EXTREME FEEDBACK AND THE EPOCH OF REIONIZATION: CLUES IN THE LOCAL UNIVERSE

By Timothy M. Heckman, S. Borthakur, R. Overzier, G. Kauffmann, A. Basu-Zych, C. Leitherer, K. Sembach, D. C. Martin, R. Rich, David Schiminovich and 1 more. 2011

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The source responsible for reionizing the universe at z>6 remains uncertain. While an energetically adequate population of star-forming galaxies may be in place, it is unknown whether a large enough fraction of their ionizing radiation can escape into the intergalactic medium. Attempts to measure this escape fraction in intensely star-forming galaxies at lower redshifts have largely yielded upper limits. In this paper, we present new Hubble Space Telescope Cosmic Origins Spectrograph and archival Far-Ultraviolet Spectroscopic Explorer (FUSE) far-UV spectroscopy of a sample of 11 Lyman Break Analogs (LBAs), a rare population of local galaxies that strongly resemble the high-z Lyman Break galaxies. We combine these data with Sloan Digital Sky Survey optical spectra and Spitzer photometry. We also analyze archival FUSE observations of 15 typical UV-bright local starbursts. We find evidence of small covering factors for optically thick neutral gas in three cases. This is based on two independent pieces of evidence: a significant residual intensity in the cores of the strongest interstellar absorption-lines tracing neutral gas and a small ratio of extinction-corrected Hα to UV plus far-IR luminosities. These objects represent three of the four LBAs that contain a young, very compact (∼102 pc), and highly massive (∼109 M☉) dominant central object (DCO). These three objects also differ from the other galaxies in showing a significant amount of blueshifted Lyα emission, which may be related to the low covering factor of neutral gas. All four LBAs with DCOs in our sample show extremely high velocity outflows of interstellar gas, with line centroids blueshifted by about 700 km s−1 and maximum outflow velocities reaching at least 1500 km s−1. We show that these properties are consistent with an outflow driven by a powerful starburst that is exceptionally compact. We speculate that such extreme feedback may be required to enable the escape of ionizing radiation from star-forming galaxies.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d9a53559759ec4f605d6c2340cde99b2a8d163af

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Citations in the corpus

Spectroscopic confirmation of four metal-poor galaxies at z = 10.3–13.2 (2022, methodology): “We fit with a picket fence model [allowing for clear sight-lines to the stars through the outer neutral envelopes of birth clouds 59 ].”
Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population (2014, background): “…investigation of the possibility that star formation drives the outflows could be achieved using high resolution optical-continuumimaging to measure the SFR surface densities in our targets (e.g., Murray et al. 2011; Heckman et al. 2011; Diamond-Stanic et al. 2012; Förster Schreiber et al. 2013).”
An extreme [O III] emitter at z = 3.2: a low metallicity Lyman continuum source (2015, background): “The star formation activity confined in a small physical volume can also favor the escape of ionizing radiation (e.g., Heckman et al. 2011; Borthakur et al. 2014).”
Rapid Reionization by the Oligarchs: The Case for Massive, UV-bright, Star-forming Galaxies with High Escape Fractions (2019, background): “3 (Heckman et al. 2011; Borthakur et al. 2014; Izotov et al. 2016a, 2016b, 2018a, 2018b; Leitherer et al. 2016), the HST/F336W, HST/F275W, and ground-based UV spectrograph sources at z∼2–4 (de Barros et al. 2016; Shapley et al. 2016; Vanzella et al. 2016, 2018; Bian et al. 2017; Naidu et al. 2017,…”
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).”
Lyα Emitting Galaxies as a Probe of Reionisation (2014, background): “…by Jones et al. (2013) show that the maximum low-ionisation covering fraction is 100% in only 2 out of 8 of their z > 2 galaxies (also see Heckman et al. 2011, who find evidence for a low covering factor of optically thick, neutral gas in a small fraction of lower redshift Lyman Break…”
Ionization state of inter-stellar medium in galaxies: evolution, SFR-M * -Z dependence, and ionizing photon escape (2013, background): “We note that Haro 11 can be classified as an LBA (Heckman et al. 2011).”
Lyman-α spectral properties of five newly discovered Lyman continuum emitters (2016, methodology): “In practice we have been able to compile measurements for 12 GPs (Jaskot & Oey 2014; Henry et al. 2015; Yang et al. 2016), and 8 LBAs (Heckman et al. 2011).”
Escape of Lyman continuum radiation from local galaxies - Detection of leakage from the young starburst Tol 1247-232 (2013, background): “7, that a significant residual intensity in the core of the C λ1036 Å absorption line is a necessary but not sufficient condition for the escape of ionizing radiation (Heckman et al. 2011).”
The First Billion Years project: the escape fraction of ionizing photons in the epoch of reionization (2015, background): “Except for two objects (Leitet et al. 2011, 2013), in the local Universe no ionising radiation has been detected directly (Leitherer et al. 1995; Deharveng et al. 2001), although some objects show indirect evidence of photon leakage (Heckman et al. 2011; Zastrow et al. 2011).”
Using Lyman-α to detect galaxies that leak Lyman continuum (2014, methodology): “Our sample was selected from Bergvall et al. (2006), Heckman et al. (2011), Leitet et al. (2013).”
Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies (2016, background): “For comparison, Heckman et al. (2011) examined so-called Lyman-break analogs (LBAs) and suggested that a subset of them, those with a compact massive (∼ 109 M ) dominant central object, could be LyC leakers.”
THE MULTIPHASE STRUCTURE AND POWER SOURCES OF GALACTIC WINDS IN MAJOR MERGERS (2013, background): “The highest outflow velocities from these starbursts apparently require very compact star formation (Overzier et al. 2009; Heckman et al. 2011; Diamond-Stanic et al. 2012).”
EVIDENCE FOR UBIQUITOUS COLLIMATED GALACTIC-SCALE OUTFLOWS ALONG THE STAR-FORMING SEQUENCE AT z ∼ 0.5 (2013, result): “This is fully consistent with most previous work on outflows in galaxies with similar SFRs (e.g., Rupke et al. 2005b; Grimes et al. 2009; Chen et al. 2010; Heckman et al. 2011; Martin et al. 2012), with two notable exceptions (discussed below).”
THE ORIGIN AND OPTICAL DEPTH OF IONIZING RADIATION IN THE “GREEN PEA” GALAXIES (2013, methodology): “Although the C ii line in the Pea is optically thin, Heckman et al. (2011) point out that the consistency between the galaxy’s Hα, UV, and IR luminosities makes the optically thin hypothesis tenuous.”