By stacking publicly available deep Spitzer/MIPS 24 \mu m and Herschel/PACS images for 213 z \simeq 2.18 { Ly } \alpha Emitters ( LAEs ) in GOODS-South , we obtain a strong upper limit to the IR luminosity of typical LAEs and discuss their attenuation curve for the first time .
The 3 \sigma upper limit L _ { TIR } ^ { 3 \sigma } = 1.1 \times 10 ^ { 10 } L _ { \odot } , determined from the MIPS data providing the lowest limit , gives IRX \equiv L _ { TIR } / L _ { UV } \leq 2.2 .
Here we assume that the local calibration between the 8 \mu m emission and the dust SED shape and metallicity applies at high redshifts and that our LAEs have low metallicities as suggested by previous studies .
The inferred escape fractions of { Ly } \alpha , 16 – 37 \% , and UV continuum , \geq 44 \% , are higher than the cosmic averages at the same epoch .
The SMC attenuation curve is consistent with the IRX and the UV slope \beta = -1.4 ^ { +0.2 } _ { -0.2 } of our stacked LAE , while the Meurer ’ s relation ( Calzetti curve ) predicts a 3.8 times higher IRX ; we also discuss the validity of PACS-based L _ { TIR } ^ { 3 \sigma } allowing the Meurer ’ s relation .
SED fitting using the Calzetti curve also gives a \sim 10 times higher SFR than from the L _ { TIR } ^ { 3 \sigma } and L _ { UV } .
With M _ { \star } = 6.3 ^ { +0.8 } _ { -2.0 } \times 10 ^ { 8 } \mathrm { M _ { \odot } } , our LAEs lie on a lower-mass extrapolation of the star formation main sequence at z \sim 2 , suggesting that the majority of z \sim 2 LAEs are mildly star forming with relatively old ages of \sim 200 Myr .
The faint L _ { TIR } ^ { 3 \sigma } implies that LAEs contribute little to the faint ( \gtrsim 100 ~ { } \mu Jy ) submm number counts by ALMA .