Fechar
Metadados

@MastersThesis{Sousa:2019:MeGeOn,
               author = "Sousa, Manoel Felipe",
                title = "Mecanismos de gera{\c{c}}{\~a}o de ondas gravitacionais em 
                         an{\~a}s brancas de alta rota{\c{c}}{\~a}o",
               school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
                 year = "2019",
              address = "S{\~a}o Jos{\'e} dos Campos",
                month = "2019-02-27",
             keywords = "An{\~a} Branca, acre{\c{c}}{\~a}o de mat{\'e}ria, campo 
                         magn{\'e}tico, ondas gravitacionais, SGRs/AXPs, white dwarf, 
                         accretion of matter, magnetic field, gravitational waves, 
                         SGRs/AXPs.",
             abstract = "A detec{\c{c}}{\~a}o direta de Ondas Gravitacionais (OGs) tem 
                         proporcionado novos ramos de estudos cient{\'{\i}}ficos e 
                         levantado novos questionamentos sobre o comportamento dos sistemas 
                         astrof{\'{\i}}sicos. Devido a esses grandes avan{\c{c}}os e a 
                         busca pelo entendimento de fontes astrof{\'{\i}}sicas que emitem 
                         OGs na faixa de frequ{\^e}ncias de 10\−4 a 10\−1 
                         Hz, esfor{\c{c}}os t{\^e}m sido feitos para o desenvolvimento de 
                         detectores espaciais, tais como, o LISA (Laser Interferometer 
                         Space Antenna), o BBO (Big Bang Observer) e o DECIGO (DECi-hertz 
                         Interferometer Gravitational wave Observatory), com o intuito de 
                         observar essas fontes que n{\~a}o podem ser medidas com 
                         detectores terrestres. Uma das classes candidatas a serem 
                         detectadas por esses instrumentos espaciais s{\~a}o as an{\~a}s 
                         brancas (ABs) de alta rota{\c{c}}{\~a}o. Essas ABs s{\~a}o 
                         remanescentes peculiares que emitem pulsos de energia apresentando 
                         per{\'{\i}}odos de rota{\c{c}}{\~a}o da ordem de segundos a 
                         poucos minutos e possuem intensos campos magn{\'e}ticos (106 G a 
                         109 G). Essa classe estelar tem dado suporte a um modelo 
                         alternativo para descrever uma classe de pulsares conhecida como 
                         Soft Gamma Repeaters (SGRs) e Anomalous X \− Ray Pulsars 
                         (AXPs), onde esses s{\~a}o caracterizados como pulsares de ABs 
                         alimentados pela rota{\c{c}}{\~a}o. Nessa 
                         disserta{\c{c}}{\~a}o, analisamos dois mecanismos de 
                         gera{\c{c}}{\~a}o de OGs em ABs de alta rota{\c{c}}{\~a}o: 
                         acre{\c{c}}{\~a}o de mat{\'e}ria quando essas se encontram em 
                         um sistema bin{\'a}rio, e deforma{\c{c}}{\~a}o na estrutura da 
                         estrela em raz{\~a}o do intenso campo magn{\'e}tico. Para isso, 
                         calculamos a amplitude e a energia gravitacional para 3 sistemas 
                         bin{\'a}rios: AE Aquarii, AR Scorpii e RX J0648.0-4418 
                         considerando os dois processos de emiss{\~a}o de OGs. Ainda, 
                         investigamos, pela primeira vez na literatura, a contrapartida 
                         gravitacional dos SGRs/AXPs considerando o formalismo de ABs. Para 
                         essa an{\'a}lise, aplicamos apenas o mecanismo de 
                         deforma{\c{c}}{\~a}o magn{\'e}tica. Ap{\'o}s o c{\'a}lculo, 
                         conclu{\'{\i}}mos que, para o primeiro mecanismo, os sistemas AE 
                         Aquarii e RX J0648.0-4418 s{\~a}o bons candidatos a serem 
                         observados pelo BBO e DECIGO se possu{\'{\i}}rem um amontoado de 
                         massa em um dos polos magn{\'e}ticos (delta)m \≥ 
                         10\−5M. para 1 ano de observa{\c{c}}{\~a}o, enquanto que 
                         para o segundo mecanismo, os 3 sistemas analisados necessitam que 
                         a AB tenha um campo magn{\'e}tico em torno de 2 ordens de 
                         magnitude maiores do que s{\~a}o inferidos pela emiss{\~a}o 
                         eletromagn{\'e}tica (107 G a 108 G). Al{\'e}m disso, com o 
                         segundo mecanismo, foi encontrado que alguns SGRs/AXPs podem ser 
                         observados pelo BBO e DECIGO: 1E 1547.0-5408 e SGR 1806-20 
                         s{\~a}o fontes que podem ser observadas para todo o intervalo de 
                         massa considerado (0, 6M. \≤ MAB \≤ 1, 4M.) em 1 ano 
                         de observa{\c{c}}{\~a}o, j{\'a} as fontes SGR 1900+14, CXOU 
                         J171405.7-381031, Swift J1834.9-0846 e SGR1627-41 ser{\~a}o 
                         detectadas com um tempo de observa{\c{c}}{\~a}o de 5 anos para o 
                         mesmo intervalo de massa. Com isso, uma poss{\'{\i}}vel 
                         detec{\c{c}}{\~a}o de OGs cont{\'{\i}}nuas provindas desses 
                         objetos corroboraria com o modelo de pulsares de ABs, pois notamos 
                         que os SGRs e AXPs, no modelo de magnetar (estrelas de 
                         n{\^e}utrons altamente magnetizadas), est{\~a}o muito abaixo das 
                         curvas de sensibilidade do BBO e DECIGO e n{\~a}o ser{\~a}o 
                         detectados por esses instrumentos com esse mecanismo. ABSTRACT: 
                         The direct detection of gravitational waves (GWs) provided new 
                         branches of scientific studies and raised new questions about the 
                         behavior of astrophysical systems. Due to these great advances and 
                         the search for understanding of astrophysical sources that emit 
                         GWs in the frequency range of 10\−4 to 10\−1 Hz, 
                         efforts have been made for the development of space detectors such 
                         as, LISA (Laser Interferometer Space Antenna), BBO (Big Bang 
                         Observer) and DECIGO (DECi-hertz Interferometer Gravitational wave 
                         Observatory), in order to observe these sources that cannot be 
                         measured with terrestrial detectors. One of the candidate classes 
                         to be detected by these spatial instruments are the fast-rotating 
                         white dwarf (fast-rotating WDs). These WDs are peculiar remnants 
                         that emit pulses of energy presenting rotation periods of the 
                         order of seconds to a few minutes and have intense magnetic fields 
                         (106 G to 109 G). This stellar class supports an alternative model 
                         to describe a class of pulsar known as Soft Gamma Repeaters (SGRs) 
                         and Anomalous X-Ray Pulsars (AXPs), where, in this model, these 
                         objects are characterized as WD pulsars powered by rotation. In 
                         this work, we analyzed two mechanisms of GWs emission in 
                         fast-rotating WDs: acrection of matter when these ones are in a 
                         binary system, and deformation of the structure of the star due to 
                         the strong magnetic field. For this, we calculated the 
                         gravitational amplitude and energy for 3 binary systems: AE 
                         Aquarii, AR Scorpii and RX J0648.0-4418, considering the two 
                         processes of GW emission. We also investigated, for the first time 
                         in the literature, the gravitational counterpart of the SGRs/AXPs 
                         considering the formalism of WDs. For this analysis, we applied 
                         only the magnetic deformation mechanism. After the calculation, we 
                         concluded that, for the first mechanism, the systems AE Aquarii 
                         and RX J 0648.0- 4418 are good candidates to be observed by BBO 
                         and DECIGO if they have an amount of accumulated mass on one of 
                         the magnetic poles of (delta)m \≥ 10\−5M. for 1 year 
                         of observation, while, for the second mechanism , the 3 analyzed 
                         systems require that WD has a magnetic field around 2 orders of 
                         magnitude higher than that is inferred by electromagnetic emission 
                         (107 G a 108 G). In addition, using the second mechanism, it was 
                         found that some SGRs/AXPs can be observed by BBO and DECIGO: 1E 
                         1547.0-5408 and SGR 1806-20 are sources that can be observed for 
                         the entire considered mass range (0, 6M. \≤ MAB \≤ 
                         1, 4M.) in 1 year of observation, for the sources SGR 1900+14, 
                         CXOU J171405.7-381031, Swift J1834.9-0846 and SGR 1627-41 will be 
                         detected with a 5-year observation time for the same mass range. 
                         Thereby, a possible detection of continuous GWs originated from 
                         these objects is a good indication that corroborates with the WD 
                         pulsar model because we noted that the SGRs and AXPs, in the 
                         Magnetar model (highly magnetized neutron stars), are far below 
                         the sensitivity curves of BBO and DECIGO and will not be detected 
                         by these instruments using this mechanism.",
            committee = "Rodrigues, Cl{\'a}udia Vilega (presidente) and Ara{\'u}jo, 
                         Jos{\'e} Carlos Neves de (orientador) and Coelho, Jaziel Goulart 
                         (orientador) and Aguiar, Odylio Denys de and Alves, M{\'a}rcio 
                         Eduardo da Silva",
         englishtitle = "Gravitational wave emission mechanisms in fast-rotating white 
                         dwarfs",
             language = "pt",
                pages = "107",
                  ibi = "8JMKD3MGP3W34R/3SNU748",
                  url = "http://urlib.net/rep/8JMKD3MGP3W34R/3SNU748",
           targetfile = "publicacao.pdf",
        urlaccessdate = "23 nov. 2020"
}


Fechar