X-ray Winds In Nearby-to-distant Galaxies (X-WING) – I: Legacy Surveys of Galaxies with Ultrafast Outflows and Warm Absorbers in $z sim 0$-$4$

Kavli Affiliate: Claudio Ricci

| First 5 Authors: Satoshi Yamada, Taiki Kawamuro, Misaki Mizumoto, Claudio Ricci, Shoji Ogawa

| Summary:

As an inaugural investigation under the X-ray Winds In Nearby-to-distant
Galaxies (X-WING) program, we assembled a dataset comprising 132 active
galactic nuclei (AGNs) spanning redshifts $z sim 0$-$4$ characterized by
blueshifted absorption lines indicative of X-ray winds. Through an exhaustive
review of previous research, we compiled the outflow parameters for 573 X-ray
winds, encompassing key attributes such as outflow velocities ($V_{rm out}$),
ionization parameters ($xi$), and hydrogen column densities. By leveraging the
parameters $V_{rm out}$ and $xi$, we systematically categorized the winds
into three distinct groups: ultrafast outflows (UFOs), low-ionization parameter
(low-IP) UFOs, and warm absorbers. Strikingly, a discernible absence of linear
correlations in the outflow parameters, coupled with distributions approaching
instrumental detection limits, was observed. Another notable finding was the
identification of a velocity gap around $V_{rm out} sim 10,000~{rm
km~s^{-1}}$. This gap was particularly evident in the winds detected via
absorption lines within the $lesssim$2 keV band, indicating disparate origins
for low-IP UFOs and warm absorbers. In cases involving Fe XXV/Fe XXVI lines,
where the gap might be attributed to potential confusion between
emission/absorption lines and the Fe K-edge, the possibility of UFOs and
galactic-scale warm absorbers being disconnected is considered. An examination
of the outflow and dust sublimation radii revealed a distinction: UFOs appear
to consist of dust-free material, whereas warm absorbers likely comprise dusty
gas. From 2024, the X-Ray Imaging and Spectroscopy Mission (XRISM) is poised to
alleviate observational biases, providing insights into the authenticity of the
identified gap, a pivotal question in comprehending AGN feedback from UFOs.

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