Fast Ionized Outflows Detected in Candidate Dual AGN System MCG-03-34-64
Astronomers using the VLT/ERIS instrument have detected two fast ionised gas outflows in the nearby Seyfert galaxy MCG-03-34-64, a candidate system hosting two active galactic nuclei separated by only ~100 parsecs. The outflows reach maximum velocities of approximately -1700 km/s and show unusually low dust content compared to the surrounding interstellar medium, with each outflow carrying roughly 20 solar masses of gas per year. The findings are consistent with a dual AGN scenario but cannot yet confirm it, highlighting the need for further observations of these rare close-separation systems.
Using the VLT/ERIS integral field unit in J-band, researchers observed MCG-03-34-64, a nearby galaxy at redshift z = 0.0167 that is a candidate host of two active galactic nuclei separated by roughly 100 parsecs. Two spatially distinct regions of highly broadened emission (W80 ~ 1500 km/s) were identified, coinciding with the positions of the two candidate nuclei, and interpreted as fast ionised gas outflows with maximum blueshifted velocities of about -1700 km/s — among the highest 2–5 percentile of local AGN with comparable bolometric luminosities. Each outflow carries an ionised gas mass of approximately (4 ± 1) × 10⁵ solar masses and a mass outflow rate of 20 ± 5 solar masses per year, making them broadly comparable to one another. Analysis of archival VLT/X-shooter spectra revealed that the coronal [Fe VII] 6087 Å line is detected only in the outflowing component and lacks the systemic emission seen in [Ne V] 3425 Å, which has similar ionisation potential and critical density; this is interpreted as iron depletion onto dust grains in the ambient ISM, with the outflow itself being relatively dust-poor. The two outflows could be driven by the individual nuclei or by the interaction of a radio jet with the interstellar medium, and while the overall evidence is consistent with a dual AGN interpretation, the authors stress that confirmation requires additional observations.
What's missing
The study does not yet provide independent kinematic or dynamical confirmation that the two nuclei are gravitationally bound or at the stated ~100 pc separation (e.g., via VLBI astrometry or resolved stellar kinematics), which is the key open question for confirming the dual AGN nature. The molecular/neutral gas phases of the outflows — which could dominate the total outflow energetics — are not constrained by these observations.
What different sources said
- arXiv astro-phCenter
Fast, dust-poor outflows in the local candidate dual AGN MCG-03-34-64 observed with VLT/ERIS
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