A first look at the SMACS0723 JWST ERO: spectroscopic redshifts, stellar masses, and star-formation histories
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A first look at the SMACS0723 JWST ERO : spectroscopic redshifts, stellar masses, and star-formation histories. / Carnall, A. C.; Begley, R.; McLeod, D. J.; Hamadouche, M. L.; Donnan, C. T.; McLure, R. J.; Dunlop, J. S.; Milvang-Jensen, B.; Bondestam, C. L.; Cullen, F.; Jewell, S. M.; Pollock, C. L.
In: Monthly Notices of the Royal Astronomical Society, Vol. 518, No. 1, 01.01.2023, p. L45-L50.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - A first look at the SMACS0723 JWST ERO
T2 - spectroscopic redshifts, stellar masses, and star-formation histories
AU - Carnall, A. C.
AU - Begley, R.
AU - McLeod, D. J.
AU - Hamadouche, M. L.
AU - Donnan, C. T.
AU - McLure, R. J.
AU - Dunlop, J. S.
AU - Milvang-Jensen, B.
AU - Bondestam, C. L.
AU - Cullen, F.
AU - Jewell, S. M.
AU - Pollock, C. L.
PY - 2023/1/1
Y1 - 2023/1/1
N2 - We present a first-look analysis of the JWST ERO data in the SMACS J0723.3-7327 cluster field. We begin by reporting 10 new spectroscopic redshifts from lambda(obs) = 1.8-5.2 mu m NIRSpec medium-resolution (R = lambda/Delta lambda = 1000) data. These are determined via multiple high-SNR emission line detections with five objects at 1 < z < 3 displaying multiple rest-frame near-infrared Hydrogen Paschen lines, and five objects at 5 < z < 9 displaying rest-frame optical Oxygen and Hydrogen Balmer lines. For the five higher-redshift galaxies we extract fluxes in six NIRCam bands spanning lambda(obs) = 0.8-5 mu m and perform spectral energy distribution fitting in combination with existing HST photometry. The 7 < z < 9 objects exhibit a U-shaped pattern across the F277W, F356 W, and F444 W bands, indicating a Balmer break seen in emission (Balmer jump) and high-equivalent-width [O III] emission. This indicates an extremely young stellar population with the bulk of the current mass having formed within the past 10 Myr. We report robust stellar masses and mean stellar ages from our spectral fitting with the four z > 6 galaxies exhibiting low-stellar masses from log (10) (M-*/M-circle dot) = 7.1-8.2, and correspondingly young mean stellar ages of only a few Myr. This work highlights the critical importance of combining large upcoming NIRCam surveys with NIRSpec follow-up to measure the spectroscopic redshifts necessary to robustly constrain physical parameters.
AB - We present a first-look analysis of the JWST ERO data in the SMACS J0723.3-7327 cluster field. We begin by reporting 10 new spectroscopic redshifts from lambda(obs) = 1.8-5.2 mu m NIRSpec medium-resolution (R = lambda/Delta lambda = 1000) data. These are determined via multiple high-SNR emission line detections with five objects at 1 < z < 3 displaying multiple rest-frame near-infrared Hydrogen Paschen lines, and five objects at 5 < z < 9 displaying rest-frame optical Oxygen and Hydrogen Balmer lines. For the five higher-redshift galaxies we extract fluxes in six NIRCam bands spanning lambda(obs) = 0.8-5 mu m and perform spectral energy distribution fitting in combination with existing HST photometry. The 7 < z < 9 objects exhibit a U-shaped pattern across the F277W, F356 W, and F444 W bands, indicating a Balmer break seen in emission (Balmer jump) and high-equivalent-width [O III] emission. This indicates an extremely young stellar population with the bulk of the current mass having formed within the past 10 Myr. We report robust stellar masses and mean stellar ages from our spectral fitting with the four z > 6 galaxies exhibiting low-stellar masses from log (10) (M-*/M-circle dot) = 7.1-8.2, and correspondingly young mean stellar ages of only a few Myr. This work highlights the critical importance of combining large upcoming NIRCam surveys with NIRSpec follow-up to measure the spectroscopic redshifts necessary to robustly constrain physical parameters.
KW - Galaxies: distances and redshifts
KW - Galaxies: high-redshift
KW - Galaxies: star formation
KW - ULTRA-DEEP FIELD
KW - LUMINOSITY FUNCTION
KW - FORMATION RATES
KW - GALAXY
KW - RESOLUTION
KW - IMAGES
KW - POPULATION
KW - RELEASE
U2 - 10.1093/mnrasl/slac136
DO - 10.1093/mnrasl/slac136
M3 - Journal article
VL - 518
SP - L45-L50
JO - Royal Astronomical Society. Monthly Notices
JF - Royal Astronomical Society. Monthly Notices
SN - 0035-8711
IS - 1
ER -
ID: 338299583