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tokens: z LAEs with high-resolution HST narrow-band imaging (Bond et al. 2010 ; Finkelstein et al. 2011 ). Bond et al. ( 2010 ) suggested that Ly α sizes are compact and similar to UV emission, but Finkelstein et al. ( 2011 ) posited that the half light radius of Ly α appears ∼1.6 times larger than the half light radius of UV continuum. These narrow-band HST images of high- z LAEs are very hard to obtain and have low S/Ns. Thus, the Ly α and UV sizes of low- z LAEs are valuable. Because Green Peas are analogs of high- z LAEs, our results suggest that most high- z LAEs likely have larger Ly α than UV sizes. The extended Ly α emission probably indicates gas outflows around galaxies illuminated by Ly α light. One interesting question regards the redshift evolution of Ly α sizes of LAEs. Recently, Wisotzki et al. ( 2016 ) measured Ly α radial profiles of a sample of LAEs at z = 3–6 from VLT/MUSE data. They found that, in 12 LAEs with both Ly α and UV continuum sizes, the Ly α light is considerably more extended than the UV continuum light. Here, we compare the sizes of Green Peas and the MUSE LAEs. Using the Ly α radial profiles in Wisotzki et al. ( 2016 ), we measured the deconvolved Ly α scale radius r e , assuming intrinsic exponential profiles, so that the methods are same when measuring the r e of MUSE LAES and Green Peas. As shown in Figure 5 , the Ly α -to-UV size ratios of Green Peas and MUSE LAEs are very similar. Notice that some MUSE LAEs have extended Ly α halos far beyond the scale radius. For Green Peas, however, we do not have robust data to characterize the Ly α emission beyond a few Kpcs. Figure 5. Left: Comparison of the Ly α- to-UV scale length of Green Peas (green squares) and MUSE z = 3–6 LAEs sample (red dots) (Wisotzki et al. 2016 ). The Ly α scale lengths of MUSE LAEs are measured from the radial profile in Wisotzki et al. ( 2016 ) using the same method as Green Peas. Right: Comparison of the Ly α -to-UV Petrosian 20% (P20) radius of LARS ∼ 0 galaxies and MUSE LAEs. Notice that the Petrosian 20% radius of MUSE sample is measured from the best-fit model of radial profile. The dashed cyan lines show constant ratios of 1:1, 2:1, 5:1, and 10:1. In the right panel of Figure 5 , we compare the Petrosian 20% radius ( R P20 ) of MUSE LAEs (Table 2 in Wisotzki et al. ( 2016 )) to that of the LARS sample (Table 1 in Hayes et al. 2014 ). Compared to the five strong Ly α emitters in LARS sample (marked by stars, LARS01, 02, 05, 07, and 14), the MUSE LAEs only have about two times larger ratios of R P20 (Ly α ) to R P20 (UV). One caveat of the comparison is that the Petrosian radius of MUSE sample is measured from the best-fit model of radial profile, instead of the observed data, which is different from the method used in the LARS sample. This might be the reason that the R P20 (UV) of MUSE LAEs are about 2–4 kpc, approximately a factor of three larger than the R P20 (UV) of the five LARS Ly α emitters. Based on our rough comparison of Green