações recentes
1. Destaques científicos: ICRANet recebe Prêmios do Concurso de Ensaios da Fundação para Pesquisa em Gravitação 2019
2. Renovação do acordo com ICRANet - UFRGS, 5 de abril de 2019
3. Dia da Ciência Armênia-Italiana, Yerevan, 15 de abril de 2019
4. ICRANet comunicado de imprensa: "Professor Roy Kerr nomeado Royal Society Fellow", 18 de abril de 2019
5. Visita de estudantes do programa Erasmus da escola ITIS Alessandro Volta, 7 de maio de 2019
6. Visita do Professor Ruffini a China, 10 - 22 de maio de 2019
7. Próximos encontros
8. Publicações recentes
1. Destaques científicos: ICRANet recebe Prêmios do Concurso de Ensaios da Fundação para Pesquisa em Gravitação 2019
Fig. 1. Theoretical RAR rotation curves from 10-7 pc all the way to 105 pc, for three representative fermion masses in the mc2 keV region: 0.6 keV (dotted yellow curve), 48 keV (long-dashed-gray curve) and 345 keV (solid black curve).
O artigo "Can Fermionic Dark Matter Mimic Supermassive Black Holes?" by C. R. Argüelles, A. Krut, J. A. Rueda and R. Ruffini ficou em terceiro lugar na competição de 2019 da famosa Fundação para Pesquisa em Gravitação. www.gravityresearchfoundation.org O paper analisa a intrigante possibilidade de se explicar ambas as componentes de matéria escura numa galáxia: o halo de matéria escura e o objeto escuro supermassivo no seu centro, por meio de uma descrição unificada em termos de um sistema de fermions massivos, neutros e quase-relaxados em relatividade geral. As soluções para a distribuição de massa de tal modelo que satisfazem condições de contorno realistas para o halo, inferidas das observações, levam a um core superdenso sustentado pela pressão de degenerescência dos fermions, capaz de imitar buracos negros supermassivos nos centros de galáxias. Impressionantemente, essas configurações de cores superdensos com halos diluídos podem explicar a dinâmica das estrelas desde as mais próximas do centro da via láctea (SgrA*) até as partes dos halos nas curvas de rotação, sem corromper as componentes bariônicas do bojo-disco, para uma estreita faixa de massas das partículas, a saber mc2 ∼10-102 keV.
Para o artigo acesse: https://arxiv.org/abs/1905.09776
Para mais detalhes acesse: https://www.gravityresearchfoundation.org/s/2019abstracts.pdf
2. Renovação do acordo com ICRANet - UFRGS, 5 de abril de 2019
o dia 5 de Abril foi renovado o Acordo entre o ICRANet e a UFRGS (acrônimo para Universidade Federal do Rio Grande do Sul). O novo acordo foi assinado pelo Prof. Dr. Rui Vincente Oppermann (Reitor da UFRGS), pela Prof. Naira Maria Balzaretti (Diretora do Departamento de Física da UFRGS), pelo Prof. Dr. Dimiter Hadjimichef (Departamento de Física da UFRGS) e pelo Prof. Ruffini, Diretor da ICRANet. O acordo terá vigência de 5 anos; as atividades a serem desenvolvidas no âmbito do referido Protocolo de Cooperação consistirão de: promoção de atividades de pesquisa teorética e de observação relacionadas com as áreas de Astrofísica Relativística; ações conjuntas envolvendo o intercâmbio institucional do pessoal docente, dos pesquisadores, bolsistas de pós doutorado e estudantes; organização de atividades de ensino e investigação, seminários, conferências, workshop ou cursos de curta duração; publicações conjuntas.
Para o texto do acordo acesse: http://www.icranet.org/collaborationUFRGS.
3. Dia da Ciência Armênia-Italiana, Yerevan, 15 de abril de 2019
No 15 de abril de 2019, a ICRANet, em colaboração com a Academia Nacional de Ciências da Armênia (NASRA) e a Embaixada da Itália em Yerevan, organizou na cidade de Yerevan, na Armémia, o evento "Dia da Ciência da Armênia-Itália - Atividades conjuntas em Astrofísica Relativistica. Evento de Informação para Cooperação no campo da Astrofísica Relativistica". A sessão da manhã teve lugar nos espaços da Academia Nacional de Ciências, enquanto a sessão da tarde foi realizada na Embaixada da Itália.
Representantes institucionais da Arménia e de vários outros países participaram da conferência e promunciaram um breve discurso na sessão de abertura, a saber: Embaixador Ashot Kocharian (Ministério das Relações Exteriores da República da Armênia), Artak Apitonian (Vice-Ministro das Relações Exteriores da República da Armênia), Radik Martirosyan (Presidente da NASRA), Samvel Haroutiunian (Chairman da RA MES Science Committee), Vardan Sahakyan (vice-Chairman da RA MES Science Committee), Embaixador Vincenzo Del Monaco (Embaixada da Itália), Embaixador Matthias Kiesler (Embaixada da Alemanha) e Remo Ruffini (Diretor da ICRANet).
Durante a conferência, foram apresentados os mais recentes progressos científicos nos quais a ICRANet está trabalhando por eminentes professores e pesquisadore, a saber: Prof. Narek Sahakyan (ICRANet Armênia), Prof. Razmik Mirzoyan (Instituto Max Planck de Física, Alemanha), Dr Wang Yu (ICRANet), Rahim Moradi (ICRANet), Prof. Remo Ruffini (ICRANet), Dr Li Liang (ICRANet), Prof. Gregory Vereshchagin (ICRANet) Videoconferência, Prof. Paolo Giommi (ICRANet-ASI), Ashot Chilingaryan (Divisão de Raios Cósmicos) e Leonid Bezrukov (Vice-Diretor do Instituto de Pesquisa Nuclear em Moscou).
Na parte da tarde, o Prof. Ruffini encontrou o Presidente da República da Armênia, S.E. Armen Sarkissian, na residência dele em Yerevan, liderando uma delegação da ICRANet composta pelo Embaixador Ashot Kocharian, o Presidente Radik Martirosyan, o Prof. Narek Sahakyan, o Prof. Razmik Mirzoyan, o Prof. Paolo Giommi e o Prof. Massimo Della Valle. O Presidente Sarkissian salientou a importância das atividades da ICRANet na Armênia, pressionando por um forte desenvolvimento da educação e da ciência no país. O Prof Ruffini elogiou a cooperação com a Armênia e observou que tem intenção de implementar novos programas com os países da Ásia Central através da Armênia. Todos os participantes da reunião debateram sobre a possibilidades de implementar programas conjuntos bem como aprofundar a cooperação com os principais centros, organizações e universidades do mundo, como o ICRANet.
O evento terminou com o concerto "Primavera Italiana", organizado pela Embaixada Italiana e realizado no Komitas Chamber Music Hall. O concerto homenageou vários compositores de ópera italiana, como Arcangelo Corelli, Giovanni Pergolesi, Antonio Vivaldi e Niccolò Paganini.
Para mais detalhes sobre o evento acesse:
http://www.icranet.org/Armenian-ItalianScienceDay
Para fotos e vídeos acesse:
http://www.icranet.org/index.php?option=com_content&task=view&id=1240
Comunicado de imprensa:
http://www.icranet.org/index.php?option=com_content&task=view&id=1239
Representantes institucionais da Arménia e de vários outros países participaram da conferência e promunciaram um breve discurso na sessão de abertura, a saber: Embaixador Ashot Kocharian (Ministério das Relações Exteriores da República da Armênia), Artak Apitonian (Vice-Ministro das Relações Exteriores da República da Armênia), Radik Martirosyan (Presidente da NASRA), Samvel Haroutiunian (Chairman da RA MES Science Committee), Vardan Sahakyan (vice-Chairman da RA MES Science Committee), Embaixador Vincenzo Del Monaco (Embaixada da Itália), Embaixador Matthias Kiesler (Embaixada da Alemanha) e Remo Ruffini (Diretor da ICRANet).
Durante a conferência, foram apresentados os mais recentes progressos científicos nos quais a ICRANet está trabalhando por eminentes professores e pesquisadore, a saber: Prof. Narek Sahakyan (ICRANet Armênia), Prof. Razmik Mirzoyan (Instituto Max Planck de Física, Alemanha), Dr Wang Yu (ICRANet), Rahim Moradi (ICRANet), Prof. Remo Ruffini (ICRANet), Dr Li Liang (ICRANet), Prof. Gregory Vereshchagin (ICRANet) Videoconferência, Prof. Paolo Giommi (ICRANet-ASI), Ashot Chilingaryan (Divisão de Raios Cósmicos) e Leonid Bezrukov (Vice-Diretor do Instituto de Pesquisa Nuclear em Moscou).
Na parte da tarde, o Prof. Ruffini encontrou o Presidente da República da Armênia, S.E. Armen Sarkissian, na residência dele em Yerevan, liderando uma delegação da ICRANet composta pelo Embaixador Ashot Kocharian, o Presidente Radik Martirosyan, o Prof. Narek Sahakyan, o Prof. Razmik Mirzoyan, o Prof. Paolo Giommi e o Prof. Massimo Della Valle. O Presidente Sarkissian salientou a importância das atividades da ICRANet na Armênia, pressionando por um forte desenvolvimento da educação e da ciência no país. O Prof Ruffini elogiou a cooperação com a Armênia e observou que tem intenção de implementar novos programas com os países da Ásia Central através da Armênia. Todos os participantes da reunião debateram sobre a possibilidades de implementar programas conjuntos bem como aprofundar a cooperação com os principais centros, organizações e universidades do mundo, como o ICRANet.
O evento terminou com o concerto "Primavera Italiana", organizado pela Embaixada Italiana e realizado no Komitas Chamber Music Hall. O concerto homenageou vários compositores de ópera italiana, como Arcangelo Corelli, Giovanni Pergolesi, Antonio Vivaldi e Niccolò Paganini.
Para mais detalhes sobre o evento acesse:
http://www.icranet.org/Armenian-ItalianScienceDay
Para fotos e vídeos acesse:
http://www.icranet.org/index.php?option=com_content&task=view&id=1240
Comunicado de imprensa:
http://www.icranet.org/index.php?option=com_content&task=view&id=1239
4. ICRANet comunicado de imprensa: “Professor Roy Kerr nomeado Royal Society Fellow”, 18 de abril de 2019
O professor neo-zelandês Roy Kerr, matemático e físico, titular da Yevgeny Lifshitz Chair da ICRANet e Prêmio Crafoord em Astronomy para o ano de 2016, foi nomeado "Fellow" da Royal Society (UK) por suas excepcionais contribuições à ciência, o que o coloca entre os cientistas mais eminentes do mundo. A nomeaçã será oficializada em ocasião de uma cerimônia em Londres no dia 12 de julho de 2019.
A Royal Society concedeu ao professor Kerr esse prestigioso título "pela solução das equações de relatividade geral de Einstein para buracos negros em rotação, um resultado memorável agora conhecido como a métrica de Kerr, que descreve os buracos negros de Kerr. Entre as outras importantes contribuições está o trabalho presciente em soluções algébricas especiais de holonomia reduzida".
E realmente, o professor Roy Kerr em 1963 descobriu uma solução exata das equações de Albert Einstein sobre a relatividade geral de um objeto em rotação: "This mathematic solution – recorda o Prof. Ruffini – has allowed fundamental unprecedented advances in the applications in the fields of Physics, Astronomy and Relativistic Astrophysics: the applications extend to the field of the micro-physics of the elementary particles, such as the structure of the electron, to the astrophysics of Black Holes, which arise at the end of a star evolution, up to the most energetic processes in the universe, such as GRBs and the active galactic nuclei, where Black Holes and maxi-Black Holes, up to billions of times greater than our sun, dominate." It was indeed Remo Ruffini with John Archibald Wheeler who used the Kerr mathematic solution, introducing it in the description of the fundamental physics processes, giving them the name of "Black Hole", which has been then translated in all languages worldwide (Physics Today, 30, 1971). These topics have been further investigated by Blandford and Znajek (MNRAS, 179, 433, 1977) following an article by Ruffini and Wilson (Phys. Rev. D 12, 2959,1975).
A descoberta de Kerr provocou revolução no mundo da física, devido a sua grande importância. Daquele momento em diante, todos os trabalhos sobre buracos negros dependem fundamentalmente disso.
O Prof. Roy Kerr recebeu o Prêmio Marcel Grossmann em 2006 por ocasão do MG11 e tem ensinado na ICRANet dentro do programa IRAP PhD, o primeiro Doutorado Conjunto Internacional, fundado pela ICRANet e coordenado a nível internacional pela Universidade de Nice "Sophia Antipolis".
Professor Kerr has also been in the news this month after astronomers captured the first image of a black hole, attentively interpreted within ICRANet.
A Royal Society concedeu ao professor Kerr esse prestigioso título "pela solução das equações de relatividade geral de Einstein para buracos negros em rotação, um resultado memorável agora conhecido como a métrica de Kerr, que descreve os buracos negros de Kerr. Entre as outras importantes contribuições está o trabalho presciente em soluções algébricas especiais de holonomia reduzida".
E realmente, o professor Roy Kerr em 1963 descobriu uma solução exata das equações de Albert Einstein sobre a relatividade geral de um objeto em rotação: "This mathematic solution – recorda o Prof. Ruffini – has allowed fundamental unprecedented advances in the applications in the fields of Physics, Astronomy and Relativistic Astrophysics: the applications extend to the field of the micro-physics of the elementary particles, such as the structure of the electron, to the astrophysics of Black Holes, which arise at the end of a star evolution, up to the most energetic processes in the universe, such as GRBs and the active galactic nuclei, where Black Holes and maxi-Black Holes, up to billions of times greater than our sun, dominate." It was indeed Remo Ruffini with John Archibald Wheeler who used the Kerr mathematic solution, introducing it in the description of the fundamental physics processes, giving them the name of "Black Hole", which has been then translated in all languages worldwide (Physics Today, 30, 1971). These topics have been further investigated by Blandford and Znajek (MNRAS, 179, 433, 1977) following an article by Ruffini and Wilson (Phys. Rev. D 12, 2959,1975).
A descoberta de Kerr provocou revolução no mundo da física, devido a sua grande importância. Daquele momento em diante, todos os trabalhos sobre buracos negros dependem fundamentalmente disso.
O Prof. Roy Kerr recebeu o Prêmio Marcel Grossmann em 2006 por ocasão do MG11 e tem ensinado na ICRANet dentro do programa IRAP PhD, o primeiro Doutorado Conjunto Internacional, fundado pela ICRANet e coordenado a nível internacional pela Universidade de Nice "Sophia Antipolis".
Professor Kerr has also been in the news this month after astronomers captured the first image of a black hole, attentively interpreted within ICRANet.
5. Visita de estudantes do programa Erasmus da escola ITIS Alessandro Volta, 7 de maio de 2019
No dia 7 de Maio, uma delegação de estudantes do programa Erasmus e italianos do ITIS Alessandro Volta de Pescara visitou a ICRANet. Sob a supervisão do professor da ICRANet Gregory Vereshchagin, os alunos tiveram a oportunidade de visitar o centro e a biblioteca e participar das atividades científicas.
Após o discurso de abertura do Professor Vereshchagin, o Prof. She-Sheng Xue (ICRANet), Dr. Wang Yu (ICRANet), Dr. Liang Li (ICRANet), Rahim Moradi (ICRANet) e Yen-Chen Chen (ICRANet) falara sobre os mais recentes trabalhos científicos aos quais a ICRANet está trabalhando.
6. Visita do Professor Ruffini a China, 10 - 22 de maio de 2019
De 11 a 18 de maio, o professor Ruffini visitou a China, juntamente com o Dr. Yu Wang e o Dr. Li Liang. Durante essa visita, eles foram convidados a participar da conferência "Gamma-Ray Bursts and Related Astrophysics in Multi-Messenger Era", realizada no Centro Universitário de Nanjing de 13 a 17 de maio.
O Professor Ruffini apresentou a palestra "Self-similar structure of the ultra-relativistic prompt emission of GRB 190114C", o Dr. Wang Yu apresentou a palestra "GRB 190114C: most comprehensive portrait of gamma-ray burst" e o Dr. Liang Li apresentou a palestra "Shock breakout in BdHN I and BdHN II, the case of GRB 13027A, 180728A and 190114C".
Durante sua estada, o Prof. Ruffini visitou alguns pesquisadores chineses em Xangai na Universidade de Jiaotong e foi convidado pelo Professor Shing-Tung Yau, Diretor do Centro de Ciências Matemáticas de Yau, para visitar a Universidade de Tsinghua em Pequim, uma das mais importantes universidades chinesas. Nessa ocasião, o Prof. Ruffini teve uma reunião com o Prof. Yau e com o Prof. Shude Mao, Diretor do Departamento de Astronomia da mesma Universidade. Finalmente, o Prof. Ruffini chegou na cidade de Hefei onde encontrou o Prof. Ye-Fei Yuan, do Departamento de Astronomia da Universidade de Ciência e Tecnologia da China (USTC) e apresentou aos cientistas desta universidade os mais recentes progresso científicos nos quais a ICRANet está trabalhando.
Na sexta-feira, 17 de maio, o Prof. Remo Ruffini enviou uma importante mensagem da China, em ocasião do 40° aniversário da sua primeira visita à China:
"Quando introduzimos (eu e John Archibald Wheeler) o conceito de "buraco negro" em Princeton, nosso presságio era abrir uma nova era graças aos estudos de astrofísica relativística. Conversas diárias por telefone entre mim (em Princeton) e Riccardo Giacconi (em Harvard), tentando interpretar os dados do satélite UHURU ("liberdade" em Swaihili, lançado por Luigi Broglio da estação espacial San Marco no Quênia), fizeram desse presságio uma realidade. Em 1973, recebi o Prêmio Cressy Morrisom da academia de ciências de Nova Iorque pela descoberta do primeiro "buraco negro" na galáxia e, em 2002, Riccardo Giacconi recebeu o prêmio Nobel de física. Esse progresso foi marcado em 1973 por outro evento destinado a se tornar inesquecível: a descoberta das explosões de raios gamas (GRBs em inglês). Para entendê-las, foram necessários mais de 40 anos de estudos diários, acompanhados por desenvolvimentos tecnológicos e ópticos de "multimensageiros" sem precedentes na história da humanidade. Recentemente, há anúncios de um buraco negro no centro da galáxia, de buracos negros binários, de uma foto de um buraco negro com um rumor multimidiático imenso: muito interessante se verdadeiros, usando um eufemismo de Eugene Wigner. Graças ao GRB 190114C observado em 14 de Janeiro de 2019, identificamos pela primeira vez o nascimento/ a origem de um "buraco negro", o qual manifesta sua existência através de uma emissão de radiação pulsada da maior fonte de energia do universo em MeV, GeV e TeV. Uma "nova" fonte de energia, 1030 vezes maior que a bomba atômica de Los Alamos, com fluxo de partículas e energia 1042 e 1010 vezes, respectivamente, maiores que que o CERN e os aceleradores planejados na China no CEPC. Fermi abriu o caminho: com sua pesquisa em física nuclear, iniciou-se uma nova era econômica, política e militar. Aqueles que controlarão a ciência e tecnologia baseados nessa enorme fonte cósmica de energia também decidirão o futuro econômico, político e militar do nosso planeta."
O Professor Ruffini apresentou a palestra "Self-similar structure of the ultra-relativistic prompt emission of GRB 190114C", o Dr. Wang Yu apresentou a palestra "GRB 190114C: most comprehensive portrait of gamma-ray burst" e o Dr. Liang Li apresentou a palestra "Shock breakout in BdHN I and BdHN II, the case of GRB 13027A, 180728A and 190114C".
Durante sua estada, o Prof. Ruffini visitou alguns pesquisadores chineses em Xangai na Universidade de Jiaotong e foi convidado pelo Professor Shing-Tung Yau, Diretor do Centro de Ciências Matemáticas de Yau, para visitar a Universidade de Tsinghua em Pequim, uma das mais importantes universidades chinesas. Nessa ocasião, o Prof. Ruffini teve uma reunião com o Prof. Yau e com o Prof. Shude Mao, Diretor do Departamento de Astronomia da mesma Universidade. Finalmente, o Prof. Ruffini chegou na cidade de Hefei onde encontrou o Prof. Ye-Fei Yuan, do Departamento de Astronomia da Universidade de Ciência e Tecnologia da China (USTC) e apresentou aos cientistas desta universidade os mais recentes progresso científicos nos quais a ICRANet está trabalhando.
Na sexta-feira, 17 de maio, o Prof. Remo Ruffini enviou uma importante mensagem da China, em ocasião do 40° aniversário da sua primeira visita à China:
"Quando introduzimos (eu e John Archibald Wheeler) o conceito de "buraco negro" em Princeton, nosso presságio era abrir uma nova era graças aos estudos de astrofísica relativística. Conversas diárias por telefone entre mim (em Princeton) e Riccardo Giacconi (em Harvard), tentando interpretar os dados do satélite UHURU ("liberdade" em Swaihili, lançado por Luigi Broglio da estação espacial San Marco no Quênia), fizeram desse presságio uma realidade. Em 1973, recebi o Prêmio Cressy Morrisom da academia de ciências de Nova Iorque pela descoberta do primeiro "buraco negro" na galáxia e, em 2002, Riccardo Giacconi recebeu o prêmio Nobel de física. Esse progresso foi marcado em 1973 por outro evento destinado a se tornar inesquecível: a descoberta das explosões de raios gamas (GRBs em inglês). Para entendê-las, foram necessários mais de 40 anos de estudos diários, acompanhados por desenvolvimentos tecnológicos e ópticos de "multimensageiros" sem precedentes na história da humanidade. Recentemente, há anúncios de um buraco negro no centro da galáxia, de buracos negros binários, de uma foto de um buraco negro com um rumor multimidiático imenso: muito interessante se verdadeiros, usando um eufemismo de Eugene Wigner. Graças ao GRB 190114C observado em 14 de Janeiro de 2019, identificamos pela primeira vez o nascimento/ a origem de um "buraco negro", o qual manifesta sua existência através de uma emissão de radiação pulsada da maior fonte de energia do universo em MeV, GeV e TeV. Uma "nova" fonte de energia, 1030 vezes maior que a bomba atômica de Los Alamos, com fluxo de partículas e energia 1042 e 1010 vezes, respectivamente, maiores que que o CERN e os aceleradores planejados na China no CEPC. Fermi abriu o caminho: com sua pesquisa em física nuclear, iniciou-se uma nova era econômica, política e militar. Aqueles que controlarão a ciência e tecnologia baseados nessa enorme fonte cósmica de energia também decidirão o futuro econômico, político e militar do nosso planeta."
7. Próximos encontros
The Open Universe International Doctoral School, June 11 - 14, 2019
É com muito prazer que anunciamos o encontro Open Universe International Doctoral School sobre Magnetized Black Holes, GRBs, AGNs and the most violent Universe: from observation on data acquisition to the theory and model-building of GRB 190114C, uma conferência de 3 dias, que será realizada de 11 a 14 de Junho de 2019 na sede da ICRANet na Villa Ratti (Nice - França). O encontro foi organizado graças à colaboração entre o ICRANet, o LAPP (Laboratório de Anestesia de Física de Partículas) e o Instituto Max Planck de Física. O programa científico está em fase de preparação e mais detalhes sobre o evento serão publicados em breve na página web do evento: http://www.icranet.org/index.php?option=com_content&task=view&id=1241
16° simposio Ítalo-Coreano sobre Astrofísica Relativística
É com muito prazer que anunciamos o 16º Simpósio Italiano-Coreano sobre Astrofísica Relativista, que será realizado de 1 a 5 de Julho de 2019 na sede central da ICRANet. Os simposios Ítalo-Coreanos sobre Astrofísica Relativística são uma série de encontros bienais organizados alternadamente na Itália e na Coréia do Sul desde 1987. Os simpósios cobrem tópicos em astrofísica e cosmologia, tais como explosões de raios-gama e estrelas compactas, raios cósmicos de altas energias, energia e matéria escura, relatividade geral, e nova física associada à cosmologia. O programa científico está em fase de preparação e mais detalhes sobre o evento serão publicados em breve na página web do evento: http://www.icranet.org/index.php?option=com_content&task=view&id=1234
8. Publicações recentes
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]/Lbulge 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 ΔΦFC) 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 ΔΦFC≃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 cμνcomponents (cTT+1.4 c(TZ)+0.25(cXX+cYY+2 cZZ)). 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 ΔΦFC 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
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]/Lbulge 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 ΔΦFC) 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 ΔΦFC≃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 cμνcomponents (cTT+1.4 c(TZ)+0.25(cXX+cYY+2 cZZ)). 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 ΔΦFC 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