Dr. Stephen Muchovej is awarded an NSF Astronomy and Astrophysics Postdoctoral Fellowship to carry out a program of research and education at the California Institute of Technology. Dr. Muchovej will perform a multi-wavelength study of the interstellar medium (ISM) incorporating the C-Band All Sky Survey (CBASS), with emphasis on characterizing polarized foregrounds and the nature of the "anomalous emission" component of current ISM models. CBASS is an NSF-funded, 5-GHz radio survey sensitive to total intensity and linear polarization that will produce the first all-sky map of polarized emission that can be reliably extrapolated to frequencies of interest to cosmic microwave background (CMB) polarization experiments. In conjunction with the CBASS map, Dr. Muchovej will combine public H-alpha (a tracer of free-free emission), Wilkinson Microwave Anisotropy Probe (WMAP) (CMB radio frequencies), and Infrared Astronomical Satellite (IRAS) (dust) data to identify and study regions exhibiting dust-correlated anomalous emission at ~30 GHz. Infrared and microwave observations will be used to study the mechanisms producing the anomalous emission and its role in the ISM as a whole.
Dr. Muchovej will also develop a prototype for a millimeter-wave monolith integrated (MMIC) Array Spectrograph (MAS), the precursor to focal-plane arrays of detectors capable of wide-field imaging and spectroscopy from 30-100 GHz.
In addition, Dr. Muchovej will conduct an outreach program targeted at teaching astronomy to children ages 4-12 through the development and implementation of hands-on activities that promote physical understanding on a wide range of topics in astronomy. Dr. Muchovej will translate his materials into Spanish and Portuguese and will implement them both near Caltech and in Latino community centers in the greater Los Angeles area.
The primary scientific goal of this project was to further our understanding of foreground emission as it pertains to observations of the Cosmic Microwave Background (CMB). The CMB is the light left-over from the Big Bang, and recent studies of its properties have provided us with a wealth of knowledge about the Universe. To gain as much as possible from studies of the CMB, astronomers must accurately account for all sources of emission between us and this light -- effectively account for everything that emits in the Universe. In this project, we characterized the abundance of compact extra-galactic sources of emission at centimeter wavelengths, and found their density to be roughly twice what had been expected from theoretical predictions and observations performed at lower frequencies. This project also supported the construction of a novel telescope aimed at studying the inter-stellar medium (ISM) of our own Galaxy. In particular, we built a new telescope to measure the intensity and polarization of our Galaxy at 5GHz. The first Figure shows maps of two regions of our Galaxy, namely the Crab Nebula (known to be polarized) and DR21 (a star forming region known to be unpolarized), obtained from our new telescope. This project also partook in direct studies of the CMB by studying individual clusters of galaxies with the Sunyaev-Zel'dovich Array, discovering properties of the largest structures in the Universe. Applying methods for source-extraction derived in this project to a radio survey of a small patch of sky, a meaningful cosmological constraint on the mass density fluctuations in the Universe was placed. The result derived here is consistent with other ground-based and space-based experiments, and further corroborate the presence of a form of energy responsible for the expansion of the Universe, known as Dark Energy. This project is unique in that it also included a large amount of support for synergistic and educational aspects. The primary educational goal of this project was to introduce astronomy to young children, and exploit their inherent curiosity to help improve scientific understanding from an early age. This involved bi-monthly classroom visits where hands-on activities about astronomy were presented to elementary school children. We also worked on curriculum development for teaching children critical thinking and the scientific method. Additionally, the support received through this grant allowed for the expansion of outreach activities of the Owens Valley Radio Observatory (OVRO) to the adult community via an extremely popular public lecture series (See Attached Announcement), increased number of observatory tours, and star-parties in sparsely populated areas. To obtain more information on our outreach efforts at the observatory, please visit www.ovro.caltech.edu.
