Detection of high Lyman continuum leakage from four low-redshift compact star-forming galaxies

By Y. Izotov, Daniel Schaerer, T. Thuan, G. Worseck, N. Guseva, I. Orlitová, A. Observatory, Ukrainian National Academy of Sciences, Kyiv, Ukraine and 17 more. 2016

257 citations recorded by the source corpus.

Following our first detection reported in Izotov et al. (2016), we present the detection of Lyman continuum (LyC) radiation of four other compact star-forming galaxies observed with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST). These galaxies, at redshifts of z~0.3, are characterized by high emission-line flux ratios [OIII]5007/[OII]3727 > 5. The escape fractions of the LyC radiation fesc(LyC) in these galaxies are in the range of ~6%-13%, the highest values found so far in low-redshift star-forming galaxies. Narrow double-peaked Lyalpha emission lines are detected in the spectra of all four galaxies, compatible with predictions for Lyman continuum leakers. We find escape fractions of Lyalpha, fesc(Lyalpha) ~20%-40%, among the highest known for Lyalpha emitters (LAEs). Surface brightness profiles produced from the COS acquisition images reveal bright star-forming regions in the center and exponential discs in the outskirts with disc scale lengths alpha in the range ~0.6-1.4 kpc. Our galaxies are characterized by low metallicity, ~1/8-1/5 solar, low stellar mass ~(0.2 - 4)e9 Msun, high star formation rates SFR~14-36 Msun/yr, and high SFR densities Sigma~2-35 Msun/yr/kpc^2. These properties are comparable to those of high-redshift star-forming galaxies. Finally, our observations, combined with our first detection reported in Izotov et al. (2016), reveal that a selection for compact star-forming galaxies showing high [OIII]5007/[OII]3727 ratios appears to pick up very efficiently sources with escaping Lyman continuum radiation: all five of our selected galaxies are LyC leakers.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/210c7c1ed424fc80cf2959caa7aaa325313ed6b8

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. R. Dav'e
2. P. Hopkins
3. C. Conroy
4. Naveen A. Reddy
5. C. Steidel
6. A. Shapley
7. L. Hernquist
8. R. Somerville

In Nuclear and High Energy Physics

1. Naveen A. Reddy
2. C. Steidel
3. A. Shapley
4. M. Pettini
5. P. Behroozi
6. C. Conroy
7. Daniel Schaerer
8. S. Tacchella

Citations in the corpus

• The COS-Halos Survey: Metallicities in the Low-redshift Circumgalactic Medium (2017, background): “Most measurements have indicated a nearly negligible value (e.g. Leitherer et al. 1995), but recent work has identified at least a subset of systems with significant leakage (Borthakur et al. 2014; Izotov et al. 2016; Leitherer et al. 2016).”
• Rapid Reionization by the Oligarchs: The Case for Massive, UV-bright, Star-forming Galaxies with High Escape Fractions (2019, background): “The campaigns targeting Green Peas at z∼0.3 with Hubble Space Telescope (HST)/COS have proven remarkably efficient (boasting a 100% success rate for LyC detection; Izotov et al. 2016b, 2018b).”
• Lyman-α spectral properties of five newly discovered Lyman continuum emitters (2016, methodology): “The Lyα escape fractions, reported in Table 1, were calculated from the Balmer lines in the SDSS spectra for our five LCEs by Izotov et al. (2016b) and J0921+04509, by the equation: f Lyαesc = F(Lyα)/(8.2 × F(Hα)corr), (2) where F(Lyα) is the observed Lyα flux, and F(Hα)corr the Hα flux corrected…”
• J1154+2443: a low-redshift compact star-forming galaxy with a 46 per cent leakage of Lyman continuum photons (2017, methodology): “Then, adopting R(V), the extinction A(V) in the V band is derived from the relation C(Hβ)/A(V) = f [R(V)] (Izotov et al. 2016a).”
• Low-redshift Lyman continuum leaking galaxies with high [O iii]/[O ii] ratios (2018, methodology): “A quick comparison with the properties of the z ∼ 0.3 galaxies studied in our work (Izotov et al. 2016a, 2018, and the present work) shows that our sources have significantly stronger emission lines (EW([O iii]λ5007) ∼ 1400 − 2100 Å compared to ∼ 400 Å rest-frame) and higher O32 line ratios…”
• Conditions for Reionizing the Universe with a Low Galaxy Ionizing Photon Escape Fraction (2019, background): “…an increasing success rate of robust direct detections of Lyman continuum radiation with fesc10%, both at z∼2–4 (e.g., Steidel et al. 2001; de Barros & Vanzella 2016; Shapley et al. 2016; Bian et al. 2017; Fletcher et al. 2018; Vanzella et al. 2018), and locally (Izotov et al. 2016a, 2016b, 2018).”
• The Keck Lyman Continuum Spectroscopic Survey (KLCS): The Emergent Ionizing Spectrum of Galaxies at z ∼ 3 (2018, background): “…Space Telescope (HST) of low-redshift galaxies that have been identified as likely analogs of the high redshift objects (e.g., Borthakur et al. 2014; Izotov et al. 2016a,b; Leitherer et al. 2016), such as ‘Lyman break analogs” (LBAs; Overzier et al. 2009), and “Green Peas” (Cardamone et al. 2009.)”
• Modeling the Radio Background from the First Black Holes at Cosmic Dawn: Implications for the 21 cm Absorption Amplitude (2018, background): “Ma et al. (2015) found escape fractions between 0.01 and 0.05 for ∼109Me halos in simulations, while observations of larger galaxies at lower redshifts found escape fractions fesc∼10 −2 –0.5 (Bridge et al. 2010; Izotov et al. 2016; Vanzella et al. 2016; Vasei et al. 2016; Grazian et al. 2017).”