Ly Emission in Low Metallicity Galaxies at z ~2 Dawn Erb - PowerPoint PPT Presentation

Ly 𝛃 Emission in Low Metallicity Galaxies at z ~2 Dawn Erb University of Wisconsin-Milwaukee Tokyo Spring Cosmic Ly 𝛃 Workshop March 27, 2018

Collaborators Danielle Berg University of Wisconsin-Milwaukee Ohio State University Naveen Reddy (UC Riverside) Chuck Steidel (Caltech) Alice Shapley (UCLA) Max Pettini (Cambridge) Gabriel Brammer (STSci) Allison Strom (Carnegie) David Kaplan (UW-Milwaukee) Ryan Trainor (Franklin & Marshall)

Ly 𝛃 emission stronger at low metallicity 0 . 030 Extreme KBSS 0 . 025 1 . 0 Green Peas 0 . 020 Relative number 0 . 015 0 . 5 0 . 010 Log ([O III]/H β ) 0 . 005 0 . 000 − 60 − 40 − 20 0 20 40 60 80 100 120 140 160 180 0 . 0 Ly α equivalent width (˚ A) 1 . 0 0 . 9 − 0 . 5 0 . 8 Extreme KBSS − 1 . 0 0 . 7 Green Peas − 1 . 8 − 1 . 6 − 1 . 4 − 1 . 2 − 1 . 0 − 2 . 0 − 1 . 5 − 1 . 0 − 0 . 5 0 . 0 0 . 5 Log ([N II]/H α ) Erb et al 2016 see also Trainor et al 2016

Relationships between strength and line profile Ly 𝛃 equivalent width anti-correlated with velocity o ff set Double peaks unresolved at low resolution Erb et al 2014

Diversity among Ly 𝛃 -emitters 3 arcsec HST WFC3 F160W Law et al 2012 Q2343-BX418 Q2343-BX660 M ★ = 5 x 10 9 M ⦿ M ★ = 2 x 10 9 M ⦿ SFR = 50 M ⦿ yr -1 SFR = 23 M ⦿ yr -1 SSFR = 18 Gyr -1 SSFR = 4 Gyr -1 12 + log(O/H) = 8.08 (T e ) 12 + log(O/H) = 8.13 (T e ) O32 = 9.66 O32 = 10.98 O/H, O32 from Steidel et al 2014

Ly 𝛃 profile variations BX418 with VLT XSHOOTER 5 R=6200 Archival data, Terlevich et al 2015 4 18 LRIS 3 600-line grism Flux 16 2 14 1 12 0 Normalized Flux − 2000 − 1500 − 1000 − 500 0 500 1000 1500 2000 10 Velocity (km s − 1 ) 8 6 BX418 4 BX660 2 0 − 3000 − 2000 − 1000 0 1000 2000 3000 Velocity (km s − 1 ) Erb et al 2018a, in prep

Absorption lines trace variations in outflows 1 . 4 BX418 BX660 1 . 2 1 . 0 Normalized Flux 0 . 8 0 . 6 0 . 4 Si IV λ 1394 Si IV λ 1403 0 . 2 0 . 0 − 2000 − 1000 0 1000 2000 3000 Velocity (km s − 1 ) Erb et al 2018a, in prep

Absorption lines trace variations in outflows 1 . 4 1 . 4 1 . 2 1 . 2 Normalized Flux BX418 1 . 0 1 . 0 BX660 0 . 8 0 . 8 0 . 6 0 . 6 Si II λ 1304 0 . 4 0 . 4 Si II λ 1260 O I λ 1302 0 . 2 0 . 2 0 . 0 0 . 0 − 1500 − 1000 − 500 0 500 1000 1500 − 1500 − 1000 − 500 0 500 1000 1500 Velocity (km s − 1 ) Velocity (km s − 1 ) 1 . 4 1 . 4 1 . 2 1 . 2 1 . 0 1 . 0 0 . 8 0 . 8 0 . 6 0 . 6 0 . 4 0 . 4 C II λ 1334 Si II λ 1527 0 . 2 0 . 2 0 . 0 0 . 0 − 1500 − 1000 − 500 0 500 1000 1500 − 1500 − 1000 − 500 0 500 1000 1500 Velocity (km s − 1 ) Velocity (km s − 1 ) Erb et al 2018a, in prep

Analysis of larger sample underway 18 6 16 Q0142-BX165 Q0207-BX144 5 Flux density ( µ Jy) Flux density ( µ Jy) 14 W Ly α = 61 ˚ A W Ly α = 38 ˚ A 12 4 10 3 8 6 2 4 1 2 0 0 1200 1205 1210 1215 1220 1225 1230 1200 1205 1210 1215 1220 1225 1230 Rest Wavelength (˚ Rest Wavelength (˚ A) A) 5 10 Q0207-BX87 Q0207-BX74 Flux density ( µ Jy) Flux density ( µ Jy) 4 W Ly α = 78 ˚ A W Ly α = 102 ˚ A 8 3 6 2 4 C II λ 1334 1 2 0 0 1200 1205 1210 1215 1220 1225 1230 1200 1205 1210 1215 1220 1225 1230 Rest Wavelength (˚ Rest Wavelength (˚ A) A) Erb et al 2018a, in prep

Implications and next steps Otherwise similar low metallicity galaxies have varying CGM properties: relevant to LyC escape 1 Low metallicity and high ionization necessary but not su ffi cient Expanding the sample: what can we learn from the most extreme objects? 2 New results from KCWI: what can we learn from integral field spectroscopy?

Low metallicity and high ionization at z=1.85 1 Berg et al 2018, arxiv:1803.02340

Ly 𝛃 emission does not require outflows 1 . 6 Average Absorption Low Ionization 1 . 4 High Ionization Normalized Flux OIII] λ 1660 OIII] λ 1666 1 . 2 1 . 0 0 . 8 0 . 6 − 1000 − 500 0 500 1000 Velocity km s − 1 See also Jaskot et al 2017 Berg et al 2018, arxiv:1803.02340

Narrowband Ly 𝛃 imaging with HST Ly 𝛃 + continuum Continuum-subtracted Ly 𝛃 O ff -line continuum Spectroscopic slit losses ~30% Ly 𝛃 equivalent width 190 Å , escape fraction ~10% Di ff erential lensing magnification? Erb et al 2018b, in prep

Spatially extended Ly 𝛃 Erb et al 2018b, in prep

Q2343-BX418 with KCWI preliminary 2 30 kpc Erb et al 2018c, in prep

Q2343-BX418 with KCWI 30 kpc Erb et al 2018c, in prep

Mapping the Ly 𝛃 peak ratio Erb et al 2018c, in prep

Mapping the Ly 𝛃 peak ratio ∆ v peak = 600 km s − 1 Erb et al 2018c, in prep

Mapping the Ly 𝛃 peak ratio ∆ v peak = 450 km s − 1 Erb et al 2018c, in prep

Mapping the Ly 𝛃 peak separation Erb et al 2018c, in prep

What does it mean? Spatial variations in Ly 𝛃 profile depend on - column density and covering fraction of neutral hydrogen - variations in outflow velocity, including projection e ff ects Full modeling required

Summary Q2343-BX418 Ly 𝛃 emission stronger at low metallicity, Q2343-BX660 40 SL2S J0217 but CGM properties vary widely 30 Normalized Flux Important for LyC escape 20 Low metallicity and high ionization 10 necessary but not su ffi cient 0 − 3000 − 2000 − 1000 0 1000 2000 3000 Velocity (km s − 1 ) Next steps: Quantify diversity in low mass samples Expand dynamic range to most extreme objects Map the CGM with emission Ly 𝛃