Statistical properties of di ff use Ly haloes around star-forming - PowerPoint PPT Presentation

Statistical properties of di ff use Ly α haloes around star-forming galaxies at z ~ 2 Momose+16, MNRAS, 457, 2318 Rieko Momose （ NTHU → U. Tokyo from next week ） Ouchi, M., Nakajima, K., Ono, Y., Shibuya, T., Shimasaku, K., Suraphong, Y., Mori, M., Umemura, M.

m UV (ABmag) LAHs’ scale-length LAE surface density （kpc） INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY New questions for the LAHs’ study Cont. Ly α What is the origin of LAHs? Which physical parameters of LAEs determine LAHs’ size? param. Y N Zheng+11, Feldmeier+13, Steidel+11, L UV Matsuda+12 Xue+17, Leclercq+17 L Ly α Xue+17, Zheng+11 Leclercq+17 M DH Zheng+11 r s_cont Leclercq+17 Steidel+11; Matsuda+12; MR+14; Wisotzki+16 2

INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY Methodology of this study Data ~ 3,500 LAEs at z = 2.2 stack Method Make 5 subsamples as a function of LAEs’ - Ly α luminosity - M UV - EW 0 (Ly α ) - UV-slope β investigate the relation LAH’s size Physical parameters (ex Ly α luminosity) 3

log log log log log log log log log log INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY Cumulative radial profile of L Ly α Radius [kpc] Radius [kpc] Trend from all subsamples 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 5 5 EW 0 L Ly α L Ly α increases in LAHs Ly α luminosity normalized in 2” aperture 4 4 L Ly α (r) / L Ly α (r=1 arcsec) L Ly α (r) / L Ly α (r=1 arcsec) 3 3 L Ly α , EW 0 More extend in faint L Ly α 2 2 log(L Ly α ) = 42.6 EW 0 = 22 and small EW 0 subsamples log(L Ly α ) = 42.3 EW 0 = 30 log(L Ly α ) = 42.6 EW 0 = 22 1 1 log(L Ly α ) = 42.1 log(L Ly α ) = 42.3 EW 0 = 40 EW 0 = 30 log(L Ly α ) = 42.1 log(L Ly α ) = 41.9 EW 0 = 40 EW 0 = 63 log(L Ly α ) = 41.9 EW 0 = 63 log(L Ly α ) = 41.7 EW 0 = 150 log(L Ly α ) = 41.7 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 EW 0 = 150 5 0 0 5 M UV 0 2 4 6 8 10 0 2 4 6 8 10 M UV β Radius [arcsec] Radius [arcsec] More extend in bright M UV 4 4 L Ly α (r) / L Ly α (r=1 arcsec) (if exclude two subsamples with 3 3 large error-bars) 2 2 β = 0.68 M UV = − 21.1 β = − 0.54 β M UV = − 20.5 β = 0.68 M UV = − 21.1 1 1 β = − 1.4 β = − 0.54 M UV = − 20.1 M UV = − 20.5 β = − 1.4 M UV = − 20.1 M UV = − 19.7 β = − 2.0 β = − 2.0 M UV = − 19.7 No clear trend M UV = − 18.9 β = − 2.6 β = − 2.6 M UV = − 18.9 0 0 0 2 4 6 8 10 0 2 4 6 8 10 Radius [arcsec] Radius [arcsec] 4

Strong Corr. p = -0.7 (93%) Corr. No clear Corr. Corr. p = 0.7 (81%) p = -0.2 (45%) p = -0.9 (96%) INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY LAHs’ size 20 20 L Ly α EW 0 Best-fit Best Fit This Study This Study Matsuda et al. 2012 Momose et al. 2014 r n (Ly α ) [kpc] r n (Ly α ) [kpc] 15 15 10 10 5 5 41.0 41.5 42.0 42.5 43.0 0 20 40 60 80 100 120 140 160 EW 0 (Ly α ) [ Å ] log L (Ly α ) [erg s -1 ] in a 1 arcsec radius in a 1 arcsec radius 20 20 M UV β Best-fit Best Fit This Study This Study Matsuda et al. 2012 r n (Ly α ) [kpc] r n (Ly α ) [kpc] 15 15 10 10 5 5 − 25 − 24 − 23 − 22 − 21 − 20 − 19 − 18 − 3 − 2 − 1 0 1 M UV [mag] UV slope β in a 1 arcsec radius in a 1 arcsec radius 5

・ INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY Origin of LAHs (a) Scattered light (b) Cold streams (c) Satellite galaxies in the CGM LAE LAE LAE ・ Stars Ly α emission 6

e.g. Neufeld 91, Verhamme+06, Dijkstra+12 INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY (a) Scattered light in the CGM Origin of Ly α photons Stellar Component Observed - Produced in SF regions and/ of a galaxy or AGNs HI in CGM - Ly α escape mechanisms - outflow - clumpy clouds Ly α emission - low column density Observational evidences - Spectroscopic observations have shown the evidence - outflow - low column density - We cannot examine spectra or gas distribution from our data We cannot rule out this scenario. 7

M DH ~10 11 M DH ~10 12 M DH ~10 13 Rosdahl & Blaizot 12 INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY (b) Cold streams Origin of Ly α photons - Dense and clod gas (10 4 K) can emit in Ly α - Produce an extended Ly α nebula around a galaxy - size of the nebula depends on the dark halo mass M DH - widely extend with 
 M DH > 10 12 M ◉ - extend r ~ 20 kpc with 
 M DH ~ 10 11 M ◉ Comparison with our results 1 - M UV correlates with M DH - Large LAHs are found in UV luminous LAEs => consistent 8

Rosdahl & Blaizot 12 INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY (b) Cold streams Origin of Ly α photons - Dense and clod gas (10 4 K) can emit in Ly α - Produce an extended Ly α nebula around a galaxy - size of the nebula depends on the dark halo mass M DH 0 10 20 30 40 50 60 70 80 - widely extend with 
 5 Ly α luminosity normalized in 2” aperture M DH > 10 12 M ◉ 4 L Ly α (r) / L Ly α (r=1 arcsec) - extend r ~ 20 kpc with 
 M DH ~ 10 11 M ◉ 3 Comparison with our results 1 2 - M UV correlates with M DH M UV = − 21.1 - Large LAHs are found in UV 1 M UV = − 20.5 M UV = − 20.1 luminous LAEs => consistent M UV = − 19.7 M UV = − 18.9 0 0 2 4 6 8 10 8 Radius [arcsec]

INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY (b) Cold streams Comparison with our results 2 Radius [kpc] 0 10 20 30 40 50 60 70 80 - EW 0 of our M UV subsamples are 
 3 lower than 77 Å => inconsistent - maximum value for EW 0 originating from popII star formation is 240 Å log EW 0 (Ly α ) [ Å ] 2 - if cold streams contributes LAHs, EW 0 at large radii should be larger than 240 Å 1 M UV = − 21.1 M UV = − 20.5 Our LAHs are not produced M UV = − 20.1 0 0 2 4 6 8 10 by cold streams. Radius [arcsec] 9

galaxy satellite UV Lyα Lake+15 INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY (c) Satellite galaxies Origin of Ly α photons - Star forming regions in satellite galaxies around LAEs - If total radiation from satellite galaxies is strong, they would produce extended Ly α emission Comparison with our results - If there are satellite galaxies, 
 extended UV emission should 
 also exist in our stacked UV images - Our stacked UV images 
 su ff er from sky-over subtraction - It may cancel out the evidence 
 of satellite galaxies

galaxy satellite UV Lyα Lake+15 INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY (c) Satellite galaxies Origin of Ly α photons - Star forming regions in satellite galaxies around LAEs - If total radiation from satellite galaxies is strong, they would produce extended Ly α emission Comparison with our results - If there are satellite galaxies, 
 extended UV emission should 
 also exist in our stacked UV images - Our stacked UV images 
 su ff er from sky-over subtraction - It may cancel out the evidence 
 of satellite galaxies We cannot rule out this scenario

INTRODUCTION METHODOLOGY RESULTS DISCUSSION SUMMARY Summary Physical parameters of LAEs to determine LAHs’ size LAHs’ sizes tend to be large with - fainter in L Ly α - smaller in EW 0 - brighter in M UV Origin of LAHs (a) Scattered light in the CGM ==> we cannot rule out (b) Cold streams ==> not the major contributor of our LAHs (c) Satellite galaxies ==> we cannot rule out → Haruka will discuss more details in her talk! 11

35 Matsuda+ 2012 Steidel+ 2011 30 This Study 25 r n (Ly α ) [kpc] 20 15 10 5 0 5 − 1 0 1 2 3 4 6 δ LAE