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FERMI-LAT GEV OBSERVATIONS HAVE REVEALED A LARGE POPULATION OF ENERGETIC MILLISECOND PULSARS (MSP) IN SHORT PERIOD (PB<1D) BINARIES WHERE THE PULSAR SPIN-DOWN POWER IS DRIVING A MASSIVE WIND FROM A COMPANION. THESE `BLACK WIDOW'-TYPE PULSAR'S COMPANIONS ARE LOW MASS MAIN SEQUENCE STARS OR SUB-STELLAR (PLANETARY MASS) REMNANTS; THE LATTER ARE ONLY VISIBLE VIA THE DRAMATIC PULSAR HEATING. THE WIND OFTEN OBSCURES THE RADIO PULSAR EMISSION SO THAT THE PENETRATING GAMMA-RAYS WERE CRUCIAL IN SPURRING THE DISCOVERY OF THESE OBJECTS. THIS PREVIOUSLY HIDDEN POPULATION AFFORDS A NEW WINDOW ON CLOSE BINARY EVOLUTION AND HIGH ENERGY PULSAR PHYSICS AND THE COMMUNITY HAVE OBTAINED EXTENSIVE X-RAY OBSERVATIONS TO STUDY THE COUNTERPARTS. THIS IS IMPORTANT SINCE WHILE THE GEV (AND RADIO) EMISSION IS DOMINATED BY THE PULSAR MAGNETOSPHERE THE X-RAY LIGHT CURVES CAN SHOW SIGNATURES OF SYNCHROTRON EMISSION FROM THE RELATIVISTIC INTRABINARY SHOCK (IBS) BETWEEN THE PULSAR POWER AND THE COMPANION WIND. THIS IBS IS CRUCIAL IN REPROCESSING THE PULSAR POWER AND DELIVERING ENERGY TO HEAT THE `DAY TIME' FACE OF THE COMPANION. WE PROPOSE A PROGRAM OF UNIFORM ANALYSIS OF THE EXTENSIVE (>3MS) ARCHIVE EXPOSURE OF OVER 30 COMPANION-EVAPORATING PULSAR BINARIES. XMM AND CHANDRA PROVIDE (BY PHOTON COUNT AND EXPOSURE) THE DOMINANT DATA SETS BUT SWIFT SUZAKU NUSTAR ETC. DATA SETS WILL ALSO BE IMPORTANT FOR THIS STUDY. WE WILL GENERATE MULTI-MISSION LIGHT CURVES IBS FLUXES AND FOR THE BRIGHTER SOURCES PHASE AND EPOCH-RESOLVED SPECTRA PROBING THE SYNCHROTRON EMISSION FROM HIGH ENERGY PARTICLES IN THE IBS. THIS WILL BE SUPPLEMENTED BY ANALYSIS OF OPTICAL DATA (OURS AND OTHER PUBLISHED RESULTS) PROBING THE LOWER ENERGY IBS EMISSION AND THE COMPANION HEATING. WE WILL ALSO ANALYZE THE LAT DATA TO DETECT OR PLACE CONSTRAINTS ON COMPTON EMISSION FROM THE IBS SHOCKS. THESE DATA WILL BE UNIFORMLY ADDRESSED BY OUR IBS BINARY MODEL CODE WHICH CAN FIT TO CONSTRAIN THE CRUCIAL PARAMETERS DESCRIBING THE SYSTEM GEOMETRY PULSAR HEATING POWER AND EARTH VIEWING ANGLE. THESE WILL ALLOW US TO DETERMINE COMPANION ROCHE LOBE FILL FACTORS WIND MASS DRIVING RATES AND BINARY COMPONENT MASSES. IN TURN THE SURVEY PROBES THE POORLY UNDERSTOOD PHYSICS OF THE EVAPORATION PROCESS THE CONNECTION WITH THE PARENT X-RAY BINARY POPULATION PROPOSED EVOLUTION BETWEEN THE SEVERAL CLASSES OF EVAPORATING BINARIES AND THE POSSIBILITY OF EXTREME ABLATION TO PLANET PULSARS AND SINGLE MSP. COMPONENT MASS MEASUREMENTS ARE PARTICULARLY INTERESTING AS BLACK WIDOWS AND THEIR ILK MAY COMPRISE THE MOST MASSIVE NEUTRON STARS KNOWN. OUR PROGRAM CAN GREATLY REDUCE THE SYSTEMATIC UNCERTAINTY IN THE PULSAR MASS DETERMINATIONS BY COMBINING OBSERVABLES FROM THE SEVERAL WAVEBANDS; THE RESULTS MAY HAVE IMPORTANT IMPLICATIONS FOR OUR UNDERSTANDING OF THE EQUATION-OF-STATE OF MATTER AT SUPER-NUCLEAR DENSITIES. THE PROGRAM IS RESPONSIVE TO THE ADAP SECTION OF THE ROSES-16 SOLICITATION IN THAT IT SEEKS FUNDAMENTAL PROGRESS IN UNDERSTANDING AN IMPORTANT CLASS OF ASTROPHYSICAL SOURCES THROUGH MULTI-MISSION MULTI-WAVELENGTH ANALYSIS OF ARCHIVAL SPACE DATA SETS. DELIVERABLES INCLUDE A UNIFORM ASSESSMENT OF IBS EMISSION IN THE GALACTIC EVAPORATING PULSAR POPULATION MODELING CODES FOR THE DETERMINATION OF BINARY PARAMETERS AND EVALUATION OF THE CRITICAL OBSERVATIONS NEEDED TO ALLOW REFINED PROBES OF THE EVAPORATION PHYSICS.

$349,219FY2020National Aeronautics and Space AdministrationNASA

The Leland Stanford Junior University

Investigators

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