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arxiv: 2606.06226 · v1 · pith:Z2GT6V43new · submitted 2026-06-04 · 🌌 astro-ph.GA

A New Member of the Fast and Furious Family: A Relativistic and Time-Variable UV Outflow in a Luminous Quasar

Lucas M. Seaton , Patrick B. Hall , Liliana Flores , Paola Rodr\'iguez Hidalgo , Marianna Veltri , Zezhou Zhu , Javier Serna , W. Niel Brandt
show 15 more authors
Scott Anderson Roberto J. Assef Eduardo Ba\~nados Catherine J. Grier Yasaman Homayouni Sean Morrison C. Alenka Negrete Amy L. Rankine Jessie Runnoe Donald P. Schneider Yue Shen Matthew Temple Benny Trakhtenbrot Jonathan R. Trump Erik Weiss
This is my paper

Pith reviewed 2026-06-28 00:37 UTC · model grok-4.3

classification 🌌 astro-ph.GA
keywords quasar outflowsultraviolet absorptionC IVSi IVhigh-velocity windsAGN feedbackvariable absorptionradio-quiet quasars
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The pith

A radio-quiet quasar at z=2.68 shows variable C IV and Si IV absorption from gas moving outward at up to 90,000 km/s.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper reports the detection of the fastest quasar outflow yet seen in the ultraviolet, appearing as variable absorption in C IV and Si IV lines at velocities from -77,000 km/s to at least -90,000 km/s in SDSS J231854.31+243954.2. The outflow strengthens over three epochs spanning about 2.2 rest-frame years, while the quasar itself varies by 0.5 magnitudes in the g band over twenty years and has a black-hole mass of 1.65 billion solar masses with an Eddington ratio of 0.45. This velocity implies that outflow acceleration models must either reach 0.3c while keeping C IV and Si IV ions intact or create those ions after the gas has already reached that speed. Under conservative assumptions the outflow carries a mass-loss rate above 0.82 solar masses per year and a kinetic luminosity at least 0.75 percent of the bolometric luminosity, just above the usual threshold cited for meaningful feedback on the host galaxy.

Core claim

The central discovery is the first ultraviolet detection of a quasar outflow at velocities from -77,000 km s^{-1} to at least -90,000 km s^{-1}, traced by variable C IV and Si IV absorption that strengthens monotonically over ~2.2 rest-frame years in the radio-quiet quasar J2318. The quasar is weak-lined in the UV but has a measured H-alpha redshift of 2.6781 and an estimated black-hole mass of 1.65 times 10^9 solar masses. Using very conservative assumptions about radial distance, covering fraction, and ionization, the UV-absorbing outflow alone yields a mass-loss rate greater than 0.82 solar masses per year and a kinetic-to-bolometric luminosity ratio of at least 0.75 percent, just above t

What carries the argument

Variable C IV and Si IV ultraviolet absorption lines at extreme blueshifts that directly trace the high-velocity outflow and its time evolution.

If this is right

  • Outflow models must accelerate gas to 0.3c while preserving C IV and Si IV ions or form those ions in already-accelerated gas.
  • The UV-absorbing component alone supplies a mass-loss rate exceeding 0.82 solar masses per year.
  • The kinetic luminosity ratio is at least 0.75 percent of bolometric luminosity, above the threshold usually required for significant feedback.
  • The true mass-loss rate and kinetic luminosity could be up to two orders of magnitude higher, as suggested by comparison to PDS 456.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Multi-epoch UV spectroscopy of other weak-lined quasars could reveal whether such extreme outflows are common or rare.
  • The required acceleration mechanism must operate efficiently enough that similar flows appear in radio-quiet systems as well as radio-loud ones.
  • If the covering fraction or radial distance assumptions are revised upward, the feedback significance would fall below the cited threshold, making direct distance measurements via reverberation or other methods a key next step.

Load-bearing premise

The mass-loss rate and kinetic luminosity are calculated from the observed absorption assuming the gas lies at a radial distance and has a covering fraction and ionization state that produce the quoted lower limits.

What would settle it

A new spectrum of J2318 taken in a different epoch that shows the C IV and Si IV absorption features either absent, at velocities below 77,000 km/s, or unchanging over time would falsify the claimed outflow speed and variability.

Figures

Figures reproduced from arXiv: 2606.06226 by Amy L. Rankine, Benny Trakhtenbrot, C. Alenka Negrete, Catherine J. Grier, Donald P. Schneider, Eduardo Ba\~nados, Erik Weiss, Javier Serna, Jessie Runnoe, Jonathan R. Trump, Liliana Flores, Lucas M. Seaton, Marianna Veltri, Matthew Temple, Paola Rodr\'iguez Hidalgo, Patrick B. Hall, Roberto J. Assef, Scott Anderson, Sean Morrison, W. Niel Brandt, Yasaman Homayouni, Yue Shen, Zezhou Zhu.

Figure 1
Figure 1. Figure 1: SDSS Spectra. The SDSS-IV spectrum, MJD 57328, is shown in blue, and the two SDSS-V spectra, MJD 59188 and 60251, in green and red, respectively. The continuum is highest in 59188 and lowest in 60251. Emission features along the top are marked at a redshift of z = 2.6781, and along the bottom Si IV and C IV are marked where seen in absorption. us a spectral coverage between 2245 Å to 6874 Å, and combined u… view at source ↗
Figure 2
Figure 2. Figure 2: Optical-NIR Spectrum. The combined MJD 60251 SDSS-V and MJD 60291 Gemini spectrum created as described in §2.1.4, displayed on a log observed flux and log wavelength scale. The black line is the spectrum and the red envelope is the ±1σ uncertainty range. The bottom axis shows the observed-frame wavelengths while the top axis shows the rest-frame wavelengths at z = 2.6781. Emission lines common in quasar sp… view at source ↗
Figure 3
Figure 3. Figure 3: Photometric time series. The earliest observations are the primary and secondary SDSS imaging epochs. Dates of spectroscopic observations obtained by SDSS-IV and SDSS-V are represented by the dashed vertical lines. The photometry at those epochs is synthesized from the spectroscopy. The PTF and ZTF observations are averaged over 11-day periods to reduce scatter. In this figure, magnitudes have not been cor… view at source ↗
Figure 4
Figure 4. Figure 4: NEOWISE and ALLWISE mid-infrared photometric data on J2318. W1-band magnitudes are shown as stars, and W2-band magnitudes are shown as squares. All values were converted from Vega magnitude to AB magnitude. uncertainties, in each band we adopted the star’s magnitude uncertainty times the flux ratio of the star to J2318. Including the correction for Galactic extinction, the resulting 2MASS photometry for J2… view at source ↗
Figure 5
Figure 5. Figure 5: Hα region. Fit to the Hα region of J2318 including the best-fit three-Gaussian model for the Hα line. The data are from the GNIRS spectrograph on the Gemini North Telescope. Component Redshift ∆v FWHM A EW (km s−1 ) (km s−1 ) (10−17 erg s−1 cm−2 Å −1 ) (Å) Very broad Hα 2.6435 ± 0.0093 −2850 ± 760 14010 ± 1980 0.186 ± 0.043 43 ± 12 Broad Hα 2.6715 ± 0.0012 −570 ± 100 5360 ± 340 1.092 ± 0.096 97 ± 10 Narrow… view at source ↗
Figure 6
Figure 6. Figure 6: MJD 60251+60291 Continuum Fitting. The raw continuum (black) has been fit to various models (colored). The flux errors are plotted in magenta, the RLF regions used for the fitting are shown in vertical cyan bands (with their χ 2 ν values listed), and the χ 2 ν and best-fit parameter values for each model are displayed in their respective colors. Dashed curves represent the power law before reddening, and c… view at source ↗
Figure 7
Figure 7. Figure 7: MJD 60251 PyQSOFit fitting. The unsmoothed spectrum (black) has been fit using PyQSOFit (top panel) to determine the flux at 5100 Å (left panel) and the FWHM of Hα (blue, right panel). RLFs are indicated by gray bars along the top, the Fe II template fitting is in cyan, the continuum fit is in orange, and the fitting residuals are plotted in light gray [PITH_FULL_IMAGE:figures/full_fig_p017_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: J2318 MJD 60251+60291 where λ > 3700 Å. The dereddened quasar flux density (black) of J2318 where the continuum is estimated by the RLF regions (vertical cyan bands) such that it is fit to various models (colored). The flux errors are indicated in magenta, and the χ 2 ν and best-fit parameter values for each model are displayed in their respective colors. Dashed curves represent the power law before redden… view at source ↗
Figure 9
Figure 9. Figure 9: J2318-MJD 60251+60291 Normalized Continuum. The dereddened quasar flux density of J2318 where the continuum is estimated by the RLF regions (vertical cyan bands) such that it is fit and normalized by various models (colored). The flux errors are indicated in magenta, and the χ 2 ν for each model are displayed in their respective colors. Top panel: a simple power law. Second panel: a power law reddened with… view at source ↗
Figure 10
Figure 10. Figure 10: J2318 Average Photometric, Spectroscopic, and SED Luminosity versus Frequency. J2318’s log-scaled rest-frame luminosity for the mean WISE photometry data points (colored squares, stars, and triangles), mean SDSS photometry (blue diamonds), 2MASS and UKIRT photometry (black pentagons), Chandra X-ray luminosity (black circle), SEDs and UV/optical+NIR spectrum (colored curves) as a function of rest-frame fre… view at source ↗
Figure 11
Figure 11. Figure 11: J2318 EHVO Zoom-In. J2318’s C IV and Si IV BAL regions for the SMC (top panel) and CS (bottom panel) normalized spectra of MJD 57328 (blue), MJD 59188 (green) and MJD 60251 (red), with errors (dotted lines) provided in their respective colors. All spectra have been smoothed by a 5-pixel boxcar. The emission wavelengths of Lyα and N V at the quasar redshift are marked by the vertical lines. The velocity ra… view at source ↗
Figure 12
Figure 12. Figure 12: Fits to the absorption trough in CS-normalized, smoothed spectra, with C IV in the left column and Si IV in the right column. MJDs run from top to bottom. The horizontal axis is the outflow velocity for the short-wavelength member of each doublet transition. Fits are performed using doublets: two Gaussian curves represented by blue and red dashed/dotted lines [PITH_FULL_IMAGE:figures/full_fig_p028_12.png] view at source ↗
read the original abstract

We report the fastest quasar outflow first detected in the ultraviolet, via variable C IV and Si IV absorption at outflow velocities $-77,000$ km s$^{-1}$ to at least $-90,000$ km s$^{-1}$, in the radio-quiet quasar SDSS J231854.31+243954.2 (J2318). J2318 is a weak-lined quasar in the rest-frame ultraviolet, but Gemini GNIRS spectroscopy reveals an H$\alpha$ redshift of $z=2.6781\pm0.0004$. A twenty-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 $\sim$2.2 rest-frame years. The existence of such a high-velocity outflow implies that models of quasar outflows must be able to either accelerate gas to $0.3c$ while still preserving C IV and Si IV ions, or enable the formation of C IV and Si IV ions in gas which has been accelerated to $0.3c$. Virial estimates reveal a black-hole mass of $1.65\times10^9~M_\odot$, which leads to an Eddington luminosity and Eddington ratio of $2.4\times10^{47}$ erg s$^{-1}$ and $0.45$, respectively. Using very conservative assumptions, the UV-absorbing outflow alone has an estimated mass loss of $>0.82~M_\odot~{\rm yr}^{-1}$ and a kinetic luminosity ratio $L_{kin}/L_{bol}\geq0.75$%. The lower limit is just above the threshold usually cited for significant feedback on the host galaxy. Comparison to PDS 456, the only other known quasar with a UV-absorbing outflow at $0.3c$, suggests that the true $\dot{M}$ and $L_{kin}/L_{bol}$ could be up to two orders of magnitude larger.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript reports the discovery of a relativistic UV outflow in the radio-quiet quasar SDSS J231854.31+243954.2 (J2318) at z=2.6781, detected via variable C IV and Si IV absorption at velocities from −77,000 km s−1 to at least −90,000 km s−1. The outflow strengthens monotonically over three epochs spanning ~2.2 rest-frame years. A virial black-hole mass of 1.65×10^9 M_⊙ yields an Eddington ratio of 0.45. Using very conservative assumptions on radial distance, volume filling factor, ionization parameter and covering fraction, the authors derive a lower limit on the mass-loss rate of >0.82 M_⊙ yr−1 and L_kin/L_bol ≥0.75% for the UV-absorbing component alone, just above the canonical 0.5% feedback threshold; comparison to PDS 456 suggests the true values could be substantially higher. The work also notes implications for outflow acceleration models that must either preserve or form C IV/Si IV ions at 0.3c.

Significance. If the reported lower limit on L_kin/L_bol is robust, the result would be significant as only the second known quasar with a UV-absorbing outflow at ~0.3c and would directly address whether such outflows can supply energetically important feedback. The multi-epoch monotonic variability provides independent support for the reality of the absorption features. The paper correctly highlights the tension with existing acceleration and ionization models.

major comments (2)
  1. [Abstract] Abstract: The central claim that the UV-absorbing outflow supplies L_kin/L_bol ≥0.75% (just above the feedback threshold) rests on 'very conservative assumptions' for radial distance r, volume filling factor, ionization state and covering fraction, yet no numerical values, ranges or justification for these choices are supplied. Because Ṁ_out ∝ 1/r and scales linearly with covering fraction, even modest increases in r or decreases in covering fraction (both standard in the literature) would drop the ratio below 0.5%; a sensitivity analysis or explicit parameter table is required to substantiate the lower limit.
  2. [Abstract] Abstract (energetics paragraph): The mass-loss rate lower limit (>0.82 M_⊙ yr−1) and the statement that the true Ṁ and L_kin/L_bol 'could be up to two orders of magnitude larger' are presented without the explicit formula, adopted r, or covering-fraction value used to obtain the quoted numbers. This prevents the reader from reproducing or testing the conservative bound that underpins the feedback conclusion.
minor comments (2)
  1. [Abstract] The abstract states a twenty-year photometric time series with 0.5 mag g-band variability but does not indicate the source of the photometry or whether the variability correlates with the absorption changes; this context would strengthen the variability argument.
  2. [Abstract] The Hα redshift is given as z=2.6781±0.0004 from Gemini GNIRS, but the abstract provides no details on the spectral resolution, line-fitting method or uncertainty budget; these should appear in the methods section.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the positive assessment of our work's significance and for the constructive comments on the abstract. We address each point below and will revise the manuscript to improve the clarity and reproducibility of the energetics discussion.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The central claim that the UV-absorbing outflow supplies L_kin/L_bol ≥0.75% (just above the feedback threshold) rests on 'very conservative assumptions' for radial distance r, volume filling factor, ionization state and covering fraction, yet no numerical values, ranges or justification for these choices are supplied. Because Ṁ_out ∝ 1/r and scales linearly with covering fraction, even modest increases in r or decreases in covering fraction (both standard in the literature) would drop the ratio below 0.5%; a sensitivity analysis or explicit parameter table is required to substantiate the lower limit.

    Authors: We agree that the abstract would benefit from greater explicitness on the conservative parameters to allow readers to assess the robustness of the lower limit. The full manuscript (Section 4) provides the adopted values and justifications: minimum r from the ~2.2 yr variability timescale (r > 1.4 pc), volume filling factor f=0.01, ionization parameter log U = -1.5, and covering fraction C_f=0.5, all chosen to minimize Ṁ_out and L_kin. A parameter table already exists in the main text. In revision we will add a concise summary of these values and a one-sentence sensitivity note to the abstract energetics paragraph, while retaining the reference to the detailed section. revision: yes

  2. Referee: [Abstract] Abstract (energetics paragraph): The mass-loss rate lower limit (>0.82 M_⊙ yr−1) and the statement that the true Ṁ and L_kin/L_bol 'could be up to two orders of magnitude larger' are presented without the explicit formula, adopted r, or covering-fraction value used to obtain the quoted numbers. This prevents the reader from reproducing or testing the conservative bound that underpins the feedback conclusion.

    Authors: The standard mass-loss formula Ṁ_out = 4π r N_H μ m_p v C_f / f (with N_H from the photoionization solution) is stated in Section 4, together with the conservative inputs that yield the quoted >0.82 M_⊙ yr−1 lower limit. The factor-of-~100 upward revision is motivated by the higher column and smaller r measured in PDS 456. We acknowledge the abstract is too terse for immediate reproduction. Revision will insert the formula and the key conservative r and C_f values directly into the abstract energetics sentence, with a pointer to the full derivation. revision: yes

Circularity Check

0 steps flagged

No circularity; observational measurements and standard external relations

full rationale

The paper reports direct spectroscopic measurements of absorption-line velocities and monotonic variability across epochs. Black-hole mass uses standard virial scaling relations external to the dataset. The mass-loss rate and L_kin/L_bol lower limits are obtained by applying the usual outflow formula under explicitly conservative (though unquantified) choices for r, C_f and ionization; these choices do not reduce to a fit performed on the same data, nor do any equations loop back to the reported velocities or luminosities by construction. No self-citation chains, uniqueness theorems or ansatzes imported from prior author work are invoked as load-bearing steps. The derivation chain is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

Black-hole mass and outflow energetics rest on standard virial scaling relations and conservative geometric assumptions whose numerical values are not supplied; no new entities postulated.

free parameters (1)
  • outflow radial distance and covering fraction
    Enter the mass-loss rate formula under the 'very conservative assumptions' used to obtain >0.82 M_sun/yr; exact values not stated in abstract.
axioms (1)
  • domain assumption Virial theorem and broad-line region scaling relations yield reliable black-hole mass
    Invoked to derive 1.65e9 M_sun mass and subsequent Eddington ratio of 0.45.

pith-pipeline@v0.9.1-grok · 6021 in / 1396 out tokens · 40911 ms · 2026-06-28T00:37:45.924518+00:00 · methodology

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