A Survey of Starburst Galaxies

An effort to help understand the starburst phenomenon and its importance to galaxy evolution

Megan Sosey & Duilia deMelloMarch 2, 2006

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

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

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

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

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

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

Final SampleThere will be two main components

(i) A magnitude limited sample(ii) 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

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

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

NGC 3690V=3033

NGC2798 v=1739Interaction withNGC2799 v=1673

NGC 3448 v=13501 companion at 3.9’V=1493 (UGC6016)

NGC 4194 v=2506 no companion within one degreeat similar velocity

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

Preliminary Results