SRAVANI VADDI, RIT

Sravani Vaddi1, Chris O’Dea1, Stefi Baum1, Christine Jones2,

Bill Forman2, Samantha Whitmore3 and Rabeea Ahmed3

1Astrophysical Sciences & Technology, RIT2Harvard-Smithsonian Center for Astrophysics

3Harvard University

FEEDBACK IN THE LOCAL UNIVERSE:THE RELATION BETWEEN STAR FORMATION

AND AGN ACTIVITY IN ELLIPTICAL GALAXIES

SRAVANI VADDI, RIT

AGN - Active Galactic Nucleus

• AGN - Class of galaxies showing energetic phenomena at the center of the galaxy.

• Proposed by Hoyle and Fowler(1963).

Fig: AGN Model

SRAVANI VADDI, RIT

MULTI-WAVELENGTH IMAGES OF AGN

INFRARED

Centaurus A galaxy. Credit: X-ray: Chandra; Radio: VLA; Optical: ESO

Hydra A galaxy

SRAVANI VADDI, RIT

MOTIVATION

Credit: Simon Driver

Fig: Galaxy Luminosity Function. Simply a distribution of galaxies

Theory predicts large number of bright/massive galaxies.

But observations indicate that there are very few bright galaxies.

Some mysterious energy is preventing star formation.

Galaxy brightness

Bright Faint

Num

ber d

ensit

y

TheoryObservations

SRAVANI VADDI, RIT

• Jets from the AGN prevent cooling of the gas by pushing away the gas.

• This reduces star formation.

Hydra A. Credit: X-ray: Chandra Telescope; Radio: VLA; Optical: Canada-France-Hawaii-Telescope

POSSIBLE SOLUTION – AGN FEEDBACK

SRAVANI VADDI, RIT

AGN feedback is observed in distant galaxies.

THEN, Is it still ongoing? How powerful is AGN activity in the nearby

galaxies? How does it affect star formation in these

galaxies if at all it does?

THE PROJECT

SRAVANI VADDI, RIT

Maximum radio power from the AGN is dependent on the mass of the galaxy.

Massive galaxies are capable of hosting powerful radio sources.

This is consistent with AGN feedback shaping the high mass end of galaxy LF.

RESULT 1 – RADIO POWER AND GALAXY MASS RELATION

CONCLUSION & FUTURE WORK

CONCLUSION

• We notice that AGN feedback is ongoing in the local universe.

• AGN activity is not very powerful and prominent in the nearby galaxies as compared to distant galaxies.

• AGN activity does seem to influence star formation via feedback, BUT, it is not the only process involved in reducing star formation.

FUTURE WORK

• How much feedback is affecting star formation. What are the other processes?

• Quantitative analysis for this work needs to be done such as calculating star formation rate, efficiency of accretion.

SRAVANI VADDI, RIT