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On the nature of the red, 2MASS selected AGN in the local Universe I: an optical spectroscopic study

We present optical spectra for a representative sample of 27 nearby (z < 0.2) 2MASS-selected AGN with red near-IR colours (J-K 2.0). The spectra were taken with the ISIS spectrograph on the WHT with the aim of determining the nature of the red 2MASS AGN, in particular whether they are young quasars obscured by their natal cocoon of gas and dust. We compare our findings with those obtained for comparison samples of PG quasars and unobscured type 1 AGN. The spectra show a remarkable variety, including moderately reddened type 1 objects (45%), type 1 objects that appear similar to traditional UV/optical selected AGN (11%), narrow-line Seyfert 1 AGN (15%), type 2 AGN (22%) and HII/composite objects (7%). The high Balmer decrements that we measure in many of the type 1 objects are consistent with their red J-KS colours being due to moderate levels of dust extinction (0.2 < E(B-V) < 1.2). However, we measure only modest velocity shifts and widths for the broader [OIII]λ5007 emission line components that are similar to those measured in the comparison samples. This suggests that the outflows in the red 2MASS objects are not unusual compared with those of optical/UV selected AGN of similar luminosity. In addition, the Eddington ratios for the 2MASS sample are relatively modest. Overall, based on their optical spectra, we find no clear evidence that the population of red, 2MASS selected AGN at low redshifts represents young quasars. Most plausibly, these objects are normal type 1 AGN that are moderately obscured by material in the outer layers of the circum-nuclear tori or in the disks of the host galaxies.