Primordial star clusters at extreme magnification
  Gravitationally lensed galaxies with magnification ~10-100 are routinely
detected at high redshifts, but magnifications significantly higher than this
are hampered by a combination of low probability and large source sizes.
Magnifications of ~1000 may nonetheless be relevant in the case of
intrinsically small, high-redshift objects with very high number densities.
Here, we explore the prospects of detecting compact (< 10 pc), high-redshift (z
> 7) Population III star clusters at such extreme magnifications in large-area
surveys with planned telescopes like Euclid, WFIRST and WISH. We find that the
planned WISH 100 sq. deg ultradeep survey may be able to detect a small number
of such objects, provided that the total stellar mass of these star clusters is
> 10000 solar masses. If candidates for such lensed Population III star
clusters are found, follow-up spectroscopy of the surrounding nebula with the
James Webb Space Telescope or groundbased Extremely Large Telescopes should be
able to confirm the Population III nature of these objects. Multiband
photometry of these objects with the James Webb Space Telescope also has the
potential to confirm that the stellar initial mass function in these Population
III star clusters is top-heavy, as supported by current simulations.
