HST Imaging of the Ionizing Radiation from a Star-forming Galaxy at z=3.794
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HST Imaging of the Ionizing Radiation from a Star-forming Galaxy at z=3.794. / Ji, Zhiyuan; Giavalisco, Mauro; Vanzella, Eros; Siana, Brian; Pentericci, Laura; Jaskot, Anne; Liu, Teng; Nonino, Mario; Ferguson, Henry C.; Castellano, Marco; Mannucci, Filippo; Schaerer, Daniel; Fynbo, Johan Peter Uldall; Papovich, Casey; Carnall, Adam C.; Amorin, Ricardo; Simons, Raymond C.; Hathi, Nimish; Cullen, Fergus; McLeod, Derek.
In: Astrophysical Journal, Vol. 888, No. 2, 109, 10.01.2020.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - HST Imaging of the Ionizing Radiation from a Star-forming Galaxy at z=3.794
AU - Ji, Zhiyuan
AU - Giavalisco, Mauro
AU - Vanzella, Eros
AU - Siana, Brian
AU - Pentericci, Laura
AU - Jaskot, Anne
AU - Liu, Teng
AU - Nonino, Mario
AU - Ferguson, Henry C.
AU - Castellano, Marco
AU - Mannucci, Filippo
AU - Schaerer, Daniel
AU - Fynbo, Johan Peter Uldall
AU - Papovich, Casey
AU - Carnall, Adam C.
AU - Amorin, Ricardo
AU - Simons, Raymond C.
AU - Hathi, Nimish
AU - Cullen, Fergus
AU - McLeod, Derek
PY - 2020/1/10
Y1 - 2020/1/10
N2 - We report on the Hubble Space Telescope (HST) detection of the Lyman-continuum (LyC) radiation emitted by a galaxy at redshift z = 3.794 dubbed Ion1. The LyC from Ion1 is detected at 820-890 A with HST WFC3/UVIS in the F410M band (m(410) = 27.60 0.36 m(AB), peak signal-to-noise ratio (S/N) = 4.17 in an r = 012 aperture) and 700-830 A with the Very Large Telescope (VLT)/VIMOS in the U band (m(U) = 27.84 0.19 m(AB), peak S/N = 6.7 with an r = 06 aperture). A 20 hr VLT/VIMOS spectrum shows low- and high-ionization interstellar metal absorption lines and the P Cygni profile of C iv and Ly alpha in absorption. The latter spectral feature differs from what observed in known LyC emitters, which show strong Ly alpha emission. An HST far-UV color map reveals that the LyC emission escapes from a region of the galaxy that is bluer than the rest. The F410M image shows that the centroid of the LyC emission is offset from the centroid of the nonionizing UV emission by 012 003, corresponding to 0.85 0.21 kpc, and that its morphology is likely moderately resolved. These morphological characteristics favor a scenario where the LyC photons produced by massive stars escape from low H i column density "cavities" in the interstellar medium. We also collect the VIMOS U-band images of 107 Lyman-break galaxies at 3.40 z(spec) <3.95, i.e., sampling the LyC, and stack them with inverse-variance weights. No LyC emission is detected in the stacked image, resulting in a 32.5 m(AB) flux limit (1 sigma) and an upper limit of absolute LyC escape fraction f(esc)(abs)
AB - We report on the Hubble Space Telescope (HST) detection of the Lyman-continuum (LyC) radiation emitted by a galaxy at redshift z = 3.794 dubbed Ion1. The LyC from Ion1 is detected at 820-890 A with HST WFC3/UVIS in the F410M band (m(410) = 27.60 0.36 m(AB), peak signal-to-noise ratio (S/N) = 4.17 in an r = 012 aperture) and 700-830 A with the Very Large Telescope (VLT)/VIMOS in the U band (m(U) = 27.84 0.19 m(AB), peak S/N = 6.7 with an r = 06 aperture). A 20 hr VLT/VIMOS spectrum shows low- and high-ionization interstellar metal absorption lines and the P Cygni profile of C iv and Ly alpha in absorption. The latter spectral feature differs from what observed in known LyC emitters, which show strong Ly alpha emission. An HST far-UV color map reveals that the LyC emission escapes from a region of the galaxy that is bluer than the rest. The F410M image shows that the centroid of the LyC emission is offset from the centroid of the nonionizing UV emission by 012 003, corresponding to 0.85 0.21 kpc, and that its morphology is likely moderately resolved. These morphological characteristics favor a scenario where the LyC photons produced by massive stars escape from low H i column density "cavities" in the interstellar medium. We also collect the VIMOS U-band images of 107 Lyman-break galaxies at 3.40 z(spec) <3.95, i.e., sampling the LyC, and stack them with inverse-variance weights. No LyC emission is detected in the stacked image, resulting in a 32.5 m(AB) flux limit (1 sigma) and an upper limit of absolute LyC escape fraction f(esc)(abs)
KW - Reionization
KW - High-redshift galaxies
KW - Extragalactic astronomy
KW - ORIGINS DEEP SURVEY
KW - LYMAN-CONTINUUM EMISSION
KW - SPACE-TELESCOPE SEARCH
KW - GOODS-SOUTH FIELD
KW - ESCAPE FRACTION
KW - VLT/FORS2 SPECTROSCOPY
KW - LY-ALPHA
KW - FAR-ULTRAVIOLET
KW - CENT LEAKAGE
KW - PHOTONS
U2 - 10.3847/1538-4357/ab5fdc
DO - 10.3847/1538-4357/ab5fdc
M3 - Journal article
VL - 888
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 109
ER -
ID: 247444616