Starburst Galaxies

1. A Survey of Starburst GalaxiesAn effort to help understand the starburst phenomenon and its importance to galaxy evolutionMegan Sosey & Duilia deMelloMarch 2, 2006

2. Starburst Galaxies • Galaxies going through active, ongoing star formation • The “burst” dominates the luminosity of the galaxy • Contain massive hot stars which dominate the galaxies energetics from the farUV to the near IR. • Emission-line spectra, blue optical colors and far-IR colors are commonly used in diagnostics and classification • Good laboratories for investigating the physical processes occurring in star-forming regions locally and in the early universe

3. Questions to be answered? • Do all galaxies go through starburst phase? • What are the mechanisms required to start and stop star-formation? Interaction? Environment? • Are starbursts the local analog of high-redshift star forming galaxies such as Lyman Break galaxies? • How much of the intergalactic medium is enriched by outflows from starbursts? • How is the SFR or stellar mass budget distributed amongst galaxies of different types and masses

4. Why is this study important? • The definition of starburst is not well constrained in the literature • The available data is highly uneven, some objects have been studied more extensively, and in more wavelengths than others • Multi-wavelength data is essential because galaxies appear different depending on the emission mechanism that dominates their radiation; It will help properly evaluate the overlap between the starburst population and high-redshift star-forming galaxies

5. Initial Project Goals • Produce a color selected sample of star-forming galaxies from the SDSS • Identify a set of physical conditions and the chronology of events which lead to the starburst • Build a multi-wavelength database using the VO which is accessible to the community and can evolve as new observations are made available

6. Sample Selection • Samples of starbursts derived from UV spectral observations exist in the literature • Atlas of UV-to-FIR magnitudes for 83 starburst galaxies (Wu+, 2002; Kinney 1993) • Common objects are selected from the SDSS • We determine the SDSS colors that these galaxies have and use color-color and color-magnitude diagrams to select all galaxies in the SDSS with similar colors, in order to derive a statistical sample

7. Sample Contamination • Biased against dusty galaxies that are IR luminous • The nature of the underlying source is unknown and could be an AGN • AGN’s themselves might bias the sample, so a comparison against known star-forming galaxies in the SDSS must be performed • Control samples of isolated galaxies, mergers and pairs taken from SDSS will be used for comparison

8. Final Sample There will be two main components • A magnitude limited sample • A distance limited sample based on redshifts taken from SDSS Objects can be classified as a function of luminosity, stellar mass, metallicity and total gas -our sample criteria should allow us to find more than 1,000 objects in the SDSS

9. Analyze AND manage the data? • The VO is an excellent resource for information and analysis • Interconnected tools provide an easy interface between available data and scientific analysis • The convenience of the internet allows a unique opportunity to create an evolving data warehouse, easily accessible to the community, and easy to update as new data is made available

10. Examining the Environment around starburst galaxies • Interactions may be important for triggering activity in galaxies • How is the star formation efficiency correlated with the environment where galaxies reside? • Investigate galaxy properties by comparing SFR, metallicity, stellar mass in low and high density environments

19. NGC 3690 V=3033

20. NGC2798 v=1739 Interaction with NGC2799 v=1673

21. NGC 3448 v=1350 1 companion at 3.9’ V=1493 (UGC6016)

22. NGC 4194 v=2506 no companion within one degree at similar velocity

26. Preliminary Results --- Mergers (Allam et al. 04) --- Karachentseva isolated galaxies