Kavli Affiliate: Anna Frebel
| First 5 Authors: Rohan P. Naidu, Jorryt Matthee, Ivan Kramarenko, Andrea Weibel, Gabriel Brammer
| Summary:
Dwarf galaxies hold the key to crucial frontiers of astrophysics, however,
their faintness renders spectroscopy challenging. Here we present the JWST
Cycle 2 survey, All the Little Things (ALT, PID 3516), which is designed to
seek late-forming Pop III stars and the drivers of reionization at $zsim6-7$.
ALT has acquired the deepest NIRCam grism spectroscopy yet (7-27 hr), at JWST’s
most sensitive wavelengths (3-4 $mu$m), covering the powerful lensing cluster
Abell 2744. Over the same 30 arcmin$^2$, ALT’s ultra-deep F070W+F090W imaging
($sim$30 mag) enables selection of very faint sources at $z>6$. We demonstrate
the success of ALT’s novel “butterfly" mosaic to solve spectral confusion and
contamination, and introduce the “Allegro" method for emission line
identification. By collecting spectra for every source in the field of view,
ALT has measured precise ($Rsim1600$) redshifts for 1630 sources at
$z=0.2-8.5$. This includes one of the largest samples of distant dwarf
galaxies: [1015, 475, 50] sources less massive than the SMC, Fornax, and
Sculptor with $log(M_{*}/M_{odot})<$[8.5, 7.5, 6.5]. We showcase ALT’s
discovery space with: (i) spatially resolved spectra of lensed clumps in
galaxies as faint as $M_{rm{UV}}sim-15$; (ii) large-scale clustering —
overdensities at $z$=[2.50, 2.58, 3.97, 4.30, 5.66, 5.77, 6.33] hosting massive
galaxies with striking Balmer breaks; (iii) small-scale clustering — a system
of satellites around a Milky Way analog at $zsim6$; (iv) spectroscopically
confirmed multiple images that help constrain the lensing model underlying all
science in this legacy field; (v) sensitive star-formation maps based on
dust-insensitive tracers such as Pa$alpha$; (vi) direct spectroscopic
discovery of rare sources such as AGN with ionized outflows. These results
provide a powerful proof of concept for how grism surveys maximize the
potential of strong lensing fields.
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