# Quasar J2318 shows a UV-absorbing outflow at 0.3 c, the fastest first detected in ultraviolet

- Published: 2026-11-13 15:53 UTC
- Section: Sky & Space › Astronomy
- Tags: quasar J2318, fastest quasar outflow, ultraviolet absorption outflow, C IV Si IV absorption, SDSS J231854.31+243954.2, quasar wind 0.3c, Gemini GNIRS spectroscopy, black hole mass 1.65e9, AGN feedback, PDS 456
- URL: https://realtech.media/news/rt-01b0f78314d5d967bda472d2_quasar_j2318_shows/

**Astronomers detected C IV and Si IV absorption at −77,000 to −90,000 km/s in quasar SDSS J231854.31+243954.2, the fastest outflow first seen in ultraviolet.**

![Quasar J2318 shows a UV-absorbing outflow at 0.3 c, the fastest first detected in ultraviolet](https://realtech.media/media/2026/11/a1ecc87bad753c9b.jpg)
*innovanews.ru*

A team led by York University reported the fastest quasar outflow first detected in the ultraviolet, in the radio-quiet quasar SDSS J231854.31+243954.2 (J2318). According to a paper in The Astrophysical Journal, variable C IV and Si IV absorption shows gas moving at outflow velocities from −77,000 km/s to at least −90,000 km/s, about 30% of the speed of light [1]. The quasar was flagged in SDSS-V in 2023 and followed up with Gemini North.

## Source and observations

J2318 is a weak-lined quasar in the rest-frame ultraviolet. Gemini GNIRS spectroscopy gives an Hα redshift of z = 2.6781 ± 0.0004 [1]. A 20-year photometric time series shows peak-to-peak variability of 0.5 mag in the g band. The C IV outflow strengthened monotonically over three epochs spanning about 2.2 rest-frame years [1].

Virial estimates give a black-hole mass of 1.65 × 10^9 solar masses. This corresponds to an Eddington luminosity of 2.4 × 10^47 erg/s and an Eddington ratio of 0.45 [1].

## Energetics and open questions

Under very conservative assumptions, the UV-absorbing outflow alone has an estimated mass loss of more than 0.82 solar masses per year. Its kinetic luminosity ratio L_kin/L_bol is at least 0.75% [1]. The authors note that this lower limit lies just above the threshold usually cited for significant feedback on the host galaxy.

PDS 456 is the only other known quasar with a UV-absorbing outflow at 0.3 c. Comparison with it suggests, according to the authors, that the true mass loss and L_kin/L_bol could be up to two orders of magnitude larger [1].

The authors point out a constraint for quasar-wind models. They must either accelerate gas to 0.3 c while preserving C IV and Si IV ions, or allow those ions to form in gas that has already been accelerated to that speed [1]. Faster winds have been seen in X-rays, but J2318 is the fastest found in the ultraviolet, as lead author Lucas Seaton noted.

## Sources

1. [The Astrophysical Journal](https://doi.org/10.3847/1538-4357/ae5f94)
2. [innovanews.ru](https://innovanews.ru/info/news/space/kvazar-j2318-pokazal-veter-so-skorostyu-tridczat-proczentov-ot-skorosti-sveta)

---

Source: RealTech, realtech.media — https://realtech.media/news/rt-01b0f78314d5d967bda472d2_quasar_j2318_shows/