New Constraints on the Lyman Continuum Escape Fraction at z ~ 1.3

By B. Siana, H. Teplitz, J. Colbert, H. Ferguson, Mark Dickinson, T. Brown, Christopher J. Conselice, D. D. de Mello, J. Gardner, M. Giavalisco and 1 more. 2007

153 citations recorded by the source corpus.

We examine deep far-UV (1600 Å) imaging of the HDF-N and the HUDF to search for leaking Lyman continuum radiation from starburst galaxies at z ~ 1.3. There are 21 (primarily sub-L*) galaxies with spectroscopic redshifts between 1.1 < z < 1.5, and none are detected in the far-UV. We fit stellar population templates to the galaxies' optical/near-infrared SEDs to determine the starburst age and level of dust attenuation for each individual galaxy, giving a more accurate estimate of the intrinsic Lyman continuum ratio, f1500/f700, and allowing a conversion from f700 to relative escape fraction (fesc,rel). We show that previous high-redshift studies may have underestimated the amplitude of the Lyman break, and thus the relative escape fraction, by a factor ~2. Once the starburst age and intergalactic H I absorption are accounted for, 18 galaxies in our sample have limits to the relative escape fraction, fesc,rel < 1.0 with some limits as low as fesc,rel < 0.10 and a stacked limit of fesc,rel < 0.08. This demonstrates, for the first time, that most sub-L* galaxies at this redshift do not have large escape fractions. When combined with a similar study of more luminous galaxies at the same redshift, we show that, if all star-forming galaxies at z ~ 1 have similar relative escape fractions, the value must be less than 0.14 (3 σ). We also show that less than 20% (3 σ) of star-forming galaxies at z ~ 1 have relative escape fractions near unity. These limits contrast with the large escape fractions found at z ~ 3 and suggest that the average escape fraction has decreased between z ~ 3 and z ~ 1.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/8b1d7b8657502913f642d936ae4975b966b2bbc7

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Citations in the corpus

The observed ionization rate of the intergalactic medium and the ionizing emissivity at z≥ 5: evidence for a photon-starved and extended epoch of reionization (2007, background): “…must also be made for the very uncertain escape fraction of ionizing photons from their respective galactic environments (Giallongo et al. 2002; Fernández-Soto, Lanzetta & Chen 2003; Inoue, Iwata & Deharveng 2006; Siana et al. 2007), which is likely to vary considerably (Shapley et al. 2006).”
Escape of Ionizing Radiation from High-Redshift Galaxies (2007, background): “Note also that Siana et al. (2007) in their recent study of the Lyman continuum escape fractions in galaxies atz ∼ 1 also find small values (fesc.”
Using Lyman-α to detect galaxies that leak Lyman continuum (2014, background): “…that have been studied in LyC at z ∼ 1 with the Galaxy Evolution Explorer (GALEX) and the Hubble Space Telescope (HST), the situation still does not change much, and still no individual LyC-leaking galaxies are reported (Malkan et al. 2003; Siana et al. 2007; Cowie et al. 2009; Siana et al. 2010).”
New insights into the stellar content and physical conditions of star-forming galaxies at z = 2-3 from spectral modelling (2008, background): “The best limits at z 1 imply an upper limit fesc < 0.15 (Siana et al. 2007), consistent with the detection of near 100 per cent escape fraction in two out of 14 Lyman-break galaxies at z ∼ 3 and negligible values in the other 12 by Shapley et al. (2006).”
A DEEP HUBBLE SPACE TELESCOPE SEARCH FOR ESCAPING LYMAN CONTINUUM FLUX AT z ∼ 1.3: EVIDENCE FOR AN EVOLVING IONIZING EMISSIVITY (2010, methodology): “In Siana et al. (2007) we fit to both the Bruzual & Charlot (2003) and Starburst99 models (Leitherer et al. 1999) and got very similar Lyman-break amplitudes and stellar population parameters.”
UVUDF: ULTRAVIOLET THROUGH NEAR-INFRARED CATALOG AND PHOTOMETRIC REDSHIFTS OF GALAXIES IN THE HUBBLE ULTRA DEEP FIELD (2015, background): “Lastly, the SBC far-UV data (Siana et al. 2007) are also not used here as they contain very few sources and thus would not significantly affect the results.”
IONIZING PHOTON ESCAPE FRACTIONS FROM HIGH-REDSHIFT DWARF GALAXIES (2008, background): “Siana et al. (2007) examined starburst galaxies at z ∼ 1.3 and found that less than 20% have relative escape fractions4 near unity and a global absolute escape fraction of <∼ 0.04.”
GeV gamma-ray attenuation and the high-redshift UV background (2009, background): “…explore here but which has been seen in some simulations (Razoumov & Sommer-Larsen 2007, 2006), and as already mentioned may be suggested by observations which have detected Lyman continuum radiation from dis- tant (z ∼ 3) galaxies (Shapley et al. 2006), but not closer sources (Siana et al. 2007).”
THE RELATION BETWEEN STAR FORMATION RATE AND STELLAR MASS FOR GALAXIES AT 3.5 ⩽ z ⩽ 6.5 IN CANDELS (2014, background): “The escape fraction has been measured to be low ie. fesc ≈ 0 at low redshift z ∼1 (see Malkan et al. 2003; Siana et al. 2007, 2010; Bridge et al. 2010).”
Evolution in the properties of Lyman-α emitters from redshifts z ~ 3 to z ~ 2 (2008, background): “Møller & Jakobsen (1990) inferred that approximately 10% of galaxies at redshiftz = 2.25 have transmissions in the UV higher than 60%, in agreement with recent observations atz ∼ 1.5 (Siana et al. 2007).”
Escape of Lyman continuum radiation from local galaxies - Detection of leakage from the young starburst Tol 1247-232 (2013, background): “In contrast, these results, combined with the stacked samples at z ∼ 1 where upper limits of 1−2% have been found (Bridge et al. 2010; Siana et al. 2010, 2007; Cowie et al. 2009) and the stacked spectrum of local galaxies in this work, seems to imply very little, or even no, evolution in fesc…”
Feedback-regulated star formation and escape of LyC photons from mini-haloes during reionization (2016, background): “Star-forming galaxies at z ∼ 1 with LyC detection also show low escape fractions of a few percent (Siana et al. 2007, 2010; Bridge et al. 2010; Rutkowski et al. 2016).”
ON THE STELLAR POPULATIONS AND EVOLUTION OF STAR-FORMING GALAXIES AT 6.3 < z ⩽ 8.6 (2009, background): “The escape fraction of ionizing photons has been measured at lower redshifts, with fesc< 0.1 atz= 0, fesc= 0.08 atz∼ 1 (Siana et al. 2007), Galaxy Evolution at 6.3< z≤ 8.6 23 and measurements offesc = 0.15–0.6 atz∼ 3 (Steidel et al. 2001; Shapley et al. 2006).”
COMPARISON OF Hα AND UV STAR FORMATION RATES IN THE LOCAL VOLUME: SYSTEMATIC DISCREPANCIES FOR DWARF GALAXIES (2009, background): “Moreover, observations which have attempted to directly detect escaping Lyman continuum photons have all found upper-limits .10% (e.g., Leitherer et al. 1995, Bergvall et al. 2005, Grimes et al. 2007, Siana et al. 2007).”
Fluctuating feedback-regulated escape fraction of ionizing radiation in low-mass, high-redshift galaxies (2017, result): “At intermediate redshifts, most efforts have given null results or relatively loose upper limits (e.g. Malkan et al. 2003; Siana et al. 2007, 2010; Cowie et al. 2009), but all report a low upper limit on fesc.”
EXTREME FEEDBACK AND THE EPOCH OF REIONIZATION: CLUES IN THE LOCAL UNIVERSE (2011, background): “…ApJ, 632, 751 Schwartz, C., Martin, C., Chandar, R., Leitherer, C., Heckman, T., & Oey, M.S. 2006, ApJ, 646, 858 Shapley, A., Steidel, C., Pettini, M., & Adelberger, K. 2003, ApJ, 588, 65 Shapley, A., Steidel, C., Pettini, M., Adelberger, K., & Erb, D. 2006, ApJ, 651, 688 Siana et al. 2007, ApJ.”