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Accueil > Séminaires > Archive des séminaires d’Utinam > 2018

Swayamtrupta Panda

Testing the physical driver of Eigenvector 1 in Quasar Main Sequence

vendredi 20 juillet 2018, 10h30

Salle de conférences de l’observatoire

Swayamtrupta PANDA

Center for Theoretical Physics / Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences

Résumé :

It has been just over 26 years since its inception that the concept of Eigenvector 1 in the context of the quasar main sequence was studied which still remains very attractive since it stresses correlations between various parameters and implies the underlying simplicity. Usually, the Eddington ratio was considered to be the main physical driver behind this sequence. In Panda et al. 2017, 2018, we test the hypothesis that the “actual driver is the peak of the broad band quasar spectrum, connected with the maximum temperature in the quasar accretion disk”. We perform the computations of the Fe II and Hbeta line production using the photoionisation code CLOUDY for a constant density single cloud model, and we locate the theoretical points on the optical plane. Our theoretically computed points cover well the optical plane part populated with the observed quasars, particularly if we allow for super-solar abundance of heavy elements. Explanation of the exceptionally strong Fe II emitter requires stronger contribution from the dark sides of the clouds. However, we conclude that there is “no single simple driver behind the sequence”, as neither Eddington ratio nor broad band spectrum shape play the dominant role.