Constraining stellar properties of intervening damped Ly{\alpha} and
  MgII absorbing galaxies toward GRB 050730
  We performed multi-band deep imaging of the field around GRB 050730 to
identify the host galaxies of intervening absorbers, which consist of a damped
Ly{\alpha} absorption (DLA) system at zabs=3.564, a sub-DLA system at
zabs=3.022, and strong MgII absorption systems at zabs=1.773 and 2.253. Our
observations were performed after the gamma-ray burst afterglow had
disappeared. Thus, our imaging survey has a higher sensitivity to the host
galaxies of the intervening absorbers than the normal imaging surveys in the
direction of QSOs, for which the QSO glare tends to hide the foreground
galaxies. In this deep imaging survey, we could not detect any unambiguous
candidates for the host galaxies of the intervening absorbers. Using the 3sigma
upper limit of the flux in the optical to mid-infrared observing bands, which
corresponds to the UV to optical bands in the rest-frame of the intervening
absorbers, we constrained the star-formation rates and stellar masses of the
hosts. We estimated the star-formation rates for the intervening absorbers as <
2.5 Msun/yr for z>3 DLAs and < 1.0 Msun/yr for z~2 MgII systems. Their stellar
masses are estimated to be several times 10^9 Msun or smaller for all
intervening galaxies. These properties are comparable to dwarf galaxies, rather
than the massive star-forming galaxies commonly seen in the z>2 galaxy surveys
based on emission-line selection or color selection.
