Optical-Infrared Spectroscopic Investigation Of Some Special AGNs

The study to the co-evolution of central black holes and galaxies through the Active Galactic Nuclei(AGN)phase is one of the most important issue in contemporary astrophysics.In AGN,the accretion disk is the main medium for the accretion gas and growth of the black hole.As a remarkable feature on the spectrum,the double-peaked broad emission lines are a useful probe to explore to study the characters of accretion disks.However,due to limitations of obser-vations,previous studies of the double-peaked broad emission lines has mainly focused on H?,and little known about the physical properties of the accretion disk,such as gas density,by means of photoionization.Besides the accretion of black hole,the feedback of AGNs to host galaxies is another important pic-ture of the co-evolution.Among the various feedback mechanisms,outflow is the most common form of black hole.It is mainly observed as broad absorption lines(BALs)and blueshifted emission lines.However,there are still some issues un-derexplored in the study of the emission lines and absorption lines of the outflow,such as the blue-shifted low-ionization emission line from the outflow,the rela-tionship between the emission line and the absorption line in the outflow of the broad emission line region(BLR),and the very fast blueshifted[O?]outflows,etc.These are the themes of this dissertation and we will mainly focus on some unusual quasars,where some important properties are more clearly revealed.(1)In a famous radio loud disk-emitting AGN,3C 332,we obtained the quasi-simultaneous optical-near infrared(NIR)spectroscopy of the radio loud quasar,3C 332.Besides the H?,we first detect the double-peaked HeI ?10830(+Pa?)and Pa? in the NIR spectra.Meanwhile,in the optical spectrum,another double-peaked emission line can be obtained at the blue-side of H?,which we identified to be HeI ?5877.There is no obvious difference among these double-peaked profiles.These double-peaked profiles can be well reproduced by the circular disk model.With the help of photoionization model,we can successfully constrain the density of disk-emitting gas under the assumption of uniform density.A more models are also considered,in which simulation the density distribution of the disk normal direction is assumed to be in the form of ne(z)? 10z/lo,where z is the depth from the surface of disk and the log l0(cm)can be also well constrained.both models can reproduce all the double-peaked intensity ratios except H?/Pa?.The X-ray observation indicates a intrinsic absorber exists and the dust reddening can be inferred in 3C 332.Considering the effect of dust reddening,the improved uniform density model can generate all the observed intensity ratios and the corresponding density range is nearly same with the previous uniform density model.However,the dust reddening can not help the multi-density model to reproduce the observed H?/Pa?.This implies that the structure of disk-emitting gas might be more complicated.(2)We present a detailed study of the optical and NIR emission and ab-sorption line spectrum of the quasar SDSS J163345.22+512748.4(hereafter SDSS J1633+5127).We found that the bulk of both Mg ?and UV Fe?,are blueshifted with a velocity of?2200 km s-1 with respect to the quasar systelic redshift.This blueshifted component can be also detected in Habroad emission line(BEL).We constrained the covering factor Cf,density nH,column density NH and an ion-ization parameter UE through these blueshifted BELs.This outflow gas is located at a scale comparable to the BLR.Also,we discovered HeI*10830,Mg ?,and He I*3889BALs in the spectrum.The density of the BAL outflow cannot be con-strained through these BALs.Assuming that the BAL gas is thick enough for a full development of the ionization front,we can infer an ionization parameter UA for the BAL outflow and This UA is similar to the UE.However,the total column density of the BAL outflow is constrained about two orders of magnitude smaller than that of blueshifted BEL outflow.A toy kinetic model has been proposed to reproduce the profiles of blueshifted Mg ? emission line and Mg ? BAL under the assumption that the BAL outflow and blueshifted emission line outflow have the same density,ionization parameter but different column densities.Due to the unlimited density of BAL outflow,the observation of SDSS J1633+5127 cannot provide the sufficient evidence for this assumption.In another BAL quasar SDSS J075133.35+134548.3(hereafter SDSS J0751+1345),we detected the HeI*10830,He I*3889,Mg? and Al? BALs in its optical and NIR spectra.With the BALs from different ions,we can limit the properties of a BAL outflow and found that this BAL outflow is also locate near the BLR of SDSS J0751+5127.The column density and ionization parameter of SDSS J0751+5127 are very close to these characters of BAL outflow in SDSS J1633+5127.Fortunately,the density of the BAL outflow in SDSS J0751+5127 can be well constrained and the value is similar with the nH of blueshifted BEL outflow of SDSS J1633+5127.This indicates that,our assumption above is acceptable.To further study the properties of outflows with blueshifted low-ionization BELs,we complied a small sample of 16(include SDSS J1633+5127)quasars whose Mg? BEL peaks have a blueshifted velocity larger than 1500 km s-1.In several of these quasars,we found that the H? are also significantly blueshifted with respect to the low-ionization narrow emission lines.In this sample,the fraction of BAL quasar is much higher than that of normal quasars.In a sample of 74 quasars with optical and NIR spectra,out of which 5 peculiar quasars with blueshift[O ?]emission line outflow.The largest blueshift velocities of[O ?]in the 5 quasars are larger than 7000 km s-1.Incorporating the corresponding blueshifted Mg? and C? lines,we constrained the density of the outflow close to the critical density of[O ?].The distance of the outflows is about several to twenty pc from the central engine,which is at the inner boundary of narrow line region.