Science is successful because the physical laws we discover on Earth work everywhere and everywhen. We use laboratory experiments to expand our understanding of physical processes and then apply these results to processes throughout the Universe.
ProtoEXIST is a balloon-borne wide-field hard X-ray survey project, which is a prototype experiment for a next generation hard X-ray survey mission - the Energetic X-ray Imaging Survey Telescope (EXIST). EXIST was recommended by the 2001 Decadal Survey and further developed as a candidate for Black Hole Finder Probe (BHFP) under the NASA Beyond Einstein program and then for the 2010 Decadal Survey.
In astrophysics most of the X-ray emission is produced either by one of two processes. Stellar coronae, supernova remnants, galaxies and clusters of galaxies show emission features primarily produced by collisions between electrons and ions. Black holes and neutron stars produce strong high energy continuum emission by unknown processes; this emission in turn photoionizes the surrounding environment. We look through this environment and may see emission or absorption features implanted on the continuum.
Laboratory experiments help us to ensure that we are using the best atomic data to interpret astrophysical observations. X-ray observations at both high and low resolution require accurate and complete atomic databases for modeling. Experiments conducted by CfA scientists can help in the identification of spectral lines. Furthermore, the ratio of two lines from the same element and ionization state can give an independent measurement of density or temperature, as determined in a laboratory experiment.
The HITRAN compilation of the SAO (HIgh resolution TRANmission molecular absorption database) is used for predicting and simulating transmission and emission of light in atmospheres. It is the world-standard database in molecular spectroscopy. The journal article describing it is the most cited reference in the geosciences. There are presently about 5000 HITRAN users world-wide.
AMP laboratory measurements of exotic carbon-chain molecules aim to understand the role of the chemical bond and organic chemistry in nature on a cosmic scale, and to determine the origin of the interstellar diffuse bands, the outstanding unsolved problem in astronomical spectroscopy.
A plasma is an ionized gas consisting of ions (atoms with some of their electrons removed) and free electrons. Hot plasmas are found throughout the universe: in the magnetic field structures above the surface of stars like the Sun, in the media between stars and galaxies, and in the surroundings of an exploded star known as a supernova remnant. Highly ionized gas is also found in the environments surrounding black holes.
Over 140 molecules have been identified in the interstellar gas and circumstellar shells, the largest among them a carbon chain with 13 atoms and a molecular weight of 147 (twice that of the simplest amino acid glycine). Astronomers in the RG and AMP divisions carry out such measurements in a laboratory equipped with two unique instruments: a free space millimeter-wave absorption spectrometer and a Fourier transform microwave (FTM) spectrometer used in combination with a supersonic molecular beam.
Theoretical studies support astronomical observations at all wavelengths, directly address topics of astrophysical importance, and pursue related studies in fundamental physics and atmospheric science.