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A new discovery space opened by eROSITA: Ionised AGN outflows from X-ray selected samples

Musiimenta, B.; Brusa, M.; Liu, T.; Salvato, M.; Buchner, J.; Igo, Z.; Waddell, S. G. H.; Toba, Y.; Arcodia, R.; Comparat, J.; Alexander, D.; Shankar, F.; Lapi, A.; Ramos Almeida, C.; Georgakakis, A.; Merloni, A.; Urrutia, T.; Li, J.; Terashima, Y.; Shen, Y.; Wu, Q.; Dwelly, T.; Nandra, K.; Wolf, J.

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B. Musiimenta

M. Brusa

Tianyu Liu
Rankings Assistant

M. Salvato

J. Buchner

Z. Igo

S. G. H. Waddell

Y. Toba

R. Arcodia

J. Comparat

F. Shankar

A. Lapi

C. Ramos Almeida

A. Georgakakis

A. Merloni

T. Urrutia

J. Li

Y. Terashima

Y. Shen

Q. Wu

T. Dwelly

K. Nandra

J. Wolf


Context. In the context of an evolutionary model, the outflow phase of an active galactic nucleus (AGN) occurs at the peak of its activity, once the central supermassive black hole (SMBH) is massive enough to generate sufficient power to counterbalance the potential well of the host galaxy. This outflow feedback phase plays a vital role in galaxy evolution.

Aims. Our aim in this paper is to apply various selection methods to isolate powerful AGNs in the feedback phase, trace and characterise outflows in these AGNs, and explore the link between AGN luminosity and outflow properties.

Methods. We applied a combination of methods to the Spectrum Roentgen Gamma (SRG) eROSITA Final Equatorial Depth survey (eFEDS) catalogue and isolated ∼1400 candidates at z > 0.5 out of ∼11 750 AGNs (∼12%). Furthermore, we narrowed down our selection to 427 sources that have 0.5 < z < 1. We tested the robustness of our selection on the small subsample of 50 sources with available good quality SDSS spectra at 0.5 < z < 1 and, for which we fitted the [OIII] emission line complex and searched for the presence of ionised gas outflow signatures.

Results. Out of the 50 good quality SDSS spectra, we identified 23 quasars (∼45%) with evidence of ionised outflows based on the presence of significant broad and/or shifted components in [OIII]λ5007 Å. They are on average more luminous (log Lbol ∼ 45.2 erg s−1) and more obscured (NH ∼ 1022 cm−2) than the parent sample of ∼427 candidates, although this may be ascribed to selection effects affecting the good quality SDSS spectra sample. By adding 118 quasars at 0.5 < z < 3.5 with evidence of outflows reported in the literature, we find a weak correlation between the maximum outflow velocity and the AGN bolometric luminosity. On the contrary, we recovered strong correlations between the mass outflow rate and outflow kinetic power with the AGN bolometric luminosity.

Conclusions. About 30% of our sample have kinetic coupling efficiencies, Ė/Lbol > 1%, suggesting that the outflows could have a significant effect on their host galaxies. We find that the majority of the outflows have momentum flux ratios lower than 20 which rules out an energy-conserving nature. Our present work points to the unequivocal existence of a rather short AGN outflow phase, paving the way towards a new avenue to dissect AGN outflows in large samples within eROSITA and beyond.


Musiimenta, B., Brusa, M., Liu, T., Salvato, M., Buchner, J., Igo, Z., …Wolf, J. (2023). A new discovery space opened by eROSITA: Ionised AGN outflows from X-ray selected samples. Astronomy & Astrophysics, 679, Article A84.

Journal Article Type Article
Acceptance Date Sep 11, 2023
Online Publication Date Nov 15, 2023
Publication Date 2023-11
Deposit Date Jan 22, 2024
Publicly Available Date Jan 22, 2024
Journal Astronomy & Astrophysics
Print ISSN 0004-6361
Electronic ISSN 1432-0746
Publisher EDP Sciences
Peer Reviewed Peer Reviewed
Volume 679
Article Number A84
Keywords Space and Planetary Science; Astronomy and Astrophysics
Public URL


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