Martínez Paredes, M., Aretxaga, I., González Martín, O., Alonso Herrero, A., Levenson, N. A., Almeida, C. R., López Rodríguez, E. 2019. Quantifying Star Formation Activity in the Inner 1 kpc of Local MIR Bright QSOs. Astrophysical Journal 871, 2, DOI: 10.3847/1538-4357/aafa18
We examine star formation activity in a distant (z < 0.1) and flux-limited sample of quasars (QSOs). Midinfrared (MIR) spectral diagnostics at high spatial resolution (similar to 0.4 arcsec) yield star formation rates (SFRs) in the inner regions (similar to 300 pc-1 kpc) for 13 of 20 of the sample members. We group these objects according to the size probed by the high angular resolution spectroscopy, with characteristic scales of <0.7 and similar to 0.7-1 kpc. Using the polycyclic aromatic hydrocarbon (PAH) feature at 11.3 mu m, we measure SFRs around 0.2 and 1.6 M-circle dot yr(-1). We also measure the larger aperture PAH-derived SFRs in the individual IRS/Spitzer spectra of the sample and obtain a clear detection in similar to 58% of them. We compare smaller and larger aperture measurements and find that they are similar, suggesting that star formation activity in these QSOs is more centrally concentrated, with the inner region (less than or similar to 1 kpc) accounting for the majority of star formation measured on these scales, and that PAH molecules can be present in most local MIR-bright QSOs within a few hundred parsecs from the central engine. By comparison with merger simulations, we find that our estimation of the SFR and black hole (BH) accretion rates are consistent with a scenario in which the star formation activity is centrally peaked as predicted by simulations.