A Multiwavelength study of NLS1s galaxies from the Second Byurakan Survey

Abstract

In this work we present a multiwavelength study of narrow-line Seyfert 1 galaxies (NLS1s) discovered in the Second Byurakan Survey (SBS). The sample consists of 26 objects, which have $M_B\ge -23.0$, or $-19.9>M_B>-23.0$, $0.0243<z<0.317$ and $15.2<B<19.0$. For these objects, we present accurate coordinates, magnitudes, redshifts and the identification of optical objects with X-ray, IR and radio sources. Several galaxies are identified as X-ray or radio sources for the first time. We also report spectroscopic and photometric data, the spectral energy distribution, $\hat{I}{\pm }_{ox}$ indices and other data. Our study shows that SBS NLS1s are strong or moderately strong soft X-ray sources with $\log L_x=42.8-45.4$. Soft X-ray luminous sources in our sample do not tend to be luminous in the infrared. All SBS NLS1s are radio quiet objects ($\log L_R<40.0$), and 52% of them are strong FeII emitters (FeII$\lambda 4570/H{\hat{I}}^2>1$). The traditional linear correlation $L_x$ and $L_{op}$, which seems to hold for AGN in general, is found for SBS NLS1s. An anticorrelation between FWHM of $H{\hat{I}}^2$ and the ratio of FeII$\lambda 4570/H{\hat{I}}^2$ is also observed. A weak correlation is found between $\hat{I}{\pm }_{ox}$ slope and $L_{op}$. One of our main findings is that almost all SBS NLS1s may not have a FIR bump. Their SED suggest that they may also possess a BBB. The absence of IR bump in most of SBS NLS1s and the weakness of X-ray radiation in some of them, may argue against the presence of a BLR. The surface density of SBS NLS1s is $<$ 0.015 per $deg{.}^2$ ($B<17.5,z<0.16$).

44 pages, 8 figures, published ApJ May 2003