Do high energy astrophysical neutrinos trace star formation?

The IceCube Neutrino Observatory has provided the first map of the high energy (~ 0.01 -- 1 PeV) sky in neutrinos. Since neutrinos propagate undeflected, their arrival direction is an important identifier for sources of high energy particle acceleration. Reconstructed arrival directions are consistent with an extragalactic origin, with possibly a galactic component, of the neutrino flux. We present a statistical analysis of positional coincidences of the IceCube neutrinos with known astrophysical objects from several catalogs. When considering starburst galaxies with the highest flux in gamma-rays and infrared radiation, up to n=8 coincidences are found, representing an excess over the ~4 predicted for the randomized, or null distribution. The probability that this excess is realized in the null case, the p-value, is p=0.042. This value falls to p=0.003 for a partial subset of gamma-ray-detected starburst galaxies and superbubble regions in the galactic neighborhood. Therefore, it is possible that starburst galaxies, and the typically hundreds of superbubble regions within them, might account for a portion of IceCube neutrinos. The physical plausibility of such correlation is discussed briefly.

Active Galactic Nuclei and their role in Galaxy Formation and Evolution

There are several key open questions as to the nature and origin of AGN including: 1) what initiates the active phase, 2) the duration of the active phase, and 3) the effect of the AGN on the host galaxy. Critical new insights to these can be achieved by probing the central regions of AGN with sub-mas angular resolution at UV/optical wavelengths. In particular, such observations would enable us to constrain the energetics of the AGN feedback mechanism, which is critical for understanding the role of AGN in galaxy formation and evolution. These observations can only be obtained by long-baseline interferometers or sparse aperture telescopes in space, since the aperture diameters required are in excess of 500 m - a regime in which monolithic or segmented designs are not and will not be feasible and because these observations require the detection of faint emission near the bright unresolved continuum source, which is impossible from the ground, even with adaptive optics. Two mission concepts which could provide these invaluable observations are NASAs Stellar Imager (SI; Carpenter et al. 2008 & http://hires.gsfc.nasa.gov/si/) interferometer and ESAs Luciola (Labeyrie 2008) sparse aperture hypertelescope.