NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-26 T06:47:40 PDT
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For refcode 2008A&A...488..897H:
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Copyright by European Southern Observatory (ESO). Reproduced by permission
2008A&A...488..897H Wavelet analysis of a large sample of AGN at high radio frequencies Hovatta, T.; Lehto, H. J.; Tornikoski, M. Abstract. Aims. We have studied the characteristic timescales of 80 AGNs at 22, 37 and 90 GHz examining the properties of the wavelet method and comparing them to traditional Fourier-based methods commonly used in astronomy. Methods: We used the continuous wavelet transform with the Morlet wavelet to study the characteristic timescales. We also gain information when the timescale is present in the flux curve and if it is persistent or not. Results: Our results show that the sources are not periodic and changes in the timescales over a long time are common. The property of wavelets to be able to distinguish when the timescale has been present is superior to the Fourier-based methods. Therefore we consider it appropriate to use wavelets when the quasi-periodicities in AGNs are studied. Key words: galaxies: active, methods: statistical, radio continuum: galaxies
Retrieve 80 NED objects in this reference.
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