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Minutes of the talk on the:
      SMUDGES Survey

Liese van Zee (Indiana U.)


SMUDGES = Systematic Multiwavelength Unbiased catalog of Dwarf Galaxies and Evolution of Structure.

This survey will using the 3.5 and 0.9m telescopes of the WIYN Observatory to conduct an unbiased survey for dwarf galaxies.

Science questions:

Isolated LSBDG's exhibit a huge dynamic range of star formation activity so what's needed is an unbiased catalog of dIs.

Key goals:

Survey requirements:

Survey design

DGs are small and faint with diameters of ~0.5 kpc and absolute magnitudes MB ~ -12. At 100 Mpc, such a galaxy subtends only 1 arcsec and has an apparent magnitude mB ~ +23. Therefore, you need to survey a large area to have a sufficient volume to find enough dwarfs. So this criterion is similar to that for HI surveys, and likewise one must worry about beam filling factors.

First results: discovery of a dE in the field

In one of our first runs, we have identified a small dE galaxy characterized by mB = 21, (B-I) = 1.8, z = 0.003, MB = -9.4. This is a very small galaxy. It is isolated, no (known) nearby neighbors (yet), though we still need redshifts for some of the HSB objects in this field.

From SMUDGES, we hope to learn about the role of environment in the evolution of dwarf galaxies and, in particular, how dE's are formed in isolated regions.

Project design

Determination of both the HI mass function and the optical LF function, and how those two might be related, is really important.


Questions/Discussion

Peppo G: What is typical the HI mass and distribution of IZw18 and U2684?
Liese Both have about 108 solar masses of HI. 1Zw18 is an extensive HI object with a "tail" and a companion which HI extends very far. UGC 2684 is a more typical dwarf. HI goes out twice as far as optical.
Judith I. Is the ALFALFA survey as described sufficient to detect dwarfs?
Liese You want to be sensitve down to 106 solar masses in the nearest volume, so 1 min or less with Arecibo achieves that out to 20 Mpc.
Wim vD 106 solar masses at Virgo is quite a long integration.
Liese But increasing the area is better so we have to compromise.
Riccardo G. Are there any objects with total HI masses of 106 solar masses which have been discovered previously?
Liese In the Local Group, the dwarfs go down to 107 solar masses. Low mass galaxies are very rare, so we need to cover a lot of area.


next up previous
Next: Ly-alpha survey Up: Minutes of the 1st Previous: Jodrell Virgo Survey


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Last modified: Thu Apr 17 18:21:39 EDT 2003