Astronomical First: Differences Detected Between Discs of Active and Non-Active Galaxies - SciTechDaily

A study led by researchers at the Instituto de Astrofísica de Canarias (IAC), making comparison between the discs of several pairs of spiral galaxies, active and non-active, concludes that in the discs of the former the rotational motion of the stars is of greater importance.

This study, just accepted for publication in Astronomy & Astrophysics Letters, is the first evidence for large scale dynamical differences between active and non-active galaxies in the local universe.

The astronomers participating are from the Instituto de Astrofísica de Canarias (IAC) and the University of La Laguna (ULL); as well as the NatiAstronomical First: Differences Detected Between Discs of Active and Non-active Galaxiesonal Autonomous University of Mexico (UNAM), the Complutense University of Madrid (UCM) and the Instituto de Astrofísica de Andalucia (IAA).

In those cases we say that the galaxy has an active nucleus (AGN).

The material which feeds the AGN must initially be quite distant from the nucleus, in the disc of the galaxy, rotating around its center.

Image illustrating the comparison between an active spiral galaxy (orange box) and its non-active twin (blue box).

“Studying the mechanisms which control the relation between the active nucleus and the rest of the galaxy -explains Ignacio del Moral Castro, a doctoral student in the IAC and the University of La Laguna (ULL) and first author of the article- is necessary to understand how these objects form and evolve, and to be able to throw light on this question we need to compare active and non-active galaxies.

Previously, in the majority of studies the procedure used was the identification of a sample of active galaxies within a large survey, which were then compared to the rest of the galaxies in the survey having similar properties that do not show nuclear activity.

Firstly, they identified active spiral galaxies in the CALIFA sample, and for each of them they looked for a non-active galaxy which had equivalent global properties, i.e.

Using this method the team put forward two scenarios to explain the dynamical differences between active and non-active galaxies.

“The result surprised us; we really didn’t expect to find this type of differences on a large scale, give that the duration of the active phase is very short in comparison with the lifetime of a galaxy, and with the time needed to produce morphological and dynamical changes,” says Begoña García Lorenzo, and IAC researcher, and a coauthor of the article.

Reference: “Larger λR in the disc of isolated active spiral galaxies than in their non-active twins” by I.

August 2, 2020

August 2, 2020

August 2, 2020

August 2, 2020