Revisiting narrow-line Seyfert 1 galaxies and their place in the Universe

High-frequency radio properties of NLS1 galaxies

11 Apr 2018, 15:30

20m

Orto Botanico di Padova

Talk

Speaker

Anne Lahteenmaki (Aalto University Metsahovi Radio Observatory & Dept of Electronics and Nanoengineering)

Description

37 GHz observations performed at Metsähovi Radio Observatory show that NLS1 galaxies are not as radio-quiet as usually presumed. The detection rate at 37 GHz is around 19%. Furthermore, high-frequency radio emission is also detected from sources classified as radio-silent; that is from sources that have no counterpart in the VLA FIRST survey at 1.4 GHz. This means that at the time of the survey, there was no active jet in the sources, and the jet was launched or activated later. We have also started to look at the radio morphologies and host galaxies of NLS1 sources to find out whether the jets are generated in spiral galaxies, or in disturbed or interacting systems. Unbiased samples of NLS1 galaxies, independent of, for example, their radio loudness parameter which is often used for searching characteristics such as gamma-ray emission, are needed to look at the population as a whole, and to arrive at meaningful conclusions of their evolution and place in the AGN zoo.