光學劇變類天體(OVVs)和蝎虎座BL天體(BL Lac objects)是活躍星系核(AGNs)的其 中一種型態。他們同樣有著非常快速的光變，也因此通常被合稱為躍變體(blazars). 但是，他們卻有著非常不同的光譜性質。光學劇變類天體的光譜有著寬譜線，但是， 蠍虎座BL天體卻沒有明顯的譜線。這篇論文的主要目的就是找出光學劇變類天體和蠍 虎座BL天體有甚麼不一樣的地方。我們從三方面來研究及比較躍變體：發射譜線的光 度，連續譜的光度密度，以及宿主星系。除此之外，在這篇論文裡，我們也考慮了電 波星系FRIs以及FRIIs的不同來幫助我們了解躍變體的不同之處。我們討論光學劇變 類天體和蠍虎座BL天體的不同，以及躍變體和電波星系之間的關係。 根據我們的結果，我們認為光學躍變類天體和電波型態的蠍虎座BL天體的宿主星系 和X-ray型態的蠍虎座BL天體的宿主星系不一樣，FRIs和FRIIs也有著不一樣的宿主星 系。躍變體和電波星系的宿主星系之間沒有一定的關係。因此，我們沒辦法從宿主星 系的研究來推論出變體與電波星系之間的統一模型理論。也許我們需要一個更複雜的 模型來解釋活躍星系核的謎題。 此外，我們發現說，光學劇變類天體的黑洞質量，和可見光的光度密度有著很強的 正相關(這裡的黑洞質量是用寬譜線得到的)。但是，我們也找到三個有著很大的黑洞 質量的光學躍變體但我們卻無法解析他們的宿主星系的有效半徑。這個結果也告訴我 們說，一般認為的黑洞質量和宿主星系的星等的關係在躍變體中也許是不存在的。或 者是說，我們無法從光學劇變類天體的寬譜線去推出合理的黑洞質量。;Optical violent variable quasars (OVVs) and BL Lac objects are known as a particular type of active galactic nuclei (AGNs) and are collectively referred to as "blazars". However, they do have very distinct spectral properties. The spectra of OVVs show broad emission lines while the BL Lac objects have no significant broad emission lines. In this work, we tried to figure out the differences between OVVs and BL Lacs. We investigated and compared the blazars in three aspects: the luminosities of emission lines, the continuum luminosity densities, and the properties of host galaxies. Besides, we also considered the radio galaxies FRIs and FRIIs in this thesis to help us distinguish the differences among blazars. We discussed the possible relation between the OVVs and BL Lac objects and investigated the relation between blazars and radio galaxies. Our results show that the OVVs and radio selected BL Lacs have different host galaxies with X-ray selected BL Lacs, and the FRIs and FRIIs also have different host galaxies. There are no obvious relation between the host galaxies of blazars and radio galaxies, thus we cannot connect the radio galaxies to the blazers by using a simple unification model from the study of the host galaxies of radio galaxies and blazars. We might need a more complicated unification model to solve this perplexing problem of AGNs. Apart from that, we also found a strong correlation between the optical luminosity densities and the black hole masses for OVVs; the black hole masses are derived from the broad line widths. However, we have found three OVVs having very large black hole masses but unresolved host galaxies. Our results indicate either that the black hole mass-bulge relation cannot apply to OVVs or that it is not reliable to use broad lines to derive the black hole masses for OVVs.
