Mid-IR High Ionization Lines in Starbursts Lei Hao Spitzer IRS Team Cornell University

The Spitzer Telescope Infrared Spectrograph (IRS) Low resolution modules (SL,LL) –5-40  m wavelength coverage –Resolution: High resolution modules (SH, LH) –9-38  m wavelength coverage –Resolution: 600 Data –IRS of ~40 Nearby famous AGN and starbursts (Weedman et al. 2005, Brandl et al. 2005, in prep) –62 BCDs/11 IRS spectra (Wu et al 2005, submitted) –This talk: high resolution spectra of 11 BCDs +17 Starbursts (no AGN components)

Mid-IR Fine Structure Emission lines Less affected by extinction Photoionized by massive stars [OIV] in starbursts –Requires eV, just above the HeII edge –Weaker than in AGNs, ULIRGs –Shocks, super-hot stars, weak AGN [NeV] in starbursts –Not observed in pure starburst, an indication of AGN presence

Mid-IR Fine Structure Emission lines

Results 11 BCDs + 17 Starbursts (no AGN component) [OIV] is ubiquitous –7/11 BCDs and 15/17 Starbursts

Results [NeV] is positively detected in three objects –1/11 BCDs and 2/17 Starbursts CG0752 NGC2623 NGC4194

Results

Origin of the High Ionization Lines Photoionization –Starburst99+Mappings

Origin of the High Ionization Lines Shock? by Lisa Kewley