On the Escape of Ionizing Radiation from Starbursts

By Tim Heckman, K. Sembach, G. Meurer, C. Leitherer, D. Calzetti, Crystal L. Martin. 2001

152 citations recorded by the source corpus.

Far-ultraviolet spectra obtained with FUSE show that the strong C II λ1036 interstellar absorption line is essentially black in five of the UV-brightest local starburst galaxies. Because the opacity of the neutral ISM below the Lyman edge will be significantly larger than in the C II line, these data provide strong constraints on the escape of ionizing radiation from these starbursts. Interpreted as a uniform, absorbing slab, the implied optical depth at the Lyman edge is huge (τ0 ≥ 102). Alternatively, the areal covering factor of opaque material is typically ≥94%. Thus, the fraction of ionizing stellar photons that escape the ISM of each galaxy is small: our conservative estimates typically yield fesc ≤ 6%. Inclusion of extinction due to dust will further decrease fesc. An analogous analysis of the rest-UV spectrum of the star-forming galaxy MS 1512-cB58 at z = 2.7 leads to similar constraints on fesc. These new results agree with the constraints provided by direct observations below the Lyman edge in a few other local starbursts. However, they differ from the recently reported properties of star-forming galaxies at z ≥ 3. We assess the idea that the strong galactic winds seen in many powerful starbursts clear channels through their neutral ISM. We show empirically that such outflows may be a necessary—but not sufficient—part of the process of creating a relatively porous ISM. We note that observations will soon document the cosmic evolution in the contribution of star-forming galaxies to the metagalactic ionizing background, with important implications for the evolution of the IGM.

Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering, Instrumentation

View Paper: https://www.semanticscholar.org/paper/379ba2981eabb7b2c7a5c59879a01d740a0aa6c2

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In Astronomy and Astrophysics

1. L. Hernquist
2. P. Hopkins
3. R. Dav'e
4. Volker Springel
5. C. Conroy
6. A. Dekel
7. Simon D. M. White
8. R. Somerville

In Electrical and Electronic Engineering

1. Simon D. M. White
2. C. Steidel
3. A. Dekel
4. A. Meiksin
5. M. Pettini
6. T. Heckman
7. Renyue Cen
8. G. Kauffmann

In Instrumentation

1. L. Hernquist
2. P. Hopkins
3. R. Dav'e
4. C. Conroy
5. A. Dekel
6. Simon D. M. White
7. Volker Springel
8. R. Somerville

Citations in the corpus

• Using Lyman-α to detect galaxies that leak Lyman continuum (2014, background): “…Telescope (HUT) and Far Ultraviolet Spectroscopic Explorer (FUSE) have reported a large number of upper limits (e.g. Leitherer et al. 1995; Heckman et al. 2001; Deharveng et al. 2001; Grimes et al. 2009) and only a small number of weak detections with escape fractions of only a few…”
• The Survey for Ionization in Neutral Gas Galaxies. III. Diffuse, Warm Ionized Medium and Escape of Ionizing Radiation (2007, result): “We note that although previous studies reported that starburst galaxies are optically thick to ionizing photons (e.g., Heckman et al. 2001; Leitherer et al. 1995), Shapley et al. (2006) recently reported un- ambiguous detection of Lyman continuum radiation from individual galaxies at z 3, and…”
• THE SYSTEMATIC PROPERTIES OF THE WARM PHASE OF STARBURST-DRIVEN GALACTIC WINDS (2015, background): “The first is a sample of 19 galaxies observed with the Far Ultraviolet Spectroscopic Explore (FUSE), and was previously investigated by Grimes et al. (2009: hereafter G09) and Heckman et al. (2001).”
• The Fate of the First Galaxies. II. Effects of Radiative Feedback (2001, result): “Observations of 〈fesc〉 in nearby starburst galaxies find values of 〈fesc〉 < ∼ 10% (Leitherer et al. 1995; Hurwitz, Jelinsky, & Dixon 1997; Heckman et al. 2001; Deharveng et al. 2001), in agreement with theoretical studies (Dove, Shull, & Ferrara 2000).”
• Rest-Frame Ultraviolet Spectra of z ∼ 3 Lyman Break Galaxies (2003, background): “If the radiation field is dominated by the spectrum of hot stars, rather than an AGN, O VI is likely to arise in collisionally ionized gas, indicating the presence of an even hotter phase with T >∼ 10 5K (Heckman et al. 2001b).”
• Constraints on Warm Dark Matter from Cosmological Reionization (2001, methodology): “On the other hand, Heckman et al. (2001) applied a di†erent method based on interstellar absorption lines and found a very low in severalfesc \ 6%local starburst galaxies and one such galaxy at z\ 2.7.”
• New Observations of the Interstellar Medium in the Lyman Break Galaxy MS 1512–cB58 (2001, methodology): “It is also likely to produce regions where the gas is optically thin to Lyman continuum photons, which can thus escape into the IGM and contribute to the ionizing background (Steidel, Pettini, & Adelberger 2001).”
• EXTREME FEEDBACK AND THE EPOCH OF REIONIZATION: CLUES IN THE LOCAL UNIVERSE (2011, methodology): “…made to measure this escape-fraction in star-forming galaxies at low-redshift (Leitherer et al. 1995; Hurwitz et al. 1997; Deharveng et al. 2001; Heckman et al. 2001 - hereafter H01; Bergvall et al. 2006; Grimes et al. 2009 - hereafter G09), intermediate redshift (Malkan et al. 2003, Siana et…”
• The Large-Scale Bipolar Wind in the Galactic Center (2002, background): “Furthermore, hot wind gas detected in [O vi] is found to be moving more rapidly than the cool gas (Heckman et al. 2001).”
• Cosmic reionization by stellar sources: population III stars (2003, methodology): “…0.10) that have been C© 2003 RAS, MNRAS 344, 607–624 Downloaded from https://academic.oup.com/mnras/article-abstract/344/2/607/1126957 by guest on 28 July 2018 observationally deduced from z < 3 starburst galaxies (see Leitherer et al. 1995; Hurwitz, Jenlinsky & Dixon 1997; Heckman et al. 2001).”
• THE ORIGIN AND OPTICAL DEPTH OF IONIZING RADIATION IN THE “GREEN PEA” GALAXIES (2013, background): “At low redshift, observations of star-forming galaxies give upper limits on the escape fraction of only a few percent (e.g., Leitherer et al. 1995; Heckman et al. 2001; Siana et al. 2010).”
• An empirical calibration of star formation rate estimators (2001, background): “Heckman et al (2001) show that in five of the UV brightest local starburst galaxies the fraction of photons escaping is less than about 6% while Steidel, Pettini and Adelberger (2001) claim a higher escape fraction.”
• Escape of Ionizing Radiation from High-Redshift Galaxies (2007, background): “Recent empirical measurements of the escape fraction from normal galaxies in the local universe (Leitherer et al. 1995; Heckman et al. 2001; Bergvall et al. 2006) and at high redshifts (Giallongo et al. 2002; Fernández-Soto et al. 2003; 1 Particle Astrophysics Center, Fermi National…”
• Escape of Lyman continuum radiation from local galaxies - Detection of leakage from the young starburst Tol 1247-232 (2013, methodology): “This method was introduced in Heckman et al. (2001), and is based on the expectation of a residual flux in the low ionization interstellar absorption line C λ1036 Å if the galaxy is leaking ionizing photons.”
• IONIZING PHOTON ESCAPE FRACTIONS FROM HIGH-REDSHIFT DWARF GALAXIES (2008, unknown): “Heckman et al. (2001) found fesc ≤ 0.06.”
• The Universe Was Reionized Twice (2002, background): “Heckman et al. (2001) give fes 0:06 for local starburst galaxies.”
• Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies (2017, background): “…Universe, extremely few LyC leaking galaxies have been found, all exhibiting low escape fractions fesc ∼ 1−10% (Bergvall et al. 2006; Leitet et al. 2013; Izotov et al. 2016, see also Heckman et al. (2011)), and for some other candidates, only upper limits could be secured (Heckman et al. 2001).”
• Rapid Reionization by the Oligarchs: The Case for Massive, UV-bright, Star-forming Galaxies with High Escape Fractions (2019, background): “Heckman et al. (2001) explicitly link fesc to a critical value of SSFR ~ - -M0.”
• The physical properties of star-forming galaxies in the low-redshift universe (2003, background): “Even local starburst galaxies have escape fractions <10 per cent (Leitherer et al. 1995; Heckman et al. 2001, see also CL01).”