arxiv: 2503.15317 · v2 · ★pith:AGOFEBAJnew · submitted 2025-03-19 · 🌌 astro-ph.GA
Euclid Quick Data Release (Q1). First Euclid statistical study of galaxy mergers and their connection to active galactic nuclei
show 328 more authors
read the original abstract
Galaxy major mergers are a key pathway to trigger AGN. We present the first detection of major mergers in the Euclid Deep Fields and analyse their connection with AGN. We constructed a stellar-mass-complete ($M_*>10^{9.8}\,M_{\odot}$) sample of galaxies from the first quick data release (Q1), in the redshift range z=0.5-2. We selected AGN using X-ray data, optical spectroscopy, mid-infrared colours, and processing \IE observations with an image decomposition algorithm. We used CNNs trained on cosmological simulations to classify galaxies as mergers and non-mergers. We found a larger fraction of AGN in mergers compared to the non-merger controls for all AGN selections, with AGN excess factors ranging from 2 to 6. Likewise, a generally larger merger fraction ($f_{merg}$) is seen in active galaxies than in the non-active controls. We analysed $f_{merg}$ as a function of the AGN bolometric luminosity ($L_{bol}$) and the contribution of the point-source to the total galaxy light in the \IE-band ($f_{PSF}$) as a proxy for the relative AGN contribution fraction. We uncovered a rising $f_{merg}$, with increasing $f_{PSF}$ up to $f_{PSF}=0.55$, after which we observed a decreasing trend. We then derived the point-source luminosity ($L_{PSF}$) and showed that $f_{merg}$ monotonically increases as a function of $L_{PSF}$ at z<0.9, with $f_{merg}>$50% for $L_{PSF}>2\,10^{43}$ erg/s. At z>0.9, $f_{merg}$ rises as a function of $L_{PSF}$, though mergers do not dominate until $L_{PSF}=10^{45}$ erg/s. For X-ray and spectroscopic AGN, we computed $L_{bol}$, which has a positive correlation with $f_{merg}$ for X-ray AGN, while shows a less pronounced trend for spectroscopic AGN due to the smaller sample size. At $L_{bol}>10^{45}$ erg/s, AGN mostly reside in mergers. We concluded that mergers are strongly linked to the most powerful, dust-obscured AGN, associated with rapid supermassive black hole growth.
This paper has not been read by Pith yet.
Forward citations
Cited by 4 Pith papers
Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.
-
Only obscured yet luminous active galactic nuclei are closely associated with galaxy mergers: Direct observational evidence from type 2 active galactic nuclei
astro-ph.GA 2026-06 unverdicted novelty 6.0
Only luminous and heavily obscured type 2 AGNs show high merger fractions (~0.7), unlike low-luminosity or low-obscuration ones (~0.2).
-
Galaxy discs regulate the growth of supermassive black holes
astro-ph.GA 2026-04 unverdicted novelty 5.0
Disc galaxies inhibit supermassive black hole growth by preserving rotational support in central gas, while mergers in ellipticals disrupt this support and enable rapid accretion.
-
Towards a consistent framework of determining active galactic nucleus contribution fraction and host galaxy properties
astro-ph.GA 2026-06 unverdicted novelty 4.0
A framework using CIGALE and GRAHSP SED fitting plus deep-learning imaging is applied to COSMOS-Web galaxies to estimate AGN fractions in the F150W band and compare methods, revealing degeneracies.
-
Unlocking the Full Potential of SKAO Extra-galactic Science with High-multiplex Optical Spectroscopy
astro-ph.GA 2026-06 unverdicted novelty 2.0
Optical spectroscopy is required to unlock the full potential of SKAO extragalactic surveys through precise redshifts, activity diagnostics, HI stacking, and large-scale structure mapping.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.