J/AJ/169/207 Green Chile Cat: Extended nebulae SDSS photometry (Dijeau+, 2025)
The Green Chile Project. I. A new catalog of low-redshift extended emission-line
nebulae.
Dijeau A.F., Prescott M.K.M., Sanderson K.N.
<Astron. J., 169, 207 (2025)>
=2025AJ....169..207D 2025AJ....169..207D
ADC_Keywords: Active gal. nuclei; Galaxies, photometry; Optical
Keywords: Active galactic nuclei ; Active galaxies ; Emission line galaxies ;
Extragalactic astronomy ; Galaxy evolution
Abstract:
Extended emission-line nebulae (EELN) around galaxies allow us to
study their host galaxies and their surrounding environments. EELN can
provide insights into the physical properties of the extended gas and,
when powered by active galactic nuclei (AGN), they can constrain the
ionization history of the central engine as well. Of interest is a
sample of low-redshift EELN powered by AGN at z∼0.3 that were
discovered in the Sloan Digital Sky Survey (SDSS) through color
selection. Colloquially called "Green Beans," due to strong, spatially
extended [OIII]λ5007 emission dominating the r-band flux,
they have been shown to be low-redshift counterparts to
higher-redshift Lyα nebulae. However, only 17 Green Bean EELN
are known to exist at z∼0.3, and the original color selection was
subsequently found to be biased in terms of host galaxy properties. In
order to mitigate these biases and expand the known sample, we have
developed a new, physically motivated selection approach, based on
simulated EELN at z∼0.3, with well-defined physical properties
([OIII]λ5007 rest-frame equivalent width and continuum
spectral slope). With this improved selection approach, we have
generated a new sample of 165 EELN candidates: the "Green Chile"
catalog. Of the 13 candidates with existing SDSS/Baryon Oscillation
Spectroscopic Survey spectra, we confirm that five are EELN with
[OIII]λ5007 equivalent widths >200Å and emission-line
ratios indicative of AGN powering.
Description:
In this paper, we develop physically motivated criteria to search for
an unbiased sample of AGN-powered extended emission-line nebulae
(EELN) at z∼0.3. We apply the new selection to SDSS photometry,
remove artifacts by crossmatching with DESI Legacy Imaging Survey (LS)
data, and generate a new "Green Chile" (GC) catalog of candidate
EELN.
We applied our new, physically motivated selection criteria to the
photometric catalog of SDSS DR16 (V/154). The selection criteria were
applied to the SDSS model magnitudes in the g (482nm), r (624.7nm),
and i (763.5nm) bands. To select for extended emission, as done
previously, we required that the r-band Petrosian radii of selected
objects be greater than 2". Also, following previous work, we required
the point-spread-function magnitude errors in the g, r, and i bands to
be <0.04.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 57 165 Clean Green Chile Catalog
table6.dat 57 78 Additional objects from the "Raw" Green Chile
Catalog
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See also:
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
V/161 : DESI DR1 redshift catalog (DESI Col.+ 2025)
VII/292 : DESI Legacy Imaging Surveys DR8 photometric redshifts (Duncan, 2022)
J/MNRAS/421/1043 : Emission-line galaxies from SDSS DR7 (Shirazi+, 2012)
J/MNRAS/436/718 : Extremely faint planetary nebulae in SDSS (Yuan+, 2013)
J/MNRAS/465/1831 : SDSS-IV eBOSS ELG UgrizW photometry (Delubac+, 2017)
J/ApJ/854/29 : High-EW [OIII] and Hα emitters from 3D-HST (Maseda+, 2018)
J/MNRAS/485/1085 : Classification of emission-line galaxies (Stampoulis+, 2019)
J/MNRAS/507/4646 : SDSS DR16 white dwarf and subdwarf stars (Kepler+, 2021)
J/MNRAS/526/4768 : Galaxy Zoo DESI (Walmsley+, 2023)
J/ApJS/266/34 : Planetary nebulae with GALEX, SDSS, PS1 (Gomez-Munoz+, 2023)
J/ApJS/267/16 : Strong [OIII]5007 emission-line compact galaxies (Liu+, 2023)
J/ApJS/273/19 : Elemental abundances from DESI EDR spectra (Zhang+, 2024)
J/ApJS/272/39 : Galaxy clusters from DESI Legacy Surveys & WISE (Wen+, 2024)
J/MNRAS/542/3315 : Infrared and optical emission-line diagnostics (Durre, 2025)
http://www.sdss.org/dr16/ : SDSS DR16 home page
http://skyserver.sdss.org/dr16/en/home.aspx : SDSS DR16 data access
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- objID SDSS DR16 (V/154) object identifier
21- 29 F9.5 deg RAdeg Right Ascension (J2000)
31- 39 F9.5 deg DEdeg Declination (J2000)
41- 45 F5.2 mag gmag [17.89/20.97] SDSS DR16 AB g-band model magnitude
47- 51 F5.2 mag rmag [17.01/19.91] SDSS DR16 AB r-band model magnitude
53- 57 F5.2 mag imag [17.35/21.09] SDSS DR16 AB i-band model magnitude
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- objID SDSS DR16 (V/154) object identifier
21- 29 F9.5 deg RAdeg Right Ascension (J2000)
31- 39 F9.5 deg DEdeg Declination (J2000)
41- 45 F5.2 mag gmag [18.11/21.34] SDSS DR16 AB g-band model magnitude
47- 51 F5.2 mag rmag [17.07/19.93] SDSS DR16 AB r-band model magnitude
53- 57 F5.2 mag imag [17.4/20.61] SDSS DR16 AB i-band model magnitude
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History:
From electronic version of the journal
References:
Dijeau et al. Pap I This catalog
(End) Prepared by [AAS], Robin Leichtnam [CDS] 12-Jan-2026