Broad Emission Lines in Optical Spectra of Hot, Dust-obscured Galaxies Can Contribute Significantly to JWST/NIRCam Photometry
Publikation: Bidrag til tidsskrift › Letter › Forskning › fagfællebedømt
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Broad Emission Lines in Optical Spectra of Hot, Dust-obscured Galaxies Can Contribute Significantly to JWST/NIRCam Photometry. / McKinney, Jed; Finnerty, Luke; Casey, Caitlin M.; Franco, Maximilien; Long, Arianna S.; Fujimoto, Seiji; Zavala, Jorge A.; Cooper, Olivia; Akins, Hollis; Pope, Alexandra; Armus, Lee; Soifer, B. T.; Larson, Kirsten; Matthews, Keith; Melbourne, Jason; Cushing, Michael.
I: Astrophysical Journal Letters, Bind 946, Nr. 2, 39, 01.04.2023.Publikation: Bidrag til tidsskrift › Letter › Forskning › fagfællebedømt
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T1 - Broad Emission Lines in Optical Spectra of Hot, Dust-obscured Galaxies Can Contribute Significantly to JWST/NIRCam Photometry
AU - McKinney, Jed
AU - Finnerty, Luke
AU - Casey, Caitlin M.
AU - Franco, Maximilien
AU - Long, Arianna S.
AU - Fujimoto, Seiji
AU - Zavala, Jorge A.
AU - Cooper, Olivia
AU - Akins, Hollis
AU - Pope, Alexandra
AU - Armus, Lee
AU - Soifer, B. T.
AU - Larson, Kirsten
AU - Matthews, Keith
AU - Melbourne, Jason
AU - Cushing, Michael
PY - 2023/4/1
Y1 - 2023/4/1
N2 - Selecting the first galaxies at z > 7 - 10 from JWST surveys is complicated by z < 6 contaminants with degenerate photometry. For example, strong optical nebular emission lines at z < 6 may mimic JWST/NIRCam photometry of z > 7-10 Lyman-break galaxies (LBGs). Dust-obscured 3 < z < 6 galaxies in particular are potentially important contaminants, and their faint rest-optical spectra have been historically difficult to observe. A lack of optical emission line and continuum measures for 3 < z < 6 dusty galaxies now makes it difficult to test their expected JWST/NIRCam photometry for degenerate solutions with NIRCam dropouts. Toward this end, we quantify the contribution by strong emission lines to NIRCam photometry in a physically motivated manner by stacking 21 Keck II/NIRES spectra of hot, dust-obscured, massive (logM(*)/M-circle dot.greater than or similar to 10-11) and infrared (IR) luminous galaxies at z similar to 1-4. We derive an average spectrum and measure strong narrow (broad) [O III](5007) and H alpha features with equivalent widths of 130 +/- 20 angstrom (150 +/- 50 angstrom) and 220 +/- 30 angstrom (540 +/- 80 angstrom), respectively. These features can increase broadband NIRCam fluxes by factors of 1.2 - 1.7 (0.2-0.6 mag). Due to significant dust attenuation (A(V) similar to 6), we find H alpha+[N II] to be significantly brighter than [O III]+H beta and therefore find that emission-line dominated contaminants of high -z galaxy searches can only reproduce moderately blue perceived UV continua of S-lambda alpha lambda(beta) with beta > - 1.5 and z > 4. While there are some redshifts (z similar to 3.75) where our stack is more degenerate with the photometry of z > 10 LBGs at lambda(rest) similar to 0.3-0.8 mu m, redder filter coverage beyond lambda(obs) > 3.5 mu m and farIR/submillimeter follow-up may be useful for breaking the degeneracy and making a crucial separation between two fairly unconstrained populations, dust-obscured galaxies at z similar to 3-6 and LBGs at z > 10.
AB - Selecting the first galaxies at z > 7 - 10 from JWST surveys is complicated by z < 6 contaminants with degenerate photometry. For example, strong optical nebular emission lines at z < 6 may mimic JWST/NIRCam photometry of z > 7-10 Lyman-break galaxies (LBGs). Dust-obscured 3 < z < 6 galaxies in particular are potentially important contaminants, and their faint rest-optical spectra have been historically difficult to observe. A lack of optical emission line and continuum measures for 3 < z < 6 dusty galaxies now makes it difficult to test their expected JWST/NIRCam photometry for degenerate solutions with NIRCam dropouts. Toward this end, we quantify the contribution by strong emission lines to NIRCam photometry in a physically motivated manner by stacking 21 Keck II/NIRES spectra of hot, dust-obscured, massive (logM(*)/M-circle dot.greater than or similar to 10-11) and infrared (IR) luminous galaxies at z similar to 1-4. We derive an average spectrum and measure strong narrow (broad) [O III](5007) and H alpha features with equivalent widths of 130 +/- 20 angstrom (150 +/- 50 angstrom) and 220 +/- 30 angstrom (540 +/- 80 angstrom), respectively. These features can increase broadband NIRCam fluxes by factors of 1.2 - 1.7 (0.2-0.6 mag). Due to significant dust attenuation (A(V) similar to 6), we find H alpha+[N II] to be significantly brighter than [O III]+H beta and therefore find that emission-line dominated contaminants of high -z galaxy searches can only reproduce moderately blue perceived UV continua of S-lambda alpha lambda(beta) with beta > - 1.5 and z > 4. While there are some redshifts (z similar to 3.75) where our stack is more degenerate with the photometry of z > 10 LBGs at lambda(rest) similar to 0.3-0.8 mu m, redder filter coverage beyond lambda(obs) > 3.5 mu m and farIR/submillimeter follow-up may be useful for breaking the degeneracy and making a crucial separation between two fairly unconstrained populations, dust-obscured galaxies at z similar to 3-6 and LBGs at z > 10.
KW - WISE-SELECTED HOT
KW - STAR-FORMATION RATE
KW - NEBULAR EMISSION
KW - LUMINOSITY FUNCTION
KW - CONTINUUM SLOPES
KW - MASSIVE GALAXIES
KW - ALMA SURVEY
KW - REDSHIFT
KW - JWST
KW - EVOLUTION
U2 - 10.3847/2041-8213/acc322
DO - 10.3847/2041-8213/acc322
M3 - Letter
VL - 946
JO - The Astrophysical Journal Letters
JF - The Astrophysical Journal Letters
SN - 2041-8205
IS - 2
M1 - 39
ER -
ID: 345368734