The COS Legacy Archive Spectroscopy Survey (CLASSY) Treasury Atlas*

Berg, Danielle A.; James, Bethan L.; King, Teagan; Mcdonald, Meaghan; Chen, Zuyi; Chisholm, John; Heckman, Timothy M.; Martin, Crystal L.; Stark, Dan; Team, The Classy; _, _; Aloisi, Alessandra; Amorín, R.; Arellano-Córdova, K. Z.; Bayliss, M.; Bordoloi, Rongmon; Brinchmann, Jarle; Charlot, S.; Chevallard, Jacopo; Clark, Ilyse; Erb, Dawn K.; Feltre, Anna; Hayes, Matthew; Henry, Alaina; Hernández, Svea; Jaskot, Anne; Jones, Tucker; Kewley, Lisa J.; Kumari, Nimisha; Leitherer, Claus; Llerena, Mario; Maseda, Michael V.; Mingozzi, Matilde; Nanayakkara, Themiya; Ouchi, Masami; Plat, Adèle; Pogge, Richard W.; Ravindranath, Swara; Rigby, Jane; Sanders, Ryan L.; Scarlata, Claudia; Senchyna, Peter; Skillman, Evan D.; Steidel, C. C.; Strom, Allison L.; Sugahara, Yuma; Wilkins, Stephen M.; Wofford, Aida; Xu, Xinfeng

doi:10.3847/1538-4365/ac6c03

Cited by 66 publications

(98 citation statements)

References 150 publications

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“…The ancillary optical spectra of CLASSY comprise observations of APO/SDSS (Eisenstein et al 2011) of 38 out of 45 objects, and multiple observations of Keck/Echellette Spectrograph and Imager (ESI) and VLT/MUSE IFU (R. L. Sanders et al in preparation;Senchyna et al 2019) for a small subsample of CLASSY galaxies (Berg et al 2022). In addition, seven CLASSY galaxies were observed using long-slit spectroscopy with the Large Binocular Telescope (LBT; Hill et al 2010) to ensure the accurate measurement of the physical properties of these galaxies (see Section 2.1).…”

Section: Optical Spectramentioning

confidence: 99%

“…In addition, seven CLASSY galaxies were observed using long-slit spectroscopy with the Large Binocular Telescope (LBT; Hill et al 2010) to ensure the accurate measurement of the physical properties of these galaxies (see Section 2.1). In summary, the CLASSY sample is fully covered by optical spectra for different observational sets available (Berg et al 2022;James et al 2022) and follow-up observations. The telescope and instruments used for the optical observations in this paper are listed in Table 1.…”

Section: Optical Spectramentioning

confidence: 99%

“…In this work, we have selected the 12 star-forming galaxies from the CLASSY sample having optical spectra with multiple aperture sizes (1 0-3 0), observational modes (long-slit and IFU model), and spectral resolutions. In particular, the IFU data allow us to map the gas emission using different aperture sizes, which provides a better comparison between the different observations of this sample, e.g., to analyze the results obtained using the same aperture as in HST/COS (Berg et al 2022;James et al 2022).…”

Section: Optical Spectramentioning

confidence: 99%

“…For comparison purposes, the LBT/MODS slit has been truncated (1″ × 2 5) to show the extraction region of the observation. The slit was centered on the highest surface brightness knots of optical emission based on SDSS r-band images, following the position of the HST/COS aperture of each CLASSY galaxy in the UV (Berg et al 2022).…”

Section: Lbt/mods Observationsmentioning

confidence: 99%

“…Recently, Berg et al (2022;hereafter, Paper I) presented the COS Legacy Archive Spectroscopic SurveY (CLASSY) treasury, obtained with Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope (HST). CLASSY comprises a sample of 45 local (0.002 < z < 0.182) starforming galaxies with high-resolution (R ∼ 15, 000) farultraviolet (FUV) COS spectra and moderate-resolution (R ∼ 2000) optical spectra.…”

Section: Introductionmentioning

confidence: 99%

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CLASSY V: The Impact of Aperture Effects on the Inferred Nebular Properties of Local Star-forming Galaxies

Arellano-Córdova

Mingozzi

Berg

et al. 2022

ApJ

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Strong nebular emission lines are an important diagnostic tool for tracing the evolution of star-forming galaxies across cosmic time. However, different observational setups can affect these lines, and the derivation of the physical nebular properties. We analyze 12 local star-forming galaxies from the COS Legacy Spectroscopy SurveY (CLASSY) to assess the impact of using different aperture combinations on the determination of the physical conditions and gas-phase metallicity. We compare optical spectra observed with the Sloan Digital Sky Survey Data Release aperture, which has a 3″ diameter similar to COS, IFU, and long-slit spectra, including new LBT/MODS observations of five CLASSY galaxies. We calculate the reddening, electron densities and temperatures, metallicities, star formation rates, and equivalent widths (EWs). We find that measurements of the electron densities and temperatures, and metallicity remained roughly constant with aperture size, indicating that the gas conditions are relatively uniform for this sample. However, using IFU observations of three galaxies, we find that the E(B − V) values derived from the Balmer ratios decrease (by up to 53%) with increasing aperture size. The values change most significantly in the center of the galaxies, and level out near the COS aperture diameter of 2.″5. We examine the relative contributions from the gas and stars using the Hα and [O iii] λ5007 EWs as a function of aperture light fraction, but find little to no variations within a given galaxy. These results imply that the optical spectra provide nebular properties appropriate for the far-UV CLASSY spectra, even when narrow 1.″0 long-slit observations are used.

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Section: Optical Spectramentioning

confidence: 99%

Section: Optical Spectramentioning

confidence: 99%

Section: Optical Spectramentioning

confidence: 99%

Section: Lbt/mods Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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CLASSY V: The Impact of Aperture Effects on the Inferred Nebular Properties of Local Star-forming Galaxies

Arellano-Córdova

Mingozzi

Berg

et al. 2022

ApJ

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A small and vigorous black hole in the early Universe

Maiolino,

Scholtz,

Witstok

et al. 2024

Nature

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Several theories have been proposed to describe the formation of black hole seeds in the early Universe and to explain the emergence of very massive black holes observed in the first thousand million years after the Big Bang1–3. Models consider different seeding and accretion scenarios4–7, which require the detection and characterization of black holes in the first few hundred million years after the Big Bang to be validated. Here we present an extensive analysis of the JWST-NIRSpec spectrum of GN-z11, an exceptionally luminous galaxy at z = 10.6, revealing the detection of the [Neiv]λ2423 and CII*λ1335 transitions (typical of active galactic nuclei), as well as semi-forbidden nebular lines tracing gas densities higher than 109 cm−3, typical of the broad line region of active galactic nuclei. These spectral features indicate that GN-z11 hosts an accreting black hole. The spectrum also reveals a deep and blueshifted CIVλ1549 absorption trough, tracing an outflow with velocity 800−1,000 km s−1, probably driven by the active galactic nucleus. Assuming local virial relations, we derive a black hole mass of $$\log ({M}_{{\rm{BH}}}/{M}_{\odot })=6.2\pm 0.3$$ log ( M BH / M ⊙ ) = 6.2 ± 0.3 , accreting at about five times the Eddington rate. These properties are consistent with both heavy seeds scenarios and scenarios considering intermediate and light seeds experiencing episodic super-Eddington phases. Our finding explains the high luminosity of GN-z11 and can also provide an explanation for its exceptionally high nitrogen abundance.

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X-Shooting ULLYSES: Massive stars at low metallicity

Vink,

Mehner,

Crowther

et al. 2023

A&A

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Observations of individual massive stars, super-luminous supernovae, gamma-ray bursts, and gravitational wave events involving spectacular black hole mergers indicate that the low-metallicity Universe is fundamentally different from our own Galaxy. Many transient phenomena will remain enigmatic until we achieve a firm understanding of the physics and evolution of massive stars at low metallicity (Z). The Hubble Space Telescope has devoted 500 orbits to observing ∼250 massive stars at low Z in the ultraviolet (UV) with the COS and STIS spectrographs under the ULLYSES programme. The complementary X-Shooting ULLYSES (XShootU) project provides an enhanced legacy value with high-quality optical and near-infrared spectra obtained with the wide-wavelength coverage X-shooter spectrograph at ESO’s Very Large Telescope. We present an overview of the XShootU project, showing that combining ULLYSES UV and XShootU optical spectra is critical for the uniform determination of stellar parameters such as effective temperature, surface gravity, luminosity, and abundances, as well as wind properties such as mass-loss rates as a function of Z. As uncertainties in stellar and wind parameters percolate into many adjacent areas of astrophysics, the data and modelling of the XShootU project is expected to be a game changer for our physical understanding of massive stars at low Z. To be able to confidently interpret James Webb Space Telescope spectra of the first stellar generations, the individual spectra of low-Z stars need to be understood, which is exactly where XShootU can deliver.

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The COS Legacy Archive Spectroscopy Survey (CLASSY) Treasury Atlas*

Cited by 66 publications

References 150 publications

CLASSY V: The Impact of Aperture Effects on the Inferred Nebular Properties of Local Star-forming Galaxies

CLASSY V: The Impact of Aperture Effects on the Inferred Nebular Properties of Local Star-forming Galaxies

A small and vigorous black hole in the early Universe

X-Shooting ULLYSES: Massive stars at low metallicity

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