J/ApJ/908/154 Complete sp. for the lensed galaxy SDSS J1723+3411 (Rigby+, 2021)
A comparison of rest-frame ultraviolet and optical emission-line diagnostics in
the lensed galaxy SDSS J1723+3411 at redshift z=1.3293.
Rigby J.R., Florian M., Acharyya A., Bayliss M., Gladders M.D., Sharon K.,
Brammer G., Momcheva I., LaMassa S., Bian F., Dahle H., Johnson T.,
Kewley L., Murray K., Whitaker K., Wuyts E.
<Astrophys. J., 908, 154 (2021)>
=2021ApJ...908..154R 2021ApJ...908..154R
ADC_Keywords: Galaxies; Spectra, optical; Ultraviolet; Spectra, infrared;
Gravitational lensing
Keywords: Gravitational lensing ; Galaxy evolution ; Atomic spectroscopy ;
Spectroscopy ; Emission line galaxies ; Starburst galaxies ;
Interstellar medium
Abstract:
For the extremely bright lensed galaxy SDSSJ1723+3411 at z=1.3293, we
analyze spatially integrated MMT, Keck, and Hubble Space Telescope
spectra that fully cover the rest-frame wavelength range of
1400-7200Å. We also analyze near-IR spectra from Gemini that cover
Hα for a portion of the lensed arc. We report fluxes for
42 detected emission lines, and upper limits for an additional 22.
This galaxy has extreme emission-line ratios and high equivalent
widths that are characteristic of extreme emission-line galaxies. We
compute strong emission-line diagnostics from both the rest-frame
optical and rest-frame ultraviolet (UV), to constrain physical
conditions and test the spectral diagnostics themselves. We tightly
determine the nebular physical conditions using the most reliable
diagnostics, and then compare to results from other diagnostics. We
find disappointing performance from the UV-only diagnostics: they
either are unable to measure the metallicity or dramatically
underestimate it; they overestimate the pressure; and the UV
diagnostic of ionization parameter has a strong metallicity dependence
in this regime. Based on these results, we suggest that upcoming James
Webb Space Telescope (JWST) spectroscopic surveys of galaxies in the
reionization epoch should invest the additional integration time to
capture the optical [OII] and [OIII] emission lines, and not rely
solely on the rest-frame UV emission lines. We make available the
spectra; they represent one of the highest-quality emission-line
spectral atlases of star-forming galaxies available beyond the local
universe, and will aid the planning of observations with JWST.
Description:
In this paper, for the bright gravitationally lensed giant arc
SDSS_J1723+3411 at z=1.3293 (Figure 1), we analyze spectra from
instruments on four telescopes: the Blue Channel spectrograph on the
MMT, the Echellette Spectrograph and Imager (ESI) on the Keck II
telescope, the WFC3-IR G102 and G141 grisms onboard the Hubble Space
Telescope (HST), and the Gemini Near-Infrared Spectrograph (GNIRS) on
the Gemini North telescope. All but the Gemini/GNIRS spectra are
spatially integrated over the giant arc; the Gemini/GNIRS spectrum
covers a small portion of the arc. See Figure 2.
We obtained imaging of SDSSJ1723+3411 with the UVIS and IR channels of
the WFC3 instrument onboard HST through guest observer program #13003
(PI Gladders). The filters used were F390W, F775W, F1110W, and F160W,
at depths of 2368s, 2380s, 1112s, and 1112s respectively.
Additional WFC3-IR imagery was also obtained in the F105W and F140W
filters through guest observer program #14230 (PI Rigby).
We obtained spectra of SDSSJ1723+3411 with the WFC3 instrument onboard
HST, using the IR channel and the G102 and G141 grisms, in guest
observer program #14230 (PI Rigby). Eight orbits of grism spectroscopy
were obtained on UT dates 2016-Jan-18, 2016-Jan-19, 2016-Jul-11, and
2016-Jul-14. The total integration times were 2.76hr in each of the
G102 and G141 grisms. See Section 2.3.2.
We observed SDSSJ1723+3411 with the Blue Channel spectrograph on the
6.5m MMT Observatory telescope on UT 2014 May 5 beginning at 09:20 UT.
Observing time was granted through the Harvard-Smithsonian Center
for Astrophysics. Science exposures of 2400s and 1200s were taken at
central wavelengths of 4005Å and 4205Å, respectively.
See Section 2.3.3.
We obtained spectra of SDSSJ1723+3411 using the Echellette
Spectrograph and Imager (ESI) on the Keck II telescope. Observations
were made on UT 2016 August 27 and UT 2016 August 28; observing time
was granted through Australian National University. The echellette
mode and the 1" slit were used for all observations, which provides a
spectral resolution of R∼4000. See Section 2.3.4.
We obtained spectra of SDSSJ1723+3411 with the GNIRS on the Gemini
North telescope as part of program GN-2016B-FT-11 (PI Rigby).
Observations were obtained on UT 2016 September 7, using the short
camera, cross-dispersing prism ("SXD" mode), the 03 slit, and the
111lines/mm grating with the central wavelength set to 1.529um. This
setup should provide a spectral resolution of R=5900. The spectra
covered observed wavelengths of 1.46-1.60um, which correspond to
rest-frame wavelengths of 0.627-0.687um. The effective integration
time was 2970s. See Section 2.3.5.
All spectra were corrected for foreground reddening from the Milky Way
galaxy, using the value of E(B-V)=0.03415 measured by
Green+ (2015ApJ...810...25G 2015ApJ...810...25G). All spectra have had the barycentric
correction applied, and all wavelengths are listed in vacuum. Rest
wavelengths are from NIST.
We use a solar oxygen abundance of 12+log(O/H)=8.72
(Asplund+ 2009ARA&A..47..481A 2009ARA&A..47..481A).
Objects:
-------------------------------------------------------------------------
RA (ICRS) DE Designation(s)
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17 23 36.49 +34 11 55.8 SGAS 1723 = [SAB2013] SDSS J1723+3411 source
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
fig7keck.dat 90 8065 *Keck/ESI spectrum of SGAS 1723
fig7mmt.dat 90 2982 *MMT Blue Channel spectrum of SGAS J1723
fig7g102.dat 102 196 *HST/WFC-3 G102 grism spectrum of S1723, from
both roll angles
fig7g141.dat 102 163 *HST/WFC-3 G141 grism spectrum of S1723, from
both roll angles
fig7comp.dat 90 7425 *Composite convenience spectrum
for SDSS J1723+3411 (comprised of portions of
the MMT, ESI, and WFC3 spectra)
fig8.dat 65 359 Combined high-resolution GNIRS spectra for S1723
--------------------------------------------------------------------------------
Note on fig7*.dat: Milky Way reddening has been corrected.
The composite convenience spectrum ignores spectral overlap, picks one
spectrum for each wavelength, as follows:
MMT Blue Channel 3200--4750Å; Keck ESI 4750--8500Å;
HST/WFC-IR G102 grism 8500--11000Å; HST/WFC-IR G141 grism 11000--16250Å
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See also:
J/A+A/448/955 : Abundances of emission galaxies in SDSS-DR3 (Izotov+, 2006)
J/ApJ/795/165 : Line ratios in z∼2-3 galaxies KBSS-MOSFIRE (Steidel+, 2014)
J/ApJ/814/L6 : CIII emission in near & far star-forming galax (Rigby+, 2015)
J/ApJ/822/42 : z∼3.3 star-forming galaxies NIR spectra (Onodera+, 2016)
J/ApJ/817/118 : SFR-M* relation from ZFOURGE (Tomczak+, 2016)
J/AJ/155/104 : MEGaSaURA. I. The sample and the spectra (Rigby+, 2018)
J/A+A/641/A118 : Mean rest-UV spectra of Lya emitters at z>3 (Feltre+, 2020)
J/ApJS/247/12 : Strong lens models for 37 clusters from SGAS (Sharon+, 2020)
Byte-by-byte Description of file: fig7[kmc]*.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 F19.13 0.1nm lambda [3000.8/16233] Wavelength (vacuum)
in Angstroms
21- 43 E23.18 cW/m2/nm Flux ?=0 Flux (f-lambda) in erg/s/cm2/Å (1)
45- 66 E22.17 cW/m2/nm e_Flux ?=0 Flux uncertainty
68- 90 E23.18 cW/m2/nm CFlux ? Flux continuum fit (not for composite
spectrum)
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Note (1): Scaled Keck/ESI flux so that sum of [OII] 3727+3729 fluxes matches
flux of those lines in HST/WFC-IR G102. Factor was 0.5727
Scaled MMT flux so that sum of CIII in MMT matches sum of those lines
in ESI, after ESI scaled to HST/WFC-IR G102. Factor was 1.3382.
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Byte-by-byte Description of file: fig7g*.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.1 0.1nm lambda [7475/17613] Wavelength (vacuum)
in Angstroms
9- 31 E23.18 cW/m2/nm Flux ?=0 Flux (f-lambda) in erg/s/cm2/Å
33- 54 E22.17 cW/m2/nm e_Flux ?=0 Flux uncertainty
56- 78 E23.18 cW/m2/nm CFlux Flux continuum fit
80-102 E23.18 cW/m2/nm Flux-c Flux minus continuum fit
-------------------------------------------------------------------------------
Byte-by-byte Description of file: fig8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 F18.12 0.1nm lambda [15000.85/15499.83] Wavelength (vacuum)
barycentric-corrected in Angstroms
20- 42 E23.18 cW/m2/nm Flux [-4.1e-17/4.9e-16] Flux (f-lambda)
in erg/s/cm2/Å (1)
44- 65 E22.17 cW/m2/nm e_Flux [3.9e-18/1.1e-16] Flux uncertainty
--------------------------------------------------------------------------------
Note (1): Scaled GNIRS spectrum to match Halpha flux in WFC-IR G141, by factor
5.184170877838979e-18.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 23-Feb-2024