8th HEAD Meeting, 8-11 September, 2004
Session 26 AGN/Galactic Nuclei
Poster, Friday, September 10, 2004, 9:00am-10:00pm

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[26.11] The High Energy Emission of the Nearest Ultra-luminous Infrared Galaxy (Arp 220)

D. F. Torres (Lawrence Livermore National Laboratory)

Our current understanding of ultraluminous infrared galaxies (ULIRGs) suggest that they are recent galaxy mergers in which much of the gas in the former spiral disks, particularly that located at distances less than 5 kpc from each of the pre-merger nuclei, has fallen into a common center, triggering a huge starburst phenomenon. This large nuclear concentration of molecular gas has been detected (using CO and HCN lines) by many groups, and estimates of molecular mass and density have been made. Not surprisingly, these were found to be orders of magnitude larger than the corresponding values for these quantities found in our Galaxy. In Arp 220, a supernova seems to explode at least once every six months, and several individual SNRs are visible at any given moment.

In this contribution, the first self-consistent model of the high energy emission of the super-starburst galaxy Arp 220 is presented. The model provides an estimate of the radio emission of each of the components of the central region of the galaxy (western and eastern extreme starbursts, and molecular disk). The predicted radio spectrum is found a) as a result of the synchrotron and free-free emission, and absorption, of the primary and tertiary steady population of electrons and positrons, output of charged pion decay in proton-proton interactions, and subject to a full set of losses in the ISM and b) in agreement with sub-arcsec radio observations. Estimates of the magnetic field in the central regions of Arp 220 are herein given for the first time. In addition, the FIR emission is modeled with dust emissivity, and the computed FIR photon density is used as a target for inverse Compton process. Bremsstrahlung emission and neutral pion decay are also computed, and the gamma-ray spectrum is predicted. Future possible observations with GLAST, and the ground based Cherenkov telescopes are discussed.

If you would like more information about this abstract, please follow the link to http://www.angelfire.com/id/dtorres. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: dtorres@igpp.ucllnl.org

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© 2004. The American Astronomical Soceity.