What Powers Lyman alpha Blobs?
  Lyman alpha blobs (LABs) are spatially extended lyman alpha nebulae seen at
high redshift. The origin of Lyman alpha emission in the LABs is still unclear
and under debate. To study their heating mechanism(s), we present Australia
Telescope Compact Array (ATCA) observations of the 20 cm radio emission and
Herschel PACS and SPIRE measurements of the far-infrared (FIR) emission towards
the four LABs in the protocluster J2143-4423 at z=2.38. Among the four LABs, B6
and B7 are detected in the radio with fluxes of 67+/-17 microJy and 77+/-16
microJy, respectively, and B5 is marginally detected at 3 sigma (51+/-16
microJy). For all detected sources, their radio positions are consistent with
the central positions of the LABs. B6 and B7 are obviously also detected in the
FIR. By fitting the data with different templates, we obtained redshifts of
2.20$^{+0.30}_{-0.35}$ for B6 and 2.20$^{+0.45}_{-0.30}$ for B7 which are
consistent with the redshift of the lyman alpha emission within uncertainties,
indicating that both FIR sources are likely associated with the LABs. The
associated FIR emission in B6 and B7 and high star formation rates strongly
favor star formation in galaxies as an important powering source for the lyman
alpha emission in both LABs. However, the other two, B1 and B5, are
predominantly driven by the active galactic nuclei or other sources of energy
still to be specified, but not mainly by star formation. In general, the LABs
are powered by quite diverse sources of energy.
