Savin Group - Selected Research Interests
First star formation
Cosmic origins of organic chemistry
Winds from black holes
The Solar wind
First star formation
The formation of the first stars and protogalaxies was mediated by H2 which is an important coolant in primordial clouds. Understanding the hydrogen chemistry leading to the generation of H2 is therefore critical to reliably modeling the formation of the first stars and protogalaxies. Current theoretical and experimental uncertainties in this chemistry limit our understanding of protogalaxy formation and of the characteristic masses and cooling times for the first stars. We are carrying out a series of laboratory measurements for several of the key reactions which control the H2 abundance during this epoch.
Cosmic origins of organic chemistry
Organic chemistry began in interstellar gas clouds where atomic carbon was "fixed" into molecules, thereby initiating the synthesis of complex organic species which gave rise eventually to the solid material that helped to build planets. Much of our knowledge of this cosmic pathway towards life derives from radio-frequency spectroscopy of molecular clouds which require sophisticated astrochemical models to interpret the observations. However, breakthroughs in our understanding of the molecular universe are limited by uncertainties in the underlying chemical data in these models. Of particular importance are data for reactions of neutral atomic carbon atoms with molecular ions which are critical in initiating interstellar organic chemistry. Theory is limited to classical methods as fully quantum mechanical reactions for systems with four or more atoms are beyond computational capabilities now and for the foreseeable future. Existing laboratory experiments have produced ambiguous results owing to the extraordinary challenge of generating and characterizing atomic carbon beams. We are currently building a unique laboratory instrument to produce well characterized C beams which we will merge with various molecular ions to study the cosmic origins of organic chemistry, largely free from the limitations of previous experimental methods.
Winds from black holes
Recent X-ray satellite spectroscopic observations by Chandra and XMM-Newton of active galactic nuclei (AGNs) have detected a previously unobserved set of spectral features. These features are attributed to the winds emanating from the supermassive black hole lurking in the center of each AGN. However, our ability to reliably interpret these features to infer the properties of this wind and the embedded black hole is limited by uncertainties in our understanding of the atomic physics which produces the observed spectrum. Especially important is determining correctly the ionization structure of the gas. This in turn depends on understanding the electron-ion recombination process known as dielectronic recombination (DR).

To study the relevant recombination processes, my group and our collaborators at the Max Planck Institute for Nuclear Physics (MPIK) and the University of Giessen, Germany, are carrying out a series of DR measurements. The efforts of my collaborators are being led by Prof. Dr. Andreas Wolf at MPIK and of Prof. Dr. Alfred Müller and Prof. Dr. Stefan Schippers at Giessen. Measurements are carried out using the heavy-ion test storage ring (TSR) at the MPIK in Heidelberg, Germany.

The solar wind
Investigating the dynamics of the solar corona is crucial if one is to understand fundamental solar and heliospheric physics. The corona also greatly influences the Sun-Earth interation as it is from here that the solar wind originates. The solar wind can have a profound effect on the Earth's magnetosphere and ionosphere, disrupting power grids and commmunication. Hence characterizing the origins of the solar wind is of obvious importance. This is done, in part, through a combination of solar spectroscopic observation, spectral analysis codes, and theoretical models for the transport of energy and particles from the photosphere through the corona and into the solar wind.

Recently we have developed a new approach for analyzing solar spectra which yields more reliable determinations for the relative elemental abundances in the corona. We are also carrying out a series of DR and electron impact ionization measurements using TSR so that we can generate more accurate ionization balance calculations of the corona and thereby better spectral models.

Last updated: 21 November 2009. © Savin Research Group 2009