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Clumpy galaxies do not look like local galaxies even when the local galaxies are modified to appear as they would at high redshift. FUV images of local galaxies contain too many star-forming clumps, and they are also more centrally concentrated than clump clusters. Spiral and barred structure in local galaxies would still show up at high redshift too (using the HST ACS camera, for example), if the disk is not too faint to see.

UDF clump clusters have bigger and fewer clumps than local galaxies, even in the restframe uv, they have no symmetry or central concentration, and they are much brighter in restframe magnitudes. Typical clump clusters have surface brightnesses that are more than 10 times larger than the surface brightness of, for example, M101, which is a locally bright galaxy with lots of giant star-formation clumps (although the M101 clumps are still small by high redshift standards).

We may wonder if local flocculent spiral galaxies are a better match to high-z galaxies because local flocculents get most of their structure from gravitational instabilities in the gas and there are no prominent spiral waves in the old stellar disk. Two redshifted versions of the flocculent galaxy NGC 7793 were shown in Elmegreen et al. (2009b) and compared to GEMS galaxies. The local and distant galaxies do not look similar at all. In general, local galaxies are too smooth and too centrally concentrated compared to clump clusters.

On the other hand, a local dwarf Irregular galaxy is a good match to a clump cluster, although the clump clusters are much more massive (Elmegreen et al. 2009b). Clump clusters resemble local dwarf irregulars because both have high gas fractions, both have big complexes relative to the galaxy size, both have relatively thick disks, and both have high velocity dispersions relative to the rotation speed. Recall that LJeans / Galaxy Size ~ Hdisk / Galaxy Size ~ (sigma / V)2. That is, the clump size from gravitational instabilities is comparable to the galactic scale height, and the ratio of these lengths to the galaxy size is the square of the ratio of the velocity dispersion to the rotation speed. Thus big complexes, thick disks, and high dispersions (relative to galaxy size and rotation speed) all go together regardless of the galaxy mass.

Both local dwarf irregulars and clump clusters are irregular because they have a relatively high gas mass and a high sigma / V. Both are also relatively young in terms of the number of rotations they have lived and in terms of the relative gas abundance. The resemblance between clump clusters and local dwarfs is another example of down sizing: small galaxies today (dwarf irregulars) are doing what big galaxies (clump clusters) did at z ~ 2 (Elmegreen et al. 2009b).

There are other local galaxies that resemble clump clusters too, but they have about the same stellar mass as clump clusters, i.e., they are large galaxies. These local analogues are extremely rare, however. Casini & Heidmann (1976a, 1976b) and Maehara et al. (1988) discovered local "clumpy irregular galaxies" of normal size. Examples are Markarian 296, 325, 7, 8 (which are ultraviolet galaxies), and Kiso UV excess galaxies 1618+378, 1624+404, 1626+413, and Mrk 297. Maehara et al. (1988) determined galactic distances of 60 to 120 Mpc, clump sizes of ~ 2" (corresponding to 1 kpc), and clump absolute magnitudes of MB ~ -11 to -16 mag (corresponding to ~ 106 Lodot to 108 Lodot).

Garland et al. (2007) studied "Luminous Compact Blue Galaxies." These are small, high luminosity, high surface brightness galaxies with a blue color. They are also gas-rich (CO, HI), like high-z galaxies, and rotating with distorted velocities, as if they are interacting or lopsided. Overzier et al. (2008, 2009, 2010) studied Lyman Break Analogs (Heckman 2005). These are super-compact uv-luminous galaxies. They are GALEX objects with LFUV > 1010.3 Lodot and intensities IFUV > 109 Lodot kpc-2 at redshifts z < 0.3. They are also very rare ( ~ 10-6 Mpc-3).

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