Infrared photometric study of SDSS selected narrow line Seyfert 1 galaxies

The infrared photometric study of SDSS selected Narrow Line Seyfert 1 Galaxies (NLS1s) is presented in this paper. We have made cross-identifications for such NLS1s with 2MASS and WISE observations. Finally 992 NLS1s have 2MASS and WISE counterparts. Comparisons of NLS1s with the Broad Line Seyfert 1 (BLS1s) and Seyfert 2 galaxies are made. It is shown that from 1 mu m to 5 mu m NLS1s are redder than BLS1s and Seyfert 2 galaxies possibly due to the richer dust environment in NLS1 nuclei or to the orientation effect while in the longer wavelengths those three kinds of sources have quite similar behavior indicative of radiation mainly from the similar warm starburst-related dust and the related AGN dust. In addition, relations between infrared colors and related (to H-beta) strengths of some important lines are also investigated. The results show that the related strengths of [Fell] 4570 angstrom are positively correlated with infrared colors in the 1-5 mu m region, but negatively correlated with infrared colors in the 12-22.pm region; the related strength of [OIII] 5007 angstrom are negatively correlated with infrared colors in the 1-5 pm region, but positively correlated with infrared colors in the 12-22 mu m region; the related strength of [NII]6583 angstrom are also negatively correlated with infrared colors in the 1-5 mu m region, but positively correlated with infrared colors in the 12-22 mu m region. Therefore it is indicated that the behavior of [Fell] 4570 angstrom is just opposed to that for [OIII] 5007 angstrom and [NII] 6583 angstrom This result may be caused by different origins of such lines. (C) 2017 Elsevier B.V. All rights reserved.