Nick Indriolo

Graduate Student
The University of Illinois at Urbana-Champaign

Education

Research

The main focus of my research is studying H₃⁺ in the interstellar medium. We have searched for H₃⁺ in 23 diffuse cloud sightlines and detected it in 14 of those. Coupled with other various measurements and some assumptions, these observations can be used to infer the cosmic-ray ionization rate. Current results suggest that the ionization rate in diffuse clouds is about one order of magnitude larger than prevsiously thought. A higher ionization rate will result in some different chemistry occurring in diffuse clouds, so we are continuing to study more sightlines to get better constraints.

I have begun to approach the cosmic-ray question from a theoretical standpoint as well. Working with Brian Fields, I am attempting to calculate the ionization rate starting from some assumed cosmic-ray energy spectrum. In addition to ionization though, cosmic rays also produce light elements via spallation and gamma rays via excitation of nuclear states. We are testing several physically motivated cosmic ray spectra to see if they can reproduce inferred ionization rates, observed LiBeB abundances, and gamma ray fluxes. In this way, we hope to put some constraints on the cosmic ray spectrum below ~1 GeV, which is otherwise unobservable.

My undergraduate research at CWRU dealt with using dynamical tracers such as planetary nebulae and globular clusters in M31 to learn more about different populations within the galaxy. I used data from the SAURON two-dimensional spectrograph to create a model for the expected position vs. velocity plot for an isotropic oblate rotator. By comparing these generated plots to the actual data, I could attempt to assign objects to the disk, bulge, or other populations. An overview can be found at my old web page.

Other previous research involved using the high power radar system at MIT Haystack Observatory to examine the flux of micrometeors through the Earth's ionosphere. This project was part of a summer REU program sponsored by the NSF.

Publications

Indriolo, N., Geballe, T. R., Oka, T., & McCall, B. J. 2007, ApJ, 671, 1736

Conference Presentations

Indriolo, N., Fields, B. D., McCall, B. J. "Constraining the Low-Energy Cosmic-Ray Spectrum" 63rd Ohio State University International Symposium on Molecular Spectroscopy. 2008

Indriolo, N., McCall, B. J., Geballe, T., & Oka, T. "H₃⁺ in Diffuse Interstellar Clouds: A Tracer for the Cosmic-Ray Ionization Rate" 62nd Ohio State University International Symposium on Molecular Spectroscopy. 2007

Links