The traditional view that Ly \alpha emission and dust should be mutually exclusive has been questioned more and more often ; most notably , the observations of Ly \alpha emission from ULIRGs seem to counter this view .
In this paper we seek to address the reverse question .
How large a fraction of Ly \alpha selected galaxies are ULIRGs ?
Using two samples of 24/25 Ly \alpha emitting galaxies at z = 0.3 / 2.3 , we perform this test , including results at z = 3.1 , and find that , whereas the ULIRG fraction at z = 3.1 is very small , it systematically increases towards lower redshifts .
There is a hint that this evolution may be quite sudden and that it happens around a redshift of z \sim 2.5 .
After measuring the infrared luminosities of the Ly \alpha emitters , we find that they are in the normal to ULIRG range in the lower redshift sample , while the higher redshift galaxies all have luminosities in the ULIRG category .
The Ly \alpha escape fractions for these infrared bright galaxies are in the range 1 - 100 % in the z = 0.3 galaxies , but are very low in the z = 2.3 galaxies , 0.4 % on average .
The unobscured star formation rates are very high , ranging from 500 to more than 5000 M _ { \odot } yr ^ { -1 } , and the dust attenuation derived are in the range 0.0 < A _ { V } < 3.5 .