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We present results on two related topics: 1. A discussion of high redshift candidates (z>4.5), and 2. A study of very small galaxies at intermediate redshifts, both sets being detected in the region of the northern Hubble Deep Field covered by deep NICMOS observations at 1.6 and 1.1 microns. The high redshift candidates are just those with redshift z>4.5 as given in the recent catalog of Thompson, Weymann and Storrie-Lombardi, while the ``small galaxy sample is defined to be those objects with isophotal area <= 0.2 squ. arcsec and with photometric redshifts 1<z<4.5. Of the 19 possible high redshift candidates listed in the Thompson et al. catalog, 11 have (nominal) photometric redshifts less than 5.0. Of these, however, only 4 are ``robust in the sense of yielding high redshifts when the fluxes are randomly perturbed with errors comparable to the estimated measuring error in each wave band. For the 8 other objects with nominal photometric redshifts greater than 5.0, one (WFPC2 4--473) has a published spectroscopic redshift. Of the remaining 7, 4 are robust in the sense indicated above. Two of these form a close pair (NIC 586 and NIC 107). The redshift of the object having formally the highest redshift, at 6.56 (NIC118 = WFPC2 4--601), is problematic, since F606W and F814W flux are clearly present, and the nature of this object poses a dilemma. (abridged)
We study the molecular gas properties of high-$z$ galaxies observed in the ALMA Spectroscopic Survey (ASPECS) that targets a $sim1$ arcmin$^2$ region in the Hubble Ultra Deep Field (UDF), a blind survey of CO emission (tracing molecular gas) in the 3
We have searched for star-forming galaxies at z~7 by applying the Lyman-break technique to newly-released 1.1micron Y-band images from WFC3 on HST. By comparing these images of the Hubble Ultra Deep Field with the ACS z-band (0.85micron), we identify
We have conducted a two-layered spectroscopic survey (1x1 ultra deep and 3x3 deep regions) in the Hubble Ultra Deep Field (HUDF) with the Multi Unit Spectroscopic Explorer (MUSE). The combination of a large field of view, high sensitivity, and wide w
Tadpole galaxies have a head-tail shape with a large clump of star formation at the head and a diffuse tail or streak of stars off to one side. We measured the head and tail masses, ages, surface brightnesses, and sizes for 66 tadpoles in the Hubble
We analyse the spatially resolved colours of distant galaxies of known redshift in the Hubble Deep Field, using a new technique based on matching resolved four-band internal colour data to the predictions of evolutionary synthesis models. We quantify