Properties of Broad Band Continuum of Narrow Line Seyfert 1 Galaxies

Abstract

We have performed a statistical study of the properties of the broad band continuum of Narrow Line Seyfert 1 galaxies (NLS1s) by collecting ratio, infrared, optical and X-ray continuum data from various databases and compared the results with control samples of Broad Line Seyfert 1 galaxies (BLS1s). We find that the fraction (∼ 6%) of Radio Loud (RL) NLS1s is significantly less than that of BLS1s (∼ 13%), which is caused by the lack of radio-very-loud sources in the former. The rarity of RL NLS1s, especially radio-very-loud ones, is consistent with the scenario of small black hole and high accretion rate for NLS1s. Six new radio loud NLS1s are found and five RL NLS1 candidates are presented. In comparison with the BLS1s, the NLS1s tend to have stronger far infrared emission, cooler infrared colors and redder B − K color, which suggests that NLS1s are hosted by dust-richer nuclei. The NLS1s also show steeper soft X-ray spectrum and large soft X-ray to optical flux ratio, while a significant fraction show flat soft X-ray spectra. At least two factors can account for this, absorption and spectral variability. We also perform a correlation analysis between various broad band data. It is found that most correlations identified for NLS1s are also valid for radio quiet BLS1s: (1) the optical colors are anti-correlated with X-ray spectral index; (2) higher optical, Xray and NIR luminosity objects show bluer optical colors and red H − K color; (3) higher luminosity objects show warmer IRAS color; (4) the radio loudness correlates with B − K and X-ray to optical flux ratio. Radio loud objects behave somewhat differently in a few correlations.

A Narrow-Line Seyfert 1-Blazar Composite Nucleus in 2MASX J0324+3410

“…The radioto-optical SED of the radio-loud NLS1 J094857.3ϩ002225, for which beaming is required to explain the high brightness temperature, is also similar to that of 2MASX J0324ϩ3410 (Zhou et al 2003;also Doi et al 2006). A third example is RX J16290ϩ4007 (Zhou & Wang 2002; see also Komossa et al 2006b), a flat-spectrum radio quasar with NLS1 characteristics in the optical. Furthermore, eight out of the nine VRL Wang et al (2006) from their high radio brightness temperature, but with more extreme optical properties.…”

“…about two dozen radio-loud (RL) NLS1s (Grupe et al 2000;Zhou & Wang 2002;Zhou et al 2003Zhou et al , 2005Zhou et al , 2006Komossa et al 2006aKomossa et al , 2006b. Given the intriguing fact that RL AGNs and "normal" NLS1s occupy the opposite extremes of the E1 parameter space (Boroson 2002), the study of RL NLS1s may provide important clues to understanding the physical drivers of E1.…”

Narrow-line Seyfert 1 galaxies at hard X-rays★

“…This is the case with IGR J16185−5928 and IGR J19378−0617 with Hβ > 2000 km s −1 but classified as NLSy1 galaxies based on their [O iii ] λ5007/Hβ and Fe ii /Hβ ratios. Also in ESO 399‐IG 020, the Hβ FWHM is slightly above 2000 km s −1 and the source was originally reported as a type 1 Seyfert in Zhou & Wang (2002); lately, the source has been re‐classified as a NLSy1 galaxy by Dietrich et al (2005) (although the authors do not report emission‐line ratios, but only the Hβ FWHM and its flux, that is, 1.2 × 10 −13 erg cm −2 s −1 ). In Osterbrock & De Robertis (1985), IRAS 15091−2107 is classified as a type 1 Seyfert, notwithstanding that the H i emission lines are only slightly broader than the forbidden lines and Fe ii emission is as strong as observed in NLSy1 galaxies.…”

Evidence of powerful relativistic jets in narrow-line Seyfert 1 galaxies

“…Now, in order to make a more extended work, I have relaxed the prescription on R and added also less radio-loud and even radio-quiet (although not silent) NLS1s from the FIRST Bright Quasars Survey (FBQS) [101]. Therefore, the sample studied in the present work is composed of 76 NLS1s, of which 45 are from the FBQS [101], 23 are from the SDSS [104] and 8 are from literature [41,65,84,105,107] (see Tables A1 and A2 in the Appendix). The radio-quiet (R < 10) subsample is composed of 30 sources, while the radio-loud one (R > 20) has 39 objects; 7 NLS1s of the present list are radio-intermediate (10 < R < 20).…”

“…1. The measurements of the FWHM Hβ are taken from the available literature ( [41,65,84,101,104,105,107]). …”