S. Tacchella

JADES: Dynamical Measurements of Dark Matter Halo Masses at $z \approx 7$ Using Galaxy Pairs

We present dynamical measurements of dark matter halo masses at $z\approx7$ using galaxy pairs. Galaxy pairs in the early Universe are usually in their first infall, before substantial orbital evolution or phase mixing. Their relative velocities closely trace the halo mass, especially when the pair separation is near t...

A Steep-extinction Quasi-stellar Object at z = 4.6: JWST Evidence for Abundant Small Dust Grains

The rapid accumulation of massive dust reservoirs in the early Universe remains a major challenge in astrophysics. While core-collapse supernovae can inject large dust grains (a ≳ 0.1 μm) on short timescales, explaining the total dust budgets in the early Universe likely requires efficient grain growth in the interstel...

Mergers lighting the early Universe: modest star-formation enhancement without evidence for AGN or Lyα triggering

Galaxy mergers and interactions are often invoked to explain enhanced star formation, black hole growth, and mass build-up of galaxies at later cosmic times, but their effect is poorly understood at high redshift (z > 2). We use JADES data to analyse a mass-complete sample of 1968 galaxies at z = 3 − 9 with log(M⋆/M⊙...

Source--Line Associations in JWST/NIRSpec Dense-Shutter Spectroscopy

We demonstrate the feasibility of source--line association in JWST/NIRSpec dense-shutter spectroscopy, with $\sim$2000 sources observed simultaneously per pointing regardless of spectral overlap. While JWST wide-field slitless spectroscopy (WFSS) can disentangle overlapping spectra using two grisms with perpendicular d...

JADES data release 4 – Paper I . Sample selection, observing strategy and redshifts of the complete spectroscopic sample

Spatially Resolved Active Galactic Nucleus Ionization and Star Formation at Cosmic Noon with JWST/JEMS

At cosmic noon (z ≈ 2–3), both star formation and active galactic nucleus (AGN) activity peaked, each playing a significant role in ionizing interstellar gas on galaxy-wide scales. The spatial distribution of this ionized gas provides a direct probe of how AGN and stellar ionization influence the gaseous reservoirs of...

JADES: The Star Formation and Dust Reddening Properties of Galaxies at 3 < z < 7

We present the star formation and dust content properties for a sample of 646 galaxies at redshifts 3 < z < 7 as part of the JADES survey. Our analysis is based on measurements of the Hα/Hβ Balmer decrement using medium resolution (R ∼ 1000) spectroscopic observations with the JWST/NIRSpec microshutter assembly. Stella...

CERIDWEN: Fast and Flexible GPU-Accelerated Stellar Population Inference

JWST has increased both the number of high-redshift galaxies with high-quality spectral energy distributions (SEDs) and their information content. In parallel, wide-area surveys from Euclid, Rubin's LSST, and Roman will increase galaxy samples by orders of magnitude. Analysing these datasets requires stellar-population...

PhotoIFU: NIRCam as a Photometric Integral Field Unit for Mapping Feedback in Galaxies

We present PhotoIFU, a workflow that uses deep multi-band imaging as a low-resolution photometric integral field unit. Applied to PSF-matched JWST/NIRCam imaging, PhotoIFU treats each spatial pixel as a coarse SED element and fits the pixel SEDs with Prospector to map resolved stellar-population and ISM-related propert...