Seminários GIFT – Sessão especial

Apresentação: A astronomia das ondas gravitacionais é um campo vasto e em expansão, já que observações eletromagnéticas não são mais a única forma de explorar o Universo. Tal campo surgiu como uma disciplina distinta, fornecendo percepções únicas e valiosas sobre as propriedades e processos do Universo físico.

 A primeira observação da fusão de dois buracos negros foi feita pelos interferômetros LIGO marcando o início da astronomia das ondas gravitacionais (GW150914, Abbott et al. 2016a). Em 17 de agosto de 2017, os instrumentos LIGO-Virgo observaram um evento inédito: ondas gravitacionais geradas pela fusão de dois objetos compactos de baixa massa consistente com uma estrela de nêutrons (BNS, GRB170817). Este evento único também gerou uma curta emissão em raios gamma contemplando um ramo de astronomia a comunidade científica, a astrônomia multimensageira de ondas gravitacionais.

 Devido à grande variedade de sinais potenciais relacionados a astronomia multimensageira, a análise do tipo \”burst\” utiliza uma gama de estratégias de detecção, desde pesquisas focadas em objetos astrofísicos razoavelmente bem modelados até métodos de pesquisa que são projetados para detectar sinais com formas de onda completamente arbitrárias. Em específico, a análise chamada “target burst search” utiliza as informações do mensageiro eletromagnético, como o tempo e a posição no céu, na análise dos dados dos eventos de ondas gravitacionais fazendo com que esse tipo de análise 20% mais sensível do que a análise do tipo “all-sky”. Análises feitas com o intuito de procurar ondas gravitacionais com contrapartidas em raios gamma e rádio são realizadas pela colaboração LIGO-Virgo.

Speaker: Iara Tosta e Melo (UNISS)

Títle: Search for GW and multimessenger events during LIGO/Virgo era

Abstract: Nowadays, observation of astrophysical sources via non-electromagnetic messengers has presented enormous challenges as messengers of non-electromagnetic origin were observed such as neutrinos from core-collapse supernova SN 1987A, high-neutrinos in coincidence with the BLLac object TXS 0506+056, and most recently the detection of gravitational waves (GWs) in 2015. The new multi-messenger astronomy is an extension to traditional multi-wavelength astronomy as electromagnetic observations are no longer the only way of exploring the Universe.  Such a field has emerged as a distinct discipline providing unique and valuable insights into the properties and processes of the physical Universe. The first observations from the inspiral and merger of a binary black-hole system (BBH) by the advanced LIGO interferometers marked the onset of GW astronomy (GW150914, Abbott et al. 2016a). On 17 August 2017, multi-messenger astronomy related to GWs had its breakthrough: the LIGO-Virgo network observed a GW signal of two low-mass compact objects consistent with a neutron star binary (GRB170817, GRB170817A, Abbott et al. 2017a,b). Nonetheless, a wide range of highly energetic astrophysical phenomena is expected to be accompanied by the emission of GWs and/or both GWs EM within the LIGO, Virgo, and Kagra collaboration instruments’ frequency band.

Speaker: Danielle Dell\’Aquila (UNISS)

Title: A novel multi-layer modular approach for real-time gravitational-wave detection

Abstract: Advanced LIGO and Advanced Virgo ground-based interferometers are poised to probe an unprecedentedly large volume of space, enhancing the discovery power of the observations to even new sources of gravitational wave emitters. In this scenario, the development of highly optimized gravitational wave detection algorithms is crucial. We propose a novel framework for real-time detection of gravitational waves inspired by speech processing techniques and based on artificial intelligence approaches. The key aspects of the newly proposed framework are: (i) the layered approach, (ii) the high modularity, (iii) the low computational complexity. The talk describes the basic concepts of the framework and the derivation of a ground model, ideal to be used as the first layer of the framework. The proposed model is derived using a novel hybridization of genetic programming and artificial neural networks. To train and test the model, we used simulated binary black hole gravitational wave waveforms in synthetic Gaussian noise representative of state-of-the-art Advanced LIGO sensitivity design. Compared to more complex approaches, such as convolutional neural networks, our framework, even using the simple ground model described in the paper, has similar performance but with a much lower computational complexity and a higher degree of modularity. The newly proposed framework is ideal to be integrated in real-time multi-layer pipelines for gravitational-wave detection with second generation interferometers.

Speaker: Davide Rozza (UNISS)

Title: The Sar-Grav Laboratory, a seed of ET

Abstract: Located in Sardinia close to Lula, the region of the Sos Enattos former mine is under studies to host the third generation of gravitational wave interferometer: Einstein Telescope (ET). The Sar-Grav laboratory, a seed of ET, will host underground experiments, cryogenic payloads, low frequency and cryogenic sensor development that need low seismic and anthropogenic noise. Indeed, the Sos Enattos area already hosts seismometer and magnetometer nets, located both on the surface and underground, that prove the quietness of the site. SarGrav also host the Archimedes experiment, an experiment aimed to study the interaction of vacuum fluctuations with gravity.

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