J/ApJS/261/31 COS Legacy Archive Sp. Survey (CLASSY) treasury (Berg+, 2022)
The COS Legacy Archive Spectroscopy Survey (CLASSY) Treasury atlas.
Berg D.A., James B.L., King T., McDonald M., Chen Z., Chisholm J.,
Heckman T., Martin C.L., Stark D.P., Aloisi A., Amorin R.O.,
Arellano-Cordova K.Z., Bayliss M., Bordoloi R., Brinchmann J., Charlot S.,
Chevallard J., Clark I., Erb D.K., Feltre A., Gronke M., Hayes M., Henry A.,
Hernandez S., Jaskot A., Jones T., Kewley L.J., Kumari N., Leitherer C.,
Llerena M., Maseda M., Mingozzi M., Nanayakkara T., Ouchi M., Plat A.,
Pogge R.W., Ravindranath S., Rigby J.R., Sanders R., Scarlata C.,
Senchyna P., Skillman E.D., Steidel C.C., Strom A.L., Sugahara Y.,
Wilkins S.M., Wofford A., Xu X., The CLASSY Team
<Astrophys. J. Suppl. Ser., 261, 31 (2022)>
=2022ApJS..261...31B 2022ApJS..261...31B
ADC_Keywords: Spectra, ultraviolet; Spectra, optical; Galaxies, nearby;
Redshifts; Abundances; Reddening
Keywords: Galaxies ; Ultraviolet surveys ; Emission line galaxies ;
Interstellar line absorption ; Lyman-alpha galaxies ;
High-redshift galaxies
Abstract:
Far-ultraviolet (FUV; ∼1200-2000Å) spectra are fundamental to our
understanding of star-forming galaxies, providing a unique window on
massive stellar populations, chemical evolution, feedback processes,
and reionization. The launch of the James Webb Space Telescope will
soon usher in a new era, pushing the UV spectroscopic frontier to
higher redshifts than ever before; however, its success hinges on a
comprehensive understanding of the massive star populations and gas
conditions that power the observed UV spectral features. This requires
a level of detail that is only possible with a combination of ample
wavelength coverage, signal-to-noise, spectral-resolution, and sample
diversity that has not yet been achieved by any FUV spectral database.
We present the Cosmic Origins Spectrograph Legacy Spectroscopic Survey
(CLASSY) treasury and its first high-level science product, the CLASSY
atlas. CLASSY builds on the Hubble Space Telescope (HST) archive to
construct the first high-quality (S/N1500Å≳5/resel),
high-resolution (R∼15000) FUV spectral database of 45 nearby
(0.002<z<0.182) star-forming galaxies. The CLASSY atlas, available to
the public via the CLASSY website, is the result of optimally
extracting and coadding 170 archival+new spectra from 312 orbits of
HST observations. The CLASSY sample covers a broad range of properties
including stellar mass (6.2<logM*(M☉)<10.1), star formation
rate (-2.0<logSFR(M☉/yr)<+1.6), direct gas-phase metallicity
(7.0<12+log(O/H)<8.8), ionization (0.5<O32<38.0), reddening
(0.02<E(B-V)<0.67), and nebular density (10<ne(cm-3)<1120). CLASSY
is biased to UV-bright star-forming galaxies, resulting in a sample
that is consistent with the z∼0 mass-metallicity relationship, but is
offset to higher star formation rates by roughly 2dex, similar to z≳2
galaxies. This unique set of properties makes the CLASSY atlas the
benchmark training set for star-forming galaxies across cosmic time.
Description:
The COS Legacy Archive Spectroscopy Survey (CLASSY) combines
135 orbits of new HST data with 177 orbits of archival HST data, for a
total of 312 orbits, to complete the first atlas of high-quality
rest-FUV COS spectra of 45 local star-forming galaxies.
In order to complete the FUV spectral coverage of the CLASSY sample,
the archival observations were supplemented with 76 new HST/COS
spectroscopic data sets of 42 galaxies, compiled over 135 orbits in
Cycle 27 as part of PID 15840. These data consist of 27 G130M data
sets, 5 G160M data sets, 29 G185M data sets, and 8 G225M data sets.
Details of all individual data sets are provided in Table 2.
High-quality optical spectra have been compiled for the entire CLASSY
sample to ensure uniform determinations of galaxy properties.
Initially, much of the sample was selected from the SDSS, and so
archival SDSS spectra exist for 38 of the CLASSY galaxies. The
exceptions are J0036-3333, J0127-0619, J0144+0453, J0337-0502,
J0405-3648, J0934+5514, and J1444+4237. Instead, we use VLT/VIMOS
integral field unit (IFU) from James+ (2009MNRAS.398....2J 2009MNRAS.398....2J) for
J0127-0619, MMT Blue Channel Spectrograph spectra from
Senchyna+ (2019MNRAS.488.3492S 2019MNRAS.488.3492S) for J0144+0453 and J1444+4237,
Keck/KCWI IFU spectra from Rickards Vaught+ (2021ApJ...911L..17R 2021ApJ...911L..17R) for
J0337-0502, and VLT/MUSE IFU spectra for the remaining four galaxies.
To ensure robust direct Te measurements for J0808+3948, J0944+3442,
and J1545+0858, very high-S/N optical spectral were obtained using the
Multi-Object Double Spectrographs (MODS) on the Large Binocular
Telescope (LBT).
We gathered additional optical spectra from archival VLT/MUSE IFU
spectra and Keck/ESI spectra from R. L. Sanders et al. (2022, in
preparation), and spectra that were prioritized over the SDSS spectra
due to their superior S/N and spectral resolution.
The details of the ancillary optical spectra adopted for the CLASSY
sample are listed in Table 4.
The SDSS provides optical imaging in ugriz for 42 galaxies in the
CLASSY sample. For the other three, J0036-3333 and J0405-3648 have
grizY images from the DES (Abbott+ 2021, II/371), and J0337-0502 is
observed by the Pan-STARRS1 (Chambers+ 2016, II/349). For the UV, 43
galaxies (all but J0337-0502 and J1157+3220) have imaging in the NUV
and FUV available from GALEX (Martin+ 2005ApJ...619L...1M 2005ApJ...619L...1M ; see II/335).
Additionally, Wide-field Infrared Survey Explorer (WISE) W1 and W2
near-infrared (NIR) data are also available for the entire CLASSY
sample.
See Appendix C.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 107 217 CLASSY New+Archival HST/COS observations
table3.dat 43 45 Nominal and measured spectral resolution of
CLASSY coadded spectra
table4.dat 134 45 Ancillary optical spectra for the CLASSY
galaxy sample
table5.dat 120 45 CLASSY galaxy spectroscopy-derived properties
table6.dat 118 45 CLASSY galaxy photometry-derived properties
fits/* . 45 Individual CLASSY HLSP galaxy spectrum
in FITS format
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
II/349 : The Pan-STARRS release 1 (PS1) Survey - DR1 (Chambers+, 2016)
II/335 : Revised catalog of GALEX UV sources (GUVcat_AIS GR6+7) (Bianchi+ 2017)
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
II/371 : The Dark Energy Survey (DES): Data Release 2 (Abott+, 2021)
J/ApJS/178/247 : Hα and [NII] survey in local 11 Mpc (Kennicutt+, 2008)
J/ApJ/706/599 : Hα and UV SFR in the local volume (Lee+, 2009)
J/ApJS/190/233 : Spectroscopy & abundances of SINGS galaxies (Moustakas+, 2010)
J/A+A/561/A64 : Mrk 996 optical spectroscopy (Telles+, 2014)
J/ApJ/806/16 : CHemical Abundances of Spirals. I. NGC628 (Berg+, 2015)
J/ApJS/219/8 : SFR for WISE + SDSS spectroscopic galaxies (Chang+, 2015)
J/ApJ/814/L6 : CIII] emission in near & far star-forming gal. (Rigby+, 2015)
J/A+A/608/A139 : 237 Lyman-alpha spectra of MUSE-Wide survey (Gronke, 2017)
J/A+A/615/A78 : Spectral models for binary products (Goetberg+, 2018)
J/AJ/155/104 : MEGaSaURA. I. The sample and the spectra (Rigby+, 2018)
J/ApJ/869/123 : Keck Lyman continuum sp. survey (KLCS) (Steidel+, 2018)
J/ApJ/893/96 : CHAOS IV: NGC3184 LBT obs. & 3 other gal. abund. (Berg+, 2020)
J/A+A/654/A80 : MUSE Catalog of UV emission line measurement (Schmidt+, 2021)
http://archive.stsci.edu/hlsp/classy : CLASSY home page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/45] Internal target index number
4- 13 A10 --- Name Galaxy identifier (JHHMM+DDMM)
15- 21 F7.5 --- z [0.0016/0.182] Spectroscopic redshift
23- 27 I5 --- PID [11523/15840]? HST Program ID (1)
29- 38 A10 --- ImData Acquisition image dataset name
40- 44 F5.1 s ImExpT [0.6/510]? Acquisition image exposure time
46- 47 A2 --- f_ImExpT NA = Not applicable
49 A1 --- ImMir [AB] Acquisition image mirror
51- 53 I3 deg PA [1/355]? Position angle of aperture
55- 58 F4.2 arcsec ImGFWHM [0.1/1.42]? GFWHM along spatial axis of
acquisition image
60- 61 A2 --- f_ImGFWHM NA = Not applicable
63- 71 A9 --- SpData Spectrum dataset name
73- 77 A5 --- Grating Spectrum grating
79- 82 I4 10-10m clambda [1105/2339]? Spectrum central wavelength;
in Angstrom units
84- 84 I1 --- LP [1/4]? Spectrum lifetime position
86- 87 A2 --- f_LP NA = Not applicable
89- 93 I5 s SpExpT [356/13852]? Spectrum exposure time
95-100 F6.1 10-10m lambdaSt [966.6/1889.3]? Starting rest wavelength (2)
102-107 F6.1 10-10m lambdaEnd [1221.7/2414.6]? Ending rest wavelength (2)
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Note (1): The program IDs contain both archival and new observations.
Note (2): Of the coverage. The full extent of the contiguous wavelength
coverage is in the last row for each galaxy.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Galaxy identifier (JHHMM+DDMM)
14- 17 A4 10-10m lambda Rest-frame wavelength; Angstroms
19- 22 F4.1 km/s VHR [11.6/14.3] Nominal resolution of the VHR
spectrum in units of km/s per resolution
element (5)
24- 27 F4.1 km/s HR [14.2/17.4] Nominal resolution of the HR
spectrum in units of km/s per resolution
element (5)
29- 32 F4.1 km/s MR [38.8/47.6] Nominal resolution of the MR
spectrum in units of km/s per resolution
element (5)
34- 38 F5.1 km/s LR [96.5/119.6] Nominal resolution of the LR
spectrum in units of km/s per resolution
element (5)
40- 43 I4 km/s Res [20/128] Resolution of measured absorption
feature (6)
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Note (5): For each coadded dataset.
Note (6): Gaussian FWHM measured from the HR, Galactic extinction-corrected,
binned spectra (extension 9).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Name Galaxy identifier (JHHMM+DDMM)
12- 20 A9 --- Inst Telescope/spectrograph of optical spectrum
22- 30 A9 arcsec Ap Aperture size (1)
32- 41 A10 s ExpTime Cumulative exposure time
43- 81 A39 --- Reference Reference for the observations
83-134 A52 --- FileName Name of the FITS file in subdirectory "fits";
column added by CDS
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Note (1): These apertures are the ones used to extract the spectra used in
this work to determine the nebular properties of the CLASSY sample.
For IFU observations, the 1-dimensional spectra were extracted to
aperture-match the FUV HST/COS spectra.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/45] Internal target index number
4- 13 A10 --- Name Galaxy identifier (JHHMM+DDMM)
15- 31 A17 --- AName Alternate name(s)
33- 34 I2 h RAh Hour of Right Ascension (J2000)
36- 37 I2 min RAm Minute of Right Ascension (J2000)
39- 43 F5.2 s RAs Second of Right Ascension (J2000)
45 A1 --- DE- Sign of the Declination (J2000)
46- 47 I2 deg DEd Degree of Declination (J2000)
49- 50 I2 arcmin DEm Arcminute of Declination (J2000)
52- 56 F5.2 arcsec DEs Arcsecond of Declination (J2000)
58- 64 F7.5 --- z [0.0016/0.182] Spectroscopic redshift
66- 70 F5.2 10-17W/m2/nm F1500 [0.69/16.6] Continuum flux at 1500Å
from the CLASSY coadded spectra; in
units of 10-15erg/s/cm2/Å
72- 75 F4.2 [-] Z [6.98/8.8] Direct method oxygen
abundance (12+log (O/H))
77- 81 F5.2 [-] e_Z [0.01/11.4] Uncertainty in Z
83- 91 A9 --- r_Z Ion temperature used to determine Z
93- 95 I3 cm-3 ne [10/910] Gas-phase electron density
97- 99 I3 cm-3 e_ne [10/160] Uncertainty in ne
101- 104 F4.1 --- O32 [0.5/38] The [OIII]5007Å/[OII]3727Å
flux ratio
106- 108 F3.1 --- e_O32 [0.1/3] Uncertainty in O32
110- 114 F5.3 mag E(B-V) [0.039/0.5] Reddening value from Balmer
decrement
116- 120 F5.3 mag e_E(B-V) [0.004/0.07] Uncertainty in E (B-V)
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/45] Internal target index number
4- 13 A10 --- Name Target identifier (JHHMM+DDMM)
15- 16 I2 h RAh Hour of Right Ascension (J2000)
18- 19 I2 min RAm Minute of Right Ascension (J2000)
21- 25 F5.2 s RAs Second of Right Ascension (J2000)
27 A1 --- DE- Sign of the Declination (J2000)
28- 29 I2 deg DEd Degree of Declination (J2000)
31- 32 I2 arcmin DEm Arcminute of Declination (J2000)
34- 38 F5.2 arcsec DEs Arcsecond of Declination (J2000)
40- 46 F7.5 --- z [0.0016/0.182] Spectroscopic redshift
48- 50 I3 Mpc Dist [8/880] Luminosity distance (2)
52- 55 F4.2 arcsec r50 [0.7/7.3] Optical half light radius (3)
57- 60 F4.2 [Msun] MAper [4.9/10] COS aperture log stellar mass (4)
62- 65 F4.2 [Msun] E_MAper [0.12/0.6] Upper uncertainty in MAper
67- 70 F4.2 [Msun] e_MAper [0.09/0.5] Lower uncertainty in MAper
72- 76 F5.2 [Msun] MTot [6.2/10.1] Total log stellar mass for
entire galaxy (4)
78- 81 F4.2 [Msun] E_MTot [0.15/0.51] Upper uncertainty in MTot
83- 86 F4.2 [Msun] e_MTot [0.1/0.42] Lower uncertainty in MTot
88- 92 F5.2 [Msun/yr] SFRAper [-3.1/1.5] Within COS aperture log star
formation rate (4)
94- 97 F4.2 [Msun/yr] E_SFRAper [0.07/0.3] Upper uncertainty in SFRAper
99- 102 F4.2 [Msun/yr] e_SFRAper [0.08/0.5] Lower uncertainty in SFRAper
104- 108 F5.2 [Msun/yr] SFRTot [-2.1/1.6] Total log star formation rate
for entire galaxy (4)
110- 113 F4.2 [Msun/yr] E_SFRTot [0.07/0.7] Upper uncertainty in SFRTot
115- 118 F4.2 [Msun/yr] e_SFRTot [0.07/0.65] Lower uncertainty in SFRTot
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Note (2): Corrected for the Hubble flow using the velocity field model of
Masters (2005PhDT.........2M 2005PhDT.........2M).
Note (3): Dervied from the optical imaging (see Figure 2).
Note (4): Dervied using Beagle SED fitting.
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History:
From electronic version of the journal for Tables 2-6
Spectra (CLASSY HLSPs) downloaded from:
http://archive.stsci.edu/hlsp/classy
References:
James et al. Paper II. 2022ApJS..262...37J 2022ApJS..262...37J
Xu et al. Paper III.
Mingozzi et al. Paper IV.
Arellano-Cordova et al. Paper V. 2022ApJ...935...74A 2022ApJ...935...74A
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Sep-2022