Weekly issue

Week 9, 2025

Feb 24 – Mar 2, 2025

Week 9, 2025 includes 3 curated papers, centered on LRD, spectroscopy, high-z.

2503.00998v1

Tentative detection of neutral gas in a Little Red Dot at $z=4.46$

Hollis B. Akins, Caitlin M. Casey, John Chisholm, Danielle A. Berg, Olivia Cooper, Maximilien Franco, Seiji Fujimoto, Erini Lambrides, Arianna S. Long, Jed McKinney

Theme match 4/5

Digest

ALMA Band 3/4/5 spectroscopy targets CO(7–6) and [CI](2–1) in three Little Red Dots at z=3.10, 4.46, and 7.04, finding no CO and no far-IR continuum, implying conservative molecular gas limits ≲1–5×10^10 Msun. A2744-45924 (z=4.4655) shows a tentative 4.9σ [CI](2–1) line with a narrow FWHM ~80 km s−1. The [CI]-inferred dynamical mass is ≲10^10 Msun for conservative size assumptions, well below the local MBH–Mdyn relation and an order of magnitude under SED-based stellar mass. If confirmed, this points to LRD hosts unlike massive, gas-rich quasar hosts and lends weight to a non-stellar origin for the Balmer break.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 (CO and [CI] spectra): Check the CO(7–6) non-detections and the single [CI](2–1) feature in A2744-45924; compare line centroids to the NIRSpec/WFSS redshifts and assess per-channel noise using the grey-error tracks, including A/B image extracts for A2744-QSO1.
Figure 2 ([CI] moment-0 + spectrum): Inspect [CI] contours over the NIRCam RGB to see alignment/offset with the LRD; use the Gaussian fit and corner plot to verify the ~80 km s−1 width, integrated flux, and the 4.9σ significance given the Band 4 beam (~1.6×1.3″).
Figure 3 (MBH vs Mdyn): Locate A2744-45924 relative to local MBH–Mdyn and high-z quasar [CII]-based dynamical masses; quantify how far it lies below the local relation and compare to other JWST BLAGNs with dynamical estimates.

JWST's PEARLS: A z=6 quasar in a train-wreck galaxy merger system

Madeline A. Marshall, Rogier A. Windhorst, Giovanni Ferrami, S. P. Willner, Maria Polletta, William C. Keel, Giovanni G. Fazio, Seth H. Cohen, Timothy Carleton, Rolf A. Jansen, Rachel Honor, Rafael Ortiz, Jake Summers, Jordan C. J. D'Silva, Anton M. Koekemoer, Dan Coe, Christopher J. Conselice, Jose M. Diego, Simon P. Driver, Brenda Frye, Norman A. Grogin, Nor Pirzkal, Aaron Robotham, Russell E. Ryan,, Christopher N. A. Willmer, Haojing Yan, Massimo Ricotti, Adi Zitrin, Nathan J. Adams, Cheng Cheng, J. Stuart B. Wyithe, Jeremy Lim, Michele Perna, Hannah Übler, Chris J. Willott, Gareth Jones, Jan Scholtz, Mira Mechtley

Theme match 4/5

Digest

JWST/NIRSpec IFU prism data (0.6–5.3 μm, R≈100) on the z=5.89 quasar NDWFS J1425+3254 capture rest-UV/optical lines and spatially resolve its host environment. Broad Hα and Hβ yield MBH≈1.4×10^9 M⊙ and Lbol/LEdd≈0.3, while [O III] exposes a quasar-driven outflow with v≈6050 km s−1 and an ionized outflow rate ≈1650 M⊙ yr−1. The cube maps a “train-wreck” triple merger: an older, massive NE companion (M⋆≈3.6×10^11 M⊙, age≈65 Myr) linked to the host by a gas bridge, plus a very young SE companion (age≈6.7 Myr, M⋆≈1.9×10^10 M⊙) with ongoing star formation. These results argue for merger-triggered early SMBH growth; a likely foreground z=1.135 galaxy may modestly lens the quasar (1<μ<2; <0.75 mag).

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Inspect the white-light and quasar-subtracted [O III] maps to see the four labeled regions, the gas bridge between the host and NE companion, and how the IFU [O III] morphology aligns with the HST F125W contours—key for confirming active interaction geometry.
Figure 2: Use the full 0.82–5.2 μm spectrum to verify line identifications across rest-UV/optical, the Fe II pseudo-continuum zones, and continuum level used for luminosities feeding the mass and Eddington-ratio estimates.
Figure 3: Examine the QubeSpec fits around Hβ–[O III] and Hα–[N II] to read off BLR FWHM for the virial MBH and the [O III] outflow wing parameters (velocity and flux), noting the stated aperture corrections applied to Hα and Hβ.
Figure 4: Compare the MBH and Lbol/LEdd posteriors across multiple single-epoch calibrations (G05, V06, DB20/24, C23) to gauge systematic spread and the adopted combined estimate for this source.

High-velocity outflows in [OIII] emitters at z=2.5-9 from JWST NIRSpec medium-resolution spectroscopy

Ryan A. Cooper, Karina I. Caputi, Edoardo Iani, Pierluigi Rinaldi, Guillaume Desprez, Rafael Navarro-Carrera

Theme match 4/5

Digest

From the full JADES NIRSpec R~1000 sample of 1087 [O III] 5007 emitters at z=2.5–9, the authors flag 40 galaxies with clear blue-side line broadening, of which 34 are robust ionized outflow candidates and 6 may reflect rotating clumps. The outflows occur mostly in star-forming systems (~65% starbursts) spanning log10(M*/Msun)=7.5–11, and include two type-2 AGN candidates plus one little red dot. They measure a median outflow velocity of 531(+146/−159) km/s and a global incidence of 3.4%, higher velocities and lower incidence than prior work, attributed to R1000 resolution and stricter selection. No v_out–M* or SFR correlations are found; v_out/v_esc has a median 0.77 (generally bound), while mass loading anti-correlates with M* up to ~10^10 Msun, exceeding unity in many M*<10^9 Msun galaxies.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 3: Inspect the [O III] 5007 profile for JADES-GN+189.11339-62.22768 to see the asymmetric blue wing and how adding a broad Gaussian component reduces residuals—key for understanding the outflow identification and typical broad-component widths/offsets.
Figure 4: Outflow velocity versus redshift with morphology-coded symbols; check where the two type-2 AGN candidates and the LRD fall relative to the star-forming sample and to literature points (Xu23, Ca24), and whether the highest velocities cluster at any z or morphology.
Figure 2: S/N distribution of all [O III] emitters versus the outflow subset; use this to gauge completeness and the effective S/N>5 threshold where blue-wing detections become reliable.
Figure 1: Comparison of [O III] fluxes (MSAEXP vs JADES catalog); verify flux calibration consistency that underpins line-profile fitting and derived outflow velocities/mass-loading estimates.

Week 9, 2025

Tentative detection of neutral gas in a Little Red Dot at $z=4.46$

Digest

Key figures to inspect

Tags

JWST's PEARLS: A z=6 quasar in a train-wreck galaxy merger system

Digest

Key figures to inspect

Tags

High-velocity outflows in [OIII] emitters at z=2.5-9 from JWST NIRSpec medium-resolution spectroscopy

Digest

Key figures to inspect

Tags