The Low-Redshift Lyman Continuum Survey II: New Insights into LyC Diagnostics

Flury, Sophia R.; Jaskot, Anne E.; Ferguson, Harry C.; Worseck, Gabor; Makan, Kirill; Chisholm, John; Saldana-Lopez, Alberto; Schaerer, Daniel; McCandliss, Stephan; Wang, Bingjie; Ford, N. M.; Oey, M. S.; Heckman, Timothy; Ji, Zhiyuan; Giavalisco, Mauro; Amorin, Ricardo; Atek, Hakim; Blaizot, Jeremy; Borthakur, Sanchayeeta; Carr, Cody; Castellano, Marco; Cristiani, Stefano; de Barros, Stephane; Dickinson, Mark; Finkelstein, Steven L.; Fleming, Brian; Fontanot, Fabio; Garel, Thibault; Grazian, Andrea; Hayes, Matthew; Henry, Alaina; Mauerhofer, Valentin; Micheva, Genoveva; Ostlin, Goran; Papovich, Casey; Pentericci, Laura; Ravindranath, Swara; Rosdahl, Joakim; Rutkowski, Michael; Santini, Paola; Scarlata, Claudia; Teplitz, Harry; Thuan, Trinh; Trebitsch, Maxime; Vanzella, Eros; Verhamme, Anne; Xu, Xinfeng

doi:10.48550/arxiv.2203.15649

Cited by 3 publications

(7 citation statements)

References 105 publications

(184 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, our Mg observations suggest that the scatter in these relations are largely driven by spatial variations of dust and neutral gas. This order of magnitude scatter is fairly similar to the scatter that is observed in the indirect LyC trends of Flury et al 2022b. Recovering any trends from this amount of scatter would require very large samples to average over the spatial variations.…”

Section: Variations Of Indirect Tracers Between Aperturessupporting

confidence: 65%

“…Recent observations have successfully found local galaxies that emit ionizing photons. These observations have found escape fractions between 0-73%, with a large scatter in many of the classically expected diagnostics -like [O ]𝜆5007/[O ]𝜆𝜆3727, 3729 and H𝛽 equivalent widths (Naidu et al 2018;Fletcher et al 2019;Izotov et al 2021;Flury et al 2022b). To reconcile these discrepancies with a complete understanding of reionization would require a measurement of the volume-averaged escape fraction from LyC leakers.…”

Section: Variations Of Indirect Tracers Between Aperturesmentioning

confidence: 98%

“…Thus far, these methods have included Ly𝛼 emission properties (Verhamme et al 2015;Rivera-Thorsen et al 2017;Izotov et al 2018;Gazagnes et al 2021;Izotov et al 2021;Flury et al 2022b), ISM absorption properties (Reddy et al 2016;Gazagnes et al 2018;Chisholm et al 2018;Steidel et al 2018;Saldana-Lopez et al 2022), resonant emission lines (Henry et al 2018;Chisholm et al 2020;Witstok et al 2021;Schaerer et al 2022;Izotov et al 2022;Xu et al 2022), and optical emission line ratios (Nakajima & Ouchi 2014;Oey et al 2014;Wang et al 2019;Flury et al 2022b). However, from Flury et al 2022b, many of these indirect indicators have substantial scatter, making it challenging to indirectly infer the LyC escape fraction from single observations. The large scatter in escape fractions has been explored in simulations and connected to large spatial scatter in f esc (LyC) (Trebitsch et al 2017;Rosdahl et al 2018;Mauerhofer et al 2021).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Understanding the spatial variation of Mg ii and ionizing photon escape in a local LyC leaker

Seive

Chisholm

Leclercq

et al. 2022

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

Ionizing photons must have escaped from high-redshift galaxies, but the neutral high-redshift intergalactic medium makes it unlikely to directly detect these photons during the Epoch of Reionization. Indirect methods of studying ionizing photon escape fractions present a way to infer how the first galaxies may have reionized the universe. Here, we use HET/LRS2 observations of J0919+4906, a confirmed z≈0.4 emitter of ionizing photons to achieve spatially resolved (12.5 kpc in diameter) spectroscopy of Mg iiλ2796, Mg iiλ2803, [O ii]λλ3727, 3729 , [Ne iii]λ3869, Hγ, [O iii]λ4363, Hβ, [O iii]λ4959, [O iii]λ5007, and Hα. From these data we measure Mg ii emission, which is a promising indirect tracer of ionizing photons, along with nebular ionization and dust attenuation in multiple spatially-resolved apertures. We find that J0919+4906 has significant spatial variation in its Mg ii escape and thus ionizing photon escape fraction. Combining our observations with photoionization models, we find that the regions with the largest relative Mg ii emission and Mg ii escape fractions have the highest ionization and lowest dust attenuation. Some regions have an escape fraction that matches that required by models to reionize the early universe, while other regions do not. We observe a factor of 36 spatial variation in the inferred LyC escape fraction, which is similar to recently observed statistical samples of indirect tracers of ionizing photon escape fractions. These observations suggest that spatial variations in neutral gas properties lead to large variations in the measured LyC escape fractions. Our results suggest that single sightline observations may not trace the volume-averaged escape fraction of ionizing photons.

show abstract

Section: Variations Of Indirect Tracers Between Aperturessupporting

confidence: 65%

Section: Variations Of Indirect Tracers Between Aperturesmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Understanding the spatial variation of Mg ii and ionizing photon escape in a local LyC leaker

Seive

Chisholm

Leclercq

et al. 2022

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

show abstract

“…We evaluate LCE and f esc LyC diagnostics in companion papers (Wang et al 2021;Flury et al 2022). We also analyze the UV absorption lines (Saldana-Lopez et al 2022) and SED parameters (Z.…”

Section: Discussionmentioning

confidence: 99%

“…From our measurements of the LyC flux, we provide estimates of f esc LyC for our sample (Section 6). Companion papers present our initial tests of indirect LyC diagnostics (Flury et al 2022;Saldana-Lopez et al 2022;Wang et al 2021). Throughout this paper, we assume H 0 = 70 km s −1 Mpc −1 , Ω m = 0.3, and Ω Λ = 0.7.…”

Section: Introductionmentioning

confidence: 99%

The Low-redshift Lyman Continuum Survey. I. New, Diverse Local Lyman Continuum Emitters

Flury

Jaskot

Ferguson

et al. 2022

ApJS

Self Cite

110

117

View full text Add to dashboard Cite

The origins of Lyman continuum (LyC) photons responsible for the reionization of the universe are as of yet unknown and highly contested. Detecting LyC photons from the Epoch of Reionization is not possible due to absorption by the intergalactic medium, which has prompted the development of several indirect diagnostics to infer the rate at which galaxies contribute LyC photons to reionize the universe by studying lower-redshift analogs. We present the Low-redshift Lyman Continuum Survey (LzLCS) comprising measurements made with the Hubble Space Telescope Cosmic Origins Spectrograph for a z = 0.2–0.4 sample of 66 galaxies. After careful processing of the far-UV spectra, we obtain a total of 35 Lyman continuum emitters (LCEs) detected with 97.725% confidence, nearly tripling the number of known local LCEs. We estimate escape fractions from the detected LyC flux and upper limits on the undetected LyC flux, finding a range of LyC escape fractions up to 50%. Of the 35 LzLCS LCEs, 12 have LyC escape fractions greater than 5%, more than doubling the number of known local LCEs with cosmologically relevant LyC escape.

show abstract

Spectral Shapes of the Lya Emission from Galaxies. II. the influence of stellar properties and nebular conditions on the emergent Lya profiles

Hayes¹,

Runnholm²,

Scarlata³

et al. 2023

Preprint

View full text Add to dashboard Cite

We demonstrate how the stellar and nebular conditions in star-forming galaxies modulate the emission and spectral profile of H Ly𝛼 emission line. We examine the net Ly𝛼 output, kinematics, and in particular emission of blue-shifted Ly𝛼 radiation, using spectroscopy from with the Cosmic Origins Spectrograph on HST, giving a sample of 87 galaxies at redshift 𝑧 = 0.05 − 0.44. We contrast the Ly𝛼 spectral measurements with properties of the ionized gas (from optical spectra) and stars (from stellar modeling). We demonstrate correlations of unprecedented strength between the Ly𝛼 escape fraction (and equivalent width) and the ionization parameter (𝑝 ≈ 10 −15 ). The relative contribution of blue-shifted emission to the total Ly𝛼 also increases from ≈ 0 to ≈ 40 % over the range of O 32 ratios (𝑝 ≈ 10 −6 ). We also find particularly strong correlations with estimators of stellar age and nebular abundance, and weaker correlations regarding thermodynamic variables. Low ionization stage absorption lines suggest the Ly𝛼 emission and line profile are predominantly governed by the column of absorbing gas near zero velocity. Simultaneous multi-parametric analysis over many variables shows we can predict 80 % of the variance on Ly𝛼 luminosity, and ∼ 50 % on the EW. We determine the most crucial predictive variables, finding that for tracers of the ionization state and H𝛽 luminosity dominate the luminosity prediction whereas the Ly𝛼 EW is best predicted by H𝛽 EW and the H𝛼/H𝛽 ratio. We discuss our results with reference to high redshift observations, focussing upon the use of Ly𝛼 to probe the nebular conditions in high-𝑧 galaxies and cosmic reionization.

show abstract

The Low-Redshift Lyman Continuum Survey II: New Insights into LyC Diagnostics

Cited by 3 publications

References 105 publications

Understanding the spatial variation of Mg ii and ionizing photon escape in a local LyC leaker

Understanding the spatial variation of Mg ii and ionizing photon escape in a local LyC leaker

The Low-redshift Lyman Continuum Survey. I. New, Diverse Local Lyman Continuum Emitters

Spectral Shapes of the Lya Emission from Galaxies. II. the influence of stellar properties and nebular conditions on the emergent Lya profiles

Contact Info

Product

Resources

About