Temperature Discrepancy With Photoionization Models of the Narrow-Line Region

Binette, L.; Martín, Montserrat Villar; Magris, G.; Martínez-Paredes, M.; Alarie, Alexandre; Ardila, Alberto Rodríguez; Villicaña-Pedraza, I.

doi:10.22201/ia.01851101p.2022.58.01.11

“…Since [Ne V] is typically 0.02-0.2 the strength of [O III], and considering the strong reddening, this nondetection is not surprising (Netzer 1990). We also attempt to decompose the [O III] λ4363 and Hγ emission lines, which may also provide corroborating evidence for excitation by an AGN (Baskin & Laor 2005;Binette et al 2022). However, given our spectral resolution, we do not achieve robust decompositions for any of the unconfirmed AGN candidates.…”

Section: Other Emission Linesmentioning

confidence: 99%

UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5

Greene,

Labbe,

Goulding

et al. 2024

ApJ

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The James Webb Space Telescope is revealing a new population of dust-reddened broad-line active galactic nuclei (AGN) at redshifts z ≳ 5. Here we present deep NIRSpec/Prism spectroscopy from the Cycle 1 Treasury program Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization (UNCOVER) of 15 AGN candidates selected to be compact, with red continua in the rest-frame optical but with blue slopes in the UV. From NIRCam photometry alone, they could have been dominated by dusty star formation or an AGN. Here we show that the majority of the compact red sources in UNCOVER are dust-reddened AGN: 60% show definitive evidence for broad-line Hα with a FWHM > 2000 km s −1, 20% of the current data are inconclusive, and 20% are brown dwarf stars. We propose an updated photometric criterion to select red z > 5 AGN that excludes brown dwarfs and is expected to yield >80% AGN. Remarkably, among all z phot > 5 galaxies with F277W – F444W > 1 in UNCOVER at least 33% are AGN regardless of compactness, climbing to at least 80% AGN for sources with F277W – F444W > 1.6. The confirmed AGN have black hole masses of 107–109 M ⊙. While their UV luminosities (−16 > M UV > −20 AB mag) are low compared to UV-selected AGN at these epochs, consistent with percent-level scattered AGN light or low levels of unobscured star formation, the inferred bolometric luminosities are typical of 107–109 M ⊙ black holes radiating at ∼10%–40% the Eddington limit. The number densities are surprisingly high at ∼10−5 Mpc−3 mag−1, 100 times more common than the faintest UV-selected quasars, while accounting for ∼1% of the UV-selected galaxies. While their UV faintness suggests they may not contribute strongly to reionization, their ubiquity poses challenges to models of black hole growth.

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“…Extreme values of RO3 have already been reported in recent JWST spectra; for example, a z = 8.5 galaxy presented in Katz et al (2023) shows an RO3 of 0.048 when corrected for dust. Elevated RO3s are not new and have been discussed in the context of low-z Seyfert galaxies (e.g., Koski & Osterbrock 1976;Osterbrock 1978;Ferland & Netzer 1983;Dopita & Sutherland 1995;Nagao et al 2001;Baskin & Laor 2005;Binette et al 2022). In fact, the photoionization models of Baskin & Laor (2005) suggest that it is possible to reach the required densities and temperatures to produce extreme RO3s within the NLR around an AGN.…”

Section: Ionization Mechanismsmentioning

confidence: 99%

UNCOVER: A NIRSpec Identification of a Broad-line AGN at z = 8.50

Kokorev,

Fujimoto,

Labbe

et al. 2023

ApJL

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Deep observations with the James Webb Space Telescope (JWST) have revealed an emerging population of red pointlike sources that could provide a link between the postulated supermassive black hole seeds and observed quasars. In this work, we present a JWST/NIRSpec spectrum from the JWST Cycle 1 UNCOVER Treasury survey of a massive accreting black hole at z = 8.50 displaying a clear broad-line component as inferred from the Hβ line with FWHM = 3439 ± 413 km s−1, typical of the broad-line region of an active galactic nucleus (AGN). The AGN nature of this object is further supported by high ionization, as inferred from emission lines, and a point-source morphology. We compute a black hole mass of log 10 ( M BH / M ⊙ ) = 8.17 ± 0.42 and a bolometric luminosity of L bol ∼ 6.6 × 1045 erg s−1. These values imply that our object is accreting at ∼40% of the Eddington limit. Detailed modeling of the spectral energy distribution in the optical and near-infrared, together with constraints from ALMA, indicate an upper limit on the stellar mass of log 10 ( M * / M ⊙ ) < 8.7 , which would lead to an unprecedented ratio of black hole to host mass of at least ∼30%. This is orders of magnitude higher compared to the local QSOs but consistent with recent AGN studies at high redshift with JWST. This finding suggests that a nonnegligible fraction of supermassive black holes either started out from massive seeds and/or grew at a super-Eddington rate at high redshift. Given the predicted number densities of high-z faint AGN, future NIRSpec observations of larger samples will allow us to further investigate galaxy–black hole coevolution in the early Universe.

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First insights into the ISM at z > 8 with JWST: possible physical implications of a high [O iii] λ4363/[O iii] λ5007

Katz

¹

,

Saxena

²

,

Cameron

³

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We present a detailed analysis of the rest-frame optical emission line ratios for three spectroscopically confirmed galaxies at z > 7.5. The galaxies were identified in the James Webb Space Telescope (JWST) Early Release Observations field SMACS J0723.3−7327. By quantitatively comparing Balmer and oxygen line ratios of these galaxies with various low-redshift “analogue” populations (e.g. Green Peas, Blueberries, etc.), we show that no single analogue population captures the diversity of line ratios of all three galaxies observed at z > 7.5. We find that S06355 at z = 7.67 and S10612 at z = 7.66 are similar to local Green Peas and Blueberries. In contrast, S04590 at z = 8.50 appears to be significantly different from the other two galaxies, most resembling extremely low-metallicity systems in the local Universe. Perhaps the most striking spectral feature in S04590 is the curiously high [O III] λ4363/[O III] λ5007 ratio (RO3) of 0.047 (or 0.059 when dust-corrected), implying either extremely high electron temperatures, >3 × 104 K, or gas densities >104 cm−3. Observed line ratios indicate that this galaxy is unlikely to host an AGN. Using photoionization modelling, we show that the inclusion of high-mass X-ray binaries or a high cosmic ray background in addition to a young, low-metallicity stellar population can provide the additional heating necessary to explain the observed high RO3 while remaining consistent with other observed line ratios. Our models represent a first step at accurately characterising the dominant sources of photoionization and heating at very high redshifts, demonstrating that non-thermal processes may become important as we probe deeper into the Epoch of Reionization.

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Temperature Discrepancy With Photoionization Models of the Narrow-Line Region

Cited by 4 publications

References 38 publications

UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5

UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5

UNCOVER: A NIRSpec Identification of a Broad-line AGN at z = 8.50

First insights into the ISM at z > 8 with JWST: possible physical implications of a high [O iii] λ4363/[O iii] λ5007

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Temperature Discrepancy With Photoionization Models of the Narrow-Line Region

Cited by 4 publications

References 38 publications

UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5

UNCOVER Spectroscopy Confirms the Surprising Ubiquity of Active Galactic Nuclei in Red Sources at z > 5

UNCOVER: A NIRSpec Identification of a Broad-line AGN at z = 8.50

First insights into the ISM at z &gt; 8 with JWST: possible physical implications of a high [O iii] λ4363/[O iii] λ5007

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First insights into the ISM at z > 8 with JWST: possible physical implications of a high [O iii] λ4363/[O iii] λ5007