Uso do periodograma de lomb e da transformada Wavelet para detecção de periodicidades em radiofontes extragalácticas
Tipo
Tese
Data de publicação
2016-12-16
Periódico
Citações (Scopus)
Autores
Gastaldi, Marcio Ribeiro
Orientador
Botti, Luiz Claudio Lima
Título da Revista
ISSN da Revista
Título de Volume
Membros da banca
Szpigel, Sérgio
Correia, Emilia
Cecatto, José Roberto
Souza, Carlos Alexandre Wuensche de
Correia, Emilia
Cecatto, José Roberto
Souza, Carlos Alexandre Wuensche de
Programa
Ciências e Aplicações Geoespaciais
Resumo
In the present work we applied the Lomb periodogram and the wavelet transform to the light curves of three extragalactic radio sources observed by the Michigan radio telescope at 4.8 GHz, 8.0 GHz and 14.5 GHz.
The results obtained using the two spectral analysis tools are complimentary to each other in the sense that the wavelet transform provided the perspective of the temporal behavior of the Lomb periodogram content.
In order to take into account as much information as possible, we included VLBI data to the analysis of explosions detected in the radio light curves. Moreover, we searched for correlation between the zero-separation times and maxima/minima found in the periodicities curves revealed by the wavelet transform.
In the case of the quasar OJ287 we found a new oscillatory behavior in the ~1.6 yr periodicity detected by Hughes et al. (1999). This modulation showed a ~6 yr period sinusoidal profile that agrees with the existence of a binary of black holes regulating the ejection rate of plasmons from the central region of OJ287.
We detected approximately 1.6 yr and 3.3 yr periodicities of the quasar OV236. As a future work, these periodicities and their temporal behavior could be associated to the accretion dynamics of its black hole/disk.
We added the radio source 0333+321 to the present essay because it presents excellent sampling and a much higher redshift when compared to OJ287 and OV236.
We also plotted the spectra of selected outbursts and calculated the parameters of the related radio emission regions such as the variability radius and the brightness temperature.
Descrição
Palavras-chave
quasares , contínuo rádio , Fourier , Wavelet
Assuntos Scopus
Citação
GASTALDI, Marcio Ribeiro. Uso do periodograma de lomb e da transformada Wavelet para detecção de periodicidades em radiofontes extragalácticas. 2016. 150 f. Tese (Ciências e Aplicações Geoespaciais) - Universidade Presbiteriana Mackenzie, São Paulo .