Daftar Isi: Optical Spectroscopy of nearby type1-LINERs

Daftar Isi:

I will present the highlights from our recent study of 22 local (z<0.025) type-1 LINERs from the Palomar Survey, on the basis of optical long-slit spectroscopic observations taken with TWIN/CAHA, ALFOSC/NOT and HST/STIS (Cazzoli et al. 2018). Our goals were threefold: explore the AGN-nature of these LINERs by studying the broad (BLR-originated) Hβ component; derive reliable interpretation for the multiple narrow components of emission lines by studying their kinematics and ionization mechanism (via standard BPTs); probe the neutral gas in the nuclei of these LINERs for the first time. Hence, kinematics and fluxes of a set of emission lines, from Hβ λ4861 to [S II] λλ6716, 6731, and the NaD λλ5890, 5896 doublet in absorption have been modelled and measured, after the subtraction of the underlying starlight. We found that the broad Hβ component is sometimes elusive in our ground-based spectroscopy, whereas it is ubiquitous for space-based data. By combining optical diagnostic diagrams, theoretical models [for AGNs, post-asymptotic giant branch (pAGB) stars, and shocks and the weak/strong-[OI] classification, we exclude the pAGB star scenario in favour of the AGN as the dominant mechanism of ionization in these LINERs, being shocks however relevant. The kinematical properties of the emission lines may indicate the presence of ionized outflows, preferentially seen in [OI]. However, the neutral gas outflows, diagnosed by NaD, would appear to be less frequent.