1. Complex Lya Profiles in z=6.6 Ultraluminous Lya Emitters
Amy Barger
E. Hu, A. Songaila, L. Cowie, G. Hasinger, B. Rosenwasser, C. Waters

2. Multi-Component Lya Profiles at Low z
At low z, where LAEs are not expected to be strongly affected by IGM opacity, a variety of profiles are observed (see also Kulas+12):
multi-component profiles
red tails and sharp blue-side cutoffs (so this type of profile can arise even without IGM scattering)
Yamada+12
Scarlata+18
These features are a consequence of Lya scattering in the galaxy itself
At low z, ~30-50% of LAEs are found to have a blue wing

3. Multi-Component Profiles at High z?
In contrast, at z~6.6, the blue wing is expected to be removed by scattering from intergalactic HI
Indeed, this is observed for nearly all z~6.6 LAEs with Lya luminosities < erg/s
However, the most luminous LAEs may be able to ionize a sufficiently large HII region around them to enable the full Lya profile of the galaxy to get out
If so, and if the underlying galaxy properties are similar at high z to those at low z, then one might find multi-component profiles to be a common feature
14” FWHM positions accurate to about 4” or better
Hubble Deep Field-Proper

4. Science Goal
Our goal is to develop a substantial sample (several 10s) of ultraluminous LAEs with Lya luminosities > erg/s and see whether any of them show complex profiles
Ultimately, we would like to find whether there is a characteristic Lya luminosity above which one sees the intrinsic galaxy profile
14” FWHM positions accurate to about 4” or better
Hubble Deep Field-Proper

5. HEROES Survey of the North Ecliptic Pole (NEP)
to search for ultraluminous LAEs
Close-packed stepping pattern of 1 deg offsets and the N-Shot mosaic pattern with NDITH = 5
Blue circle: area of current observations
Red circle: area of full HEROES survey
A planned 120 deg2 area NB921 survey using the 1.5 deg diameter Hyper Suprime-Cam (HSC), with 55 deg2 so far (most uniform area is 30 deg2)
The 1s noise in a 2’’ diameter aperture ranges from 25.4 to 26.1
Also includes g’, r’, i’, z’, y’, and NB816 images from HSC, and U and J from MegaPrime/MegaCam and WIRCam on CFHT
In z’, the 1s noise in a 2’’ diameter aperture ranges from 26.2 to 27.0
There are other examples of ultraluminous LAEs in, e.g., Ouchi+09, Matthee+15, Konno+18, Sobral+18, but our sample has uniform Keck/DEIMOS spectroscopic followup

6. LAE Candidate Selection
5 - 9s selection criterion throughout the area
Candidate LAEs at z=6.6, if also not detected above 2s in any of the g’, r’, and i’ bands
2.8 million sources on figure!

7. Spectroscopic Follow-up with Keck/DEIMOS
of ultraluminous LAE candidates (prioritize z’ detections)
NEP
COSMOS
5 spectroscopically confirmed LAEs (red)
1 high-z AGN (gold) 1 [OIII] emitter (blue)
3 spectroscopically confirmed LAEs (red)
(2 were previously confirmed by Sobral+15)
Rectangle: uniform 30 deg2 area used here
Shaded area: 3 deg2 field of Hu+16
Rectangle: smaller area of Sobral+15

8. AGN Contamination
NB surveys pick up AGN, so this is a source of contamination in photometric samples
1/7 of our NEP ultraluminous LAE candidates is a broad-line AGN
NEP chosen to match deepest areas of eROSITA to look for high-z AGN (Merloni et al. 2012)
Note: the other LAEs do not show NV in the optical and also do not show CIV in the NIR (or HeII)

9. COSMOS Ultraluminous LAEs
Blue wing
Broader
Secondary red component
Lya profiles (black) are compared with the composite profile of 31 lower luminosity LAEs from Hu+10 (red; normalized to the peak flux in each spectrum)

10. NEP Ultraluminous LAEs

11. (these will contaminate a photometrically selected sample)
Concern: small doublet separation in [OII] may produce spectra that look like complex Lya profiles
However, [OII] emitters are generally fairly easily seen in the g-band, while LAEs, including COLA1 and NEPLA4, are much fainter (i.e., undetected)
NB921,
z’, r’
g’,r,i’
Only [OIII] emitters contain any sources that satisfy our LAE selection z’ – NB > 1.3
(these will contaminate a photometrically selected sample)

12. Moreover, for NEPLA4, the velocity separation between the blue wing and the peak is larger than the [OII] doublet separation
It also has a strong red tail

13. Summary
The most ultraluminous LAEs (Lya luminosities > erg/s) at z~6.6 also seem to show a range of profiles, including ones with complex profiles
Numbers are small currently, but the complex profile fraction seems similar to that at low z (~30%)
Thus, we may be able to determine the characteristic Lya luminosity where the bubbles are both large enough and ionized enough for us to see the intrinsic galaxy profile
This could perhaps let us estimate the ionizing escape from the LAE galaxy
14” FWHM positions accurate to about 4” or better
Hubble Deep Field-Proper