Disentangling the near-infrared continuum spectral components of the inner 500 pc of Mrk 573 : two-dimensional maps

Abstract

We present a near-infrared (near-IR) study of the spectral components of the continuum in the inner 500×500 pc2 of the nearby Seyfert galaxy Mrk 573 using adaptive optics near-IR integral field spectroscopy with the instrument near-infrared integral field spectrograph of the Gemini North Telescope at a spatial resolution of ∼50 pc. We performed spectral synthesis using the STARLIGHT code and constructed maps for the contributions of different age components of the stellar population: young (age ≤100 Myr), young–intermediate (100 < age≤ 700 Myr), intermediate–old (700 Myr < age ≤ 2 Gyr) and old (age > 2 Gyr) to the near-IR K-band continuum, as well as their contribution to the total stellar mass. We found that the old stellar population is dominant within the inner 250 pc, while the intermediate-age components dominate the continuum at larger distances. A young stellar component contributes up to ∼20 per cent within the inner ∼70 pc, while hot dust emission and featureless continuum components are also necessary to fit the nuclear spectrum, contributing up to 20 per cent of the K-band flux there. The radial distribution of the different age components in the inner kiloparsec of Mrk 573 is similar to those obtained by our group for the Seyfert galaxies Mrk 1066, Mrk 1157 and NGC 1068 in previous works using a similar methodology. Young stellar populations (≤100 Myr) are seen in the inner 200–300 pc for all galaxies contributing with ≥20 per cent of the K-band flux, while the near-IR continuum is dominated by the contribution of intermediate-age stars (t = 100 Myr–2 Gyr) at larger distances. Older stellar populations dominate in the inner 250 pc.