Special Astrophysics Seminar

Ubiquitous (and Obscured) Nuclear Activity in Star-Forming Galaxies

Stephanie Juneau

CEA-Saclay

While it is clear that gas fuels both star formation and nuclear activity in galaxies, the connection between the growth of their stellar content and that of their central supermassive black hole remains elusive. What are the governing physical processes? Do the stars and central black hole grow in lock-step? Using multi-wavelength tracers on a sample of actively star-forming galaxies at intermediate redshifts (0.3<z<1), we show that active galactic nuclei (AGN) are more ubiquitous than what previous studies have found, and that a large fraction of black hole growth takes place in an X-ray obscured phase. Our results furthermore suggest that AGN X-ray obscuration is related to the gas content of the host galaxies, linking fueling at small scales to obscuration at a range of physical scales. Another important implication is that X-ray selected AGN studies may miss an important phase of black hole growth and provide us with an incomplete view of the connection between AGN with their host galaxies. Will we witness a shift in paradigm regarding the connection between galaxies and their central black hole?