4 research outputs found
JWST's PEARLS: dust attenuation and gravitational lensing in the backlit-galaxy system VV 191
We derive the spatial and wavelength behavior of dust attenuation in the
multiple-armed spiral galaxy VV191b using backlighting by the superimposed
elliptical system VV191a in a pair with an exceptionally favorable geometry for
this measurement. Imaging using JWST and HST spans the wavelength range 0.3-4.5
microns with high angular resolution, tracing the dust in detail from 0.6 to
1.5 microns. Distinct dust lanes continue well beyond the bright spiral arms,
and trace a complex web, with a very sharp radial cutoff near 1.7 Petrosian
radii. We present attenuation profiles and coverage statistics in each band at
radii 14-21 kpc. We derive the attenuation law with wavelength; the data both
within and between the dust lanes clearly favor a stronger reddening behavior
(R ~ 2.0 between 0.6 and 0.9 microns, approaching unity by 1.5 microns) than
found for starbursts and star-forming regions of galaxies. Power-law extinction
behavior lambda^(-beta) gives beta=2.1 from 0.6-0.9 microns. R decreases at
increasing wavelengths (R~1.1 between 0.9 and 1.5 microns), while beta steepens
to 2.5. Mixing regions of different column density flattens the wavelength
behavior, so these results suggest a different grain population than in our
vicinity. The NIRCam images reveal a lens arc and counterimage from a
background galaxy at z~1, spanning 90 degrees azimuthally at 2.8" from the
foreground elliptical galaxy nucleus, and an additional weakly-lensed galaxy.
The lens model and imaging data give a mass/light ratio 7.6 in solar units
within the Einstein radius 2.0 kpc.Comment: Accepted by Astron. J. Analysis redone since submission, using
updated JWST calibrations. Dust reddening behavior is steeper with wavelength
and lensed galaxy redshift lower than we first derive
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JWST PEARLS. Prime Extragalactic Areas for Reionization and Lensing Science: Project Overview and First Results
We give an overview and describe the rationale, methods, and first results from NIRCam images of the JWST “Prime Extragalactic Areas for Reionization and Lensing Science” (PEARLS) project. PEARLS uses up to eight NIRCam filters to survey several prime extragalactic survey areas: two fields at the North Ecliptic Pole (NEP); seven gravitationally lensing clusters; two high redshift protoclusters; and the iconic backlit VV 191 galaxy system to map its dust attenuation. PEARLS also includes NIRISS spectra for one of the NEP fields and NIRSpec spectra of two high-redshift quasars. The main goal of PEARLS is to study the epoch of galaxy assembly, active galactic nucleus (AGN) growth, and First Light. Five fields—the JWST NEP Time-Domain Field (TDF), IRAC Dark Field, and three lensing clusters—will be observed in up to four epochs over a year. The cadence and sensitivity of the imaging data are ideally suited to find faint variable objects such as weak AGN, high-redshift supernovae, and cluster caustic transits. Both NEP fields have sightlines through our Galaxy, providing significant numbers of very faint brown dwarfs whose proper motions can be studied. Observations from the first spoke in the NEP TDF are public. This paper presents our first PEARLS observations, their NIRCam data reduction and analysis, our first object catalogs, the 0.9-4.5 μm galaxy counts and Integrated Galaxy Light. We assess the JWST sky brightness in 13 NIRCam filters, yielding our first constraints to diffuse light at 0.9-4.5 μm. PEARLS is designed to be of lasting benefit to the community
JWST PEARLS. Prime Extragalactic Areas for Reionization and Lensing Science: Project Overview and First Results
We give an overview and describe the rationale, methods, and first results from NIRCam images of the JWST “Prime Extragalactic Areas for Reionization and Lensing Science” (PEARLS) project. PEARLS uses up to eight NIRCam filters to survey several prime extragalactic survey areas: two fields at the North Ecliptic Pole (NEP); seven gravitationally lensing clusters; two high redshift protoclusters; and the iconic backlit VV 191 galaxy system to map its dust attenuation. PEARLS also includes NIRISS spectra for one of the NEP fields and NIRSpec spectra of two high-redshift quasars. The main goal of PEARLS is to study the epoch of galaxy assembly, active galactic nucleus (AGN) growth, and First Light. Five fields—the JWST NEP Time-Domain Field (TDF), IRAC Dark Field, and three lensing clusters—will be observed in up to four epochs over a year. The cadence and sensitivity of the imaging data are ideally suited to find faint variable objects such as weak AGN, high-redshift supernovae, and cluster caustic transits. Both NEP fields have sightlines through our Galaxy, providing significant numbers of very faint brown dwarfs whose proper motions can be studied. Observations from the first spoke in the NEP TDF are public. This paper presents our first PEARLS observations, their NIRCam data reduction and analysis, our first object catalogs, the 0.9-4.5 μm galaxy counts and Integrated Galaxy Light. We assess the JWST sky brightness in 13 NIRCam filters, yielding our first constraints to diffuse light at 0.9-4.5 μm. PEARLS is designed to be of lasting benefit to the community