“Constraints on the active galactic nucleus and starburst activity of local ultraluminous infrared galaxies from a broad range of torus models”

Published in Monthly Notices of the Royal Astronomical Society

Posted on February 21, 2025

I am pleased to share our research article “Constraints on the active galactic nucleus and starburst activity of local ultraluminous infrared galaxies from a broad range of torus models”, published in Monthly Notices of the Royal Astronomical Society.

In this paper we further explore the properties of the HERschel Ultra Luminous Infrared Galaxy Survey (HERUS) sample of 42 local ultraluminous infrared galaxies (ULIRGs) with SMART. We fit the spectral energy distributions of the HERUS ULIRGs with four different models for the active galactic nucleus (AGN) torus, a starburst and a spheroidal galaxy model, to put constraints on the AGN fraction of the galaxies and their star formation rate (SFR). Two of the AGN torus models we explored are smooth and two are two-phase. We find that, in most cases, a smooth tapered AGN torus provides the best fit to the data. We also find that solutions with other torus models may predict AGN and total luminosities up to an order of magnitude or more lower, but very rarely higher than the best-fitting model. In contrast, we find that, with minor exceptions, the predicted SFR and stellar mass of the ULIRGs are generally robustly estimated irrespective of the assumed torus model. For more details, please read the article.

For this work we acknowledge support from the projects CYGNUS and CYGNUS+ funded by the European Space Agency.