Kavli Affiliate: Roberto Maiolino
| First 5 Authors: Michele Perna, Santiago Arribas, Isabella Lamperti, Chiara Circosta, Elena Bertola
| Summary:
Merger events can trigger gas accretion onto supermassive black holes (SMBHs)
located at the centre of galaxies, and form close pairs of AGN. The fraction of
AGN in pairs offers critical insights into the dynamics of galaxy interactions,
SMBH growth, and their co-evolution with host galaxies. However, the
identification of dual AGN is difficult, as it requires high-quality spatial
and spectral data; hence, only very few pairs have been found in the distant
Universe so far. This study aims to provide a first observational estimate of
the fraction of dual AGN at 2<z<6 by analysing a sample of 16 AGN observed with
JWST/NIRSpec IFS, as part of the GA-NIFS survey. For two AGN in our sample, we
also incorporate archival VLT/MUSE data to expand the search area. We searched
for nearby companion galaxies and emission-line sources within the ~20×20 kpc
field of view of the NIRSpec data cubes, extending up to ~50 kpc using the MUSE
data cubes. We analysed the spectra of such emitters to determine their
physical and kinematic properties. We report the serendipitous discovery of a
triple AGN and four dual AGN (two of which considered as candidates), with
projected separations in the range 3-28 kpc. Their AGN classification is mainly
based on standard optical emission line flux ratios, as observed with
JWST/NIRSpec, and is complemented with additional multi-wavelength diagnostics.
The identification of these 3-5 multiple AGN out of the 16 AGN systems in
GA-NIFS (i.e. ~20-30%) suggests they might be more common than previously
thought based on other observational campaigns. Moreover, our inferred fraction
of dual AGN moderately exceeds predictions from cosmological simulations that
mimic our observational criteria (~10%). This work highlights the exceptional
capabilities of NIRSpec for detecting distant dual AGN, and prompts new
investigations to constrain their fraction across cosmic time.
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