Record Details

Exploring the Connection Between Star Formation and AGN Activity in the Local Universe
NTRS Full-Text: Click to View  [PDF Size: 981 KB]
Author and Affiliation:
LaMassa, Stephanie M.(Johns Hopkins Univ., MD, United States);
Heckman. T. M.(Johns Hopkins Univ., MD, United States);
Ptak, Andrew(NASA Goddard Space Flight Center, Greenbelt, MD, United States);
Schiminovich, D.(Columbia Univ., NY, United States);
O'Dowd, M.(Lehman (Herbert H.) Coll., Bronx, NY, United States);
Bertincourt, B.(Columbia Univ., NY, United States)
Abstract: We study a combined sample of 264 star-forming, 51 composite, and 73 active galaxies using optical spectra from SDSS and mid-infrared (mid-IR) spectra from the Spitzer Infrared Spectrograph. We examine optical and mid-IR spectroscopic diagnostics that probe the amount of star formation and relative energetic con- tributions from star formation and an active galactic nucleus (AGN). Overall we find good agreement between optical and mid-IR diagnostics. Misclassifications of galaxies based on the SDSS spectra are rare despite the presence of dust obscuration. The luminosity of the [NeII] 12.8 micron emission-line is well correlated with the star formation rate (SFR) measured from the SDSS spectra, and this holds for the star forming, composite, and AGN-dominated systems. AGN show a clear excess of [NeIII] 15.6 micron emission relative to star forming and composite systems. We find good qualitative agreement between various parameters that probe the relative contributions of the AGN and star formation, including: the mid-IR spectral slope, the ratio of the [NeV] 14.3 micron to [NeII] micron 12.8 fluxes, the equivalent widths of the 7.7, 11.3, and 17 micron PAH features, and the optical "D" parameter which measures the distance a source lies from the locus of star forming galaxies in the optical BPT emission-line diagnostic diagram. We also consider the behavior of the three individual PAH features by examining how their flux ratios depend upon the degree of AGN-dominance. We find that the PAH 11.3 micron feature is significantly suppressed in the most AGN-dominated systems.
Publication Date: Jun 25, 2012
Document ID:
(Acquired Apr 22, 2013)
Subject Category: ASTROPHYSICS
Report/Patent Number: GSFC-E-DAA-TN7966
Document Type: Preprint
Financial Sponsor: NASA Goddard Space Flight Center; Greenbelt, MD, United States
Organization Source: NASA Goddard Space Flight Center; Greenbelt, MD, United States
Description: 51p; In English; Original contains color and black and white illustrations
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
Miscellaneous Notes: to be published in The Astrophysical Journal, 2013
› Back to Top
Facebook icon, External Link to NASA STI page on Facebook Twitter icon, External Link to NASA STI on Twitter YouTube icon, External Link to NASA STI Channel on YouTube RSS icon, External Link to New NASA STI RSS Feed
Find Similar Records
NASA Logo, External Link

NASA Official: Gerald Steeman

Sponsored By: NASA Scientific and Technical Information Program

Site Curator: STI Support Services

Last Modified: April 22, 2013

Privacy Policy & Important Notices Disclaimers, Copyright, Terms of Use Freedom of Information Act NASA OCIO Free Adobe PDF Reader Free MS Word Viewer