BeppoSAX observations of Narrow-Line Seyfert 1 galaxies:I. Ton S 180

TL;DR

This study presents the first BeppoSAX X-ray spectrum of the NLS1 galaxy Ton S 180, revealing a steep power-law and highly ionized iron line, supporting high accretion rates as a key NLS1 characteristic.

Contribution

First X-ray spectrum of Ton S 180 with BeppoSAX, linking steep spectra and ionized iron to high accretion rates in NLS1 galaxies.

Findings

X-ray spectrum shows steep power law with Gamma=2.3

Detection of highly ionized iron line

Supports high accretion rate as key NLS1 feature

Abstract

We report on the first spectrum up to 10 keV of the bright narrow-line Seyfert 1 galaxy Ton S 180, obtained with the imaging instruments onboard BeppoSAX. This is the first observed source in a sample of a dozen narrow-line Seyfert 1 galaxies in the BeppoSAX Core Program. We also present and discuss a high quality optical spectrum taken at the 1.5 m telescope at La Silla two months before the BeppoSAX observation. The X-ray spectrum shows a clear hardening above about 2 keV, where a power law with Gamma = 2.3 plus an iron line provide a good description of the data. This slope is significantly steeper than the typical one for classical Seyfert 1's and quasars. The best fit line energy is suggestive of highly ionized iron, which would support the idea that the high accretion rate is (one of) the fundamental parameter(s) characterizing the Narrow Line Seyfert 1 phenomenon.