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  Laura's Research  
  EVLA Radio Observations of Novae  

The newly-upgraded Expanded Very Large Array (EVLA) is capable of producing radio light curves of unprecedented depth and frequency coverage. We, the EVLA Nova Project, are observing all bright Galactic novae observable with the EVLA (dec > -35°) over the frequency range 1--35 GHz. The radio emission from novae is expected to be thermal free-free emission from the expanding ejecta. Our goals are to determine fundamental properties of the explosion (e.g., ejecta mass, energy), while searching for other possible emission components (both thermal and non-thermal) that may be the signatures of collimated outflows or interaction with a circum-binary medium. These data are complimented by a suite of other wavelengths, including optical and X-ray. Check here for recent results!

  EVLA Constraints on the Environments---and Progenitors---of Type Ia Supernovae  

SNe Ia are believed to be the explosion of a near-Chandrasekhar mass white dwarf made of carbon and oxygen; to reach such high masses, the white dwarf must have accreted from a binary companion of some kind, but the nature of this companion remains a mystery. It may be a main sequence or giant star, or another white dwarf. As the white dwarf accretes from its companion star, some material is expected to be lost during this process and surround the system. However, most searches for such circum-binary material have yielded non-detections, and the expected signal from the predicted medium is just beyond their reach. We have undertaken the most sensitive search to date for circum-binary material around SNe Ia, searching for radio continuum emission with the remarkably sensitive EVLA. We observe all SNe Ia within 30 Mpc as soon as possible after explosion, including the recent SN 2011fe in M101 (observed just two days after explosion!).

  Exotic Transients in Pan-STARRS1  

New wide-field time-domain surveys like Pan-STARRS1 are uncovering new classes of astronomical transients. Recently, I carried out a study of two ultra-luminous SNe at a redshift of 0.9; these spectacular explosions show no evidence for H or He in their spectra, and the source of their extroardinary energy remains a mystery. We are following up many of these new classes of explosions with the EVLA as part of an NRAO Key Project, searching for radio emission that can shed light on the explosion mechanism and the environment of the progenitor.

  Intermediate Mass Black Holes in Globular Clusters  

While there is some evidence for intermediate-mass black holes (IMBHs) in globular clusters based on dynamical work, these claims are often of low significance and hotly debated. We can also search for IMBHs via their accretion signatures, and radio emission should be a particularly efficient tracer of such low-level accretion. We have embarked on a program of deep radio imaging of several Galactic globular clusters with the EVLA to search for such an accretion signature; we reach an rms sensitivity of 1.5 μJy/beam in 10 hours of observing time and place some of the deepest limits on IMBH mass.

  The Link between Star Formation and Synchrotron Emission in Nearby Galaxies  

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