Observational and Theoretical Studies of Variability in     Compact Extragalactic Sources
{'Code': '03020400', 'Directorate': {'Abbreviation': 'MPS', 'LongName': 'Direct For Mathematical & Physical Scien'}, 'Division': {'Abbreviation': 'AST', 'LongName': 'Division Of Astronomical Sciences'}}
{'SignBlockName': 'Millissa J. Evans', 'PO_EMAI': None, 'PO_PHON': None}
The variations observed in compact extragalactic radio                          sources will be investigated both observationally and                           theoretically. These variations manifest themselves as changes                  both in the structure as revealed by very-long baseline                         interferometry (VLBI)studies and in the total flux density.  The                VLBI technique will be used to monitor two quasars, 4C39.25 and                 NRAO 140, which are under going particularly interesting                        variations which may also lead to new understandings of phenomena               previously observed.                                                                                                                                            Investigations of theoretical explanations for the observed                     variability in quasars and similar sources will be carried out.                 Models involving shock waves propagating through turbulent                      regions in relativistic jets appear capable of explaining the                   general characteristics of the observed variations, especially                  the frequency dependence of the variability timescales. Numerical               calculations of emission patterns and spectra of shocks in                      turbulent jets will be performed and compared with                              the observational data.                                                                                                                                         The ultimate goal of the proposed project is to better                          understand the nature and origin of high-speed compact jets in                  quasars, and through this the nature of the "central engine" in                 these objects.
{'FirstName': 'Alan', 'LastName': 'Marscher', 'PI_MID_INIT': 'P', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'Alan P Marscher', 'EmailAddress': 'marscher@bu.edu', 'NSF_ID': '000156232', 'StartDate': '02/01/1989', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'Trustees of Boston University', 'CityName': 'BOSTON', 'ZipCode': '022151703', 'PhoneNumber': '6173534365', 'StreetAddress': '1 SILBER WAY', 'StreetAddress2': None, 'CountryName': 'United States', 'StateName': 'Massachusetts', 'StateCode': 'MA', 'CONGRESSDISTRICT': '07', 'CONGRESS_DISTRICT_ORG': 'MA07', 'ORG_UEI_NUM': 'THL6A6JLE1S7', 'ORG_LGL_BUS_NAME': 'TRUSTEES OF BOSTON UNIVERSITY', 'ORG_PRNT_UEI_NUM': None}
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{'Code': '121700', 'Text': 'EXTRAGALACTIC ASTRON & COSMOLO'}
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1988&All=true', 'xml': '8815848.xml'}