Absence of nuclear polycyclic aromatic hydrocarbon emission from a compact starburst: The case of the type-2 quasar Mrk 477

Ramos Almeida, C.; Esparza-Arredondo, D.; González-Martín, O.; García-Bernete, I.; Pereira-Santaella, M.; Alonso-Herrero, A.; Acosta-Pulido, J. A.; Bessiere, P. S.; Levenson, N. A.; Tadhunter, C. N.; Rigopoulou, D.; Martínez-Paredes, M.; Cazzoli, S.; García-Lorenzo, B.
Bibliographical reference

Astronomy and Astrophysics

Advertised on:
1
2023
Number of authors
14
IAC number of authors
5
Citations
2
Refereed citations
2
Description
Mrk 477 is the closest type-2 quasar, at a distance of 163 Mpc. This makes it an ideal laboratory for studying the interplay between nuclear activity and star formation with a great level of detail and signal-to-noise. In this Letter we present new mid-infrared (mid-IR) imaging and spectroscopic data with an angular resolution of 0.4″ (∼300 pc) obtained with the Gran Telescopio Canarias instrument CanariCam. The N-band (8-13 μm) spectrum of the central ∼400 pc of the galaxy reveals [S IV]λ10.51 μm emission, but no 8.6 or 11.3 μm polycyclic aromatic hydrocarbon (PAH) features, which are commonly used as tracers of recent star formation. This is in stark contrast with the presence of a nuclear starburst of ∼300 pc in size, an age of 6 Myr, and a mass of 1.1×108 M⊙, as constrained from ultraviolet Hubble Space Telescope observations. Considering this, we argue that even the more resilient, neutral molecules that mainly produce the 11.3 μm PAH band are most likely being destroyed in the vicinity of the active nucleus despite the relatively large X-ray column density, log NH = 23.5 cm−2, and modest X-ray luminosity, 1.5×1043 erg s−1. This highlights the importance of being cautious when using PAH features as star formation tracers in the central region of galaxies to evaluate the impact of feedback from active galactic nuclei.
Related projects
Supermassive black holes modify the distribution of molecular gas in the central regions of galaxies. Credit: HST and C. Ramos Almeida.
Nuclear Activity in Galaxies: a 3D Perspective from the Nucleus to the Outskirts

This project consists of two main research lines. First, the study of quasar-driven outflows in luminous and nearby obscured active galactic nuclei (AGN) and the impact that they have on their massive host galaxies (AGN feedback). To do so, we have obtained Gran Telescopio CANARIAS (GTC) infrared and optical observations with the instruments

Cristina
Ramos Almeida