A comparative analysis of the active galactic nucleus and star formation characteristics of broad- and narrow-line Seyfert 1 galaxies^⋆

¹ Indian Institute of Astrophysics, Block II, Koramangala, Bangalore, India
e-mail: stalin@iiap.res.in
² Pondicherry University, Puducherry 605014, India
³ Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263002, India
⁴ Instituto de Fisica de Cantabria (CSIC-Universidad de Cantabria), Avenida de los Castros, 39005 Santander, Spain
⁵ Astronomisches Rechen-Institut, Zentrum fur Astronomie der Universitat Heidelberg, Monchhofstr. 12-14, 69120 Heidelberg, Germany
⁶ European Space Agency (ESA), European Space Astronomy Centre (ESAC), Camino Bajo del Castillo s/n, 28692 Villanueva de la Canada, Madrid, Spain

Received: 26 February 2023
Accepted: 4 March 2024

Abstract

We report here our comparative analysis of the active galactic nucleus (AGN) and star formation (SF) characteristics of a sample of narrow-line Seyfert 1 (NLS1) and broad-line Seyfert 1 (BLS1) galaxies. Our sample consisted of 373 BLS1 and 240 NLS1 galaxies and spanned the redshift 0.02 < z < 0.8. The broad-band spectral energy distribution, constructed using data from the ultra-violet to the far-infrared, was modelled using CIGALE to derive the basic properties of our sample. We searched for differences in stellar mass (M_*), star formation rate (SFR), and AGN luminosity (L_AGN) in the two populations. We also estimated new radiation-pressure-corrected black hole masses for our sample of BLS1 and NLS1 galaxies. While the virial black hole mass (M_BH) of BLS1 galaxies is similar to their radiation-pressure-corrected M_BH values, the virial M_BH values of NLS1 galaxies are underestimated. We found that NLS1 galaxies have a lower M_BH of log (M_BH [M_⊙]) = 7.45 ± 0.27 and a higher Eddington ratio of log (λ_Edd) = −0.72 ± 0.22 than BLS1 galaxies, which have log (M_BH [M_⊙]) and λ_Edd values of 8.04 ± 0.26 and −1.08 ± 0.24, respectively. The distributions of M_*, SFR, and specific star formation (sSFR = SFR/M_*) for the two populations are indistinguishable. This analysis is based on an independent approach and contradicts reports in the literature that NLS1 galaxies have a higher SF than BLS1 galaxies. While we found that L_AGN increases with M_*, L_SF flattens at high M_* for both BLS1 and NLS1 galaxies. The reason may be that SF is suppressed by AGN feedback at M_* higher than ∼10¹¹ M_⊙ or that the AGN fuelling mechanism is decoupled from SF. Separating the sample into radio-detected and radio-undetected subsamples, we found no difference in their SF properties suggesting that the effect of AGN jets on SF is negligible.