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THE X-RAY SPECTRA OF ACCRETING BLACK HOLES (BHS) SHOW A REFLECTION COMPONENT THAT IS FORMED WHEN HARD X-RAYS IRRADIATE THE DISK. THIS COMPONENT INCLUDES A FLUORESCENT IRON EMISSION LINE AN IRON ABSORPTION EDGE AND AN EXCESS AT TENS OF KEV WHICH IS OFTEN CALLED THE COMPTON HUMP. IF THE INNER EDGE OF THE DISK IS CLOSE TO THE BH RELATIVISTIC VELOCITIES OF THE DISK MATERIAL AND A REDSHIFT FROM THE BH'S GRAVITATIONAL FIELD DISTORT THE REFLECTION COMPONENT. THIS RELATIVISTIC DISTORTION ALLOWS FOR A DETERMINATION OF THE INNER RADIUS OF THE OPTICALLY THICK DISK WHICH OFTEN PROVIDES A CONSTRAINT ON THE BH SPIN. SUCH STUDIES HAVE BEEN USED TO CONSTRAIN SPINS FOR STELLAR MASS BHS AND ACTIVE GALACTIC NUCLEI (AGN). THE VAST MAJORITY OF PREVIOUS REFLECTION STUDIES HAVE USED CONSTANT DENSITY REFLECTION MODELS WHERE THE DENSITY IS SET WHEN THE MODEL IS CALCULATED AND IS NOT A FREE PARAMETER DURING THE SPECTRAL FITTING. ALSO MOST STUDIES OF STELLAR MASS BHS HAVE USED A DENSITY THAT IS APPROPRIATE FOR AGN ACCRETION DISKS EVEN THOUGH THE DISKS AROUND STELLAR MASS BHS ARE ESTIMATED TO BE ABOUT 1E6-1E7 TIMES HIGHER IN DENSITY. WHILE SUCH MODELS HAVE WORKED RELATIVELY WELL WHEN FITTING SPECTRA WITH LIMITED BANDPASS (E.G. 0.5-10 KEV) OR SPECTRA OF LOWER STATISTICAL QUALITY THERE ARE CASES WHERE POOR FITS OR APPARENTLY UNPHYSICAL PARAMETERS HAVE BEEN OBTAINED WHEN FITTING SPECTRA TAKEN BY THE NUSTAR SATELLITE WITH EXCELLENT QUALITY OVER THE 3-79 KEV BANDPASS. ONE EXAMPLE IS THAT A NUMBER OF SOURCES APPEAR TO SHOW EVIDENCE FOR EXTREME SUPERSOLAR IRON ABUNDANCES. IN ONE OF THE MOST EXTREME CASES AN INTERMEDIATE STATE OBSERVATION OF CYG X-1 STANDARD REFLECTION MODELS LEAD TO IRON ABUNDANCES CONSISTENT WITH 10 TIMES SOLAR. HOWEVER IF A HIGH-DENSITY MODEL IS USED THE SPECTRUM CAN BE FIT WITH SOLAR ABUNDANCES (TOMSICK ET AL. 2018 APJ 855 3). FOR THIS PROJECT WE PROPOSE TO ANALYZE ADDITIONAL ARCHIVAL DATA FROM CYG X-1 AS WELL AS FROM SIX OTHER ACCRETING BH SYSTEMS (23 DATA SETS IN TOTAL) IN ORDER TO TEST THE APPLICABILITY OF THE HIGH-DENSITY MODELS. NUSTAR SPECTRA WILL BE USED IN COMBINATION WITH SPECTRA FROM SOFT X-RAY SATELLITES (SUZAKU XMM-NEWTON OR THE NEIL GEHRELS SWIFT OBSERVATORY DEPENDING ON AVAILABILITY FOR THE DIFFERENT DATA SETS). WE WILL STUDY WHETHER THE HIGHER DENSITY MODELS LEAD TO OTHER CHANGES IN OUR PHYSICAL PICTURE OF ACCRETING BHS. IN PARTICULAR WE WILL INVESTIGATE THE BH SPIN THE GEOMETRY OF THE HARD X-RAY SOURCE THE INCLINATION OF THE INNER PART OF THE DISK AND THE INNER RADIUS OF THE DISK. BOTH BH SPIN AND INCLINATION PROVIDE INFORMATION ABOUT BH FORMATION AND THIS IS ESPECIALLY INTERESTING IN LIGHT OF THE GROWING EVIDENCE THAT THE BHS IN THE GRAVITATIONAL WAVE EVENTS MAY TYPICALLY HAVE LOW SPIN.

$253,940FY2020National Aeronautics and Space AdministrationNASA

Regents Of The University Of California, The

Investigators

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THE X-RAY SPECTRA OF ACCRETING BLACK HOLES (BHS) SHOW A REFLECTION COMPONENT THAT IS FORMED WHEN HARD X-RAYS IRRADIATE THE DISK. THIS COMPONENT INCLUDES A FLUORESCENT IRON EMISSION LINE AN IRON ABSORPTION EDGE AND AN EXCESS AT TENS OF KEV WHICH IS OFTEN CALLED THE COMPTON HUMP. IF THE INNER EDGE OF THE DISK IS CLOSE TO THE BH RELATIVISTIC VELOCITIES OF THE DISK MATERIAL AND A REDSHIFT FROM THE BH'S GRAVITATIONAL FIELD DISTORT THE REFLECTION COMPONENT. THIS RELATIVISTIC DISTORTION ALLOWS FOR A DETERMINATION OF THE INNER RADIUS OF THE OPTICALLY THICK DISK WHICH OFTEN PROVIDES A CONSTRAINT ON THE BH SPIN. SUCH STUDIES HAVE BEEN USED TO CONSTRAIN SPINS FOR STELLAR MASS BHS AND ACTIVE GALACTIC NUCLEI (AGN). THE VAST MAJORITY OF PREVIOUS REFLECTION STUDIES HAVE USED CONSTANT DENSITY REFLECTION MODELS WHERE THE DENSITY IS SET WHEN THE MODEL IS CALCULATED AND IS NOT A FREE PARAMETER DURING THE SPECTRAL FITTING. ALSO MOST STUDIES OF STELLAR MASS BHS HAVE USED A DENSITY THAT IS APPROPRIATE FOR AGN ACCRETION DISKS EVEN THOUGH THE DISKS AROUND STELLAR MASS BHS ARE ESTIMATED TO BE ABOUT 1E6-1E7 TIMES HIGHER IN DENSITY. WHILE SUCH MODELS HAVE WORKED RELATIVELY WELL WHEN FITTING SPECTRA WITH LIMITED BANDPASS (E.G. 0.5-10 KEV) OR SPECTRA OF LOWER STATISTICAL QUALITY THERE ARE CASES WHERE POOR FITS OR APPARENTLY UNPHYSICAL PARAMETERS HAVE BEEN OBTAINED WHEN FITTING SPECTRA TAKEN BY THE NUSTAR SATELLITE WITH EXCELLENT QUALITY OVER THE 3-79 KEV BANDPASS. ONE EXAMPLE IS THAT A NUMBER OF SOURCES APPEAR TO SHOW EVIDENCE FOR EXTREME SUPERSOLAR IRON ABUNDANCES. IN ONE OF THE MOST EXTREME CASES AN INTERMEDIATE STATE OBSERVATION OF CYG X-1 STANDARD REFLECTION MODELS LEAD TO IRON ABUNDANCES CONSISTENT WITH 10 TIMES SOLAR. HOWEVER IF A HIGH-DENSITY MODEL IS USED THE SPECTRUM CAN BE FIT WITH SOLAR ABUNDANCES (TOMSICK ET AL. 2018 APJ 855 3). FOR THIS PROJECT WE PROPOSE TO ANALYZE ADDITIONAL ARCHIVAL DATA FROM CYG X-1 AS WELL AS FROM SIX OTHER ACCRETING BH SYSTEMS (23 DATA SETS IN TOTAL) IN ORDER TO TEST THE APPLICABILITY OF THE HIGH-DENSITY MODELS. NUSTAR SPECTRA WILL BE USED IN COMBINATION WITH SPECTRA FROM SOFT X-RAY SATELLITES (SUZAKU XMM-NEWTON OR THE NEIL GEHRELS SWIFT OBSERVATORY DEPENDING ON AVAILABILITY FOR THE DIFFERENT DATA SETS). WE WILL STUDY WHETHER THE HIGHER DENSITY MODELS LEAD TO OTHER CHANGES IN OUR PHYSICAL PICTURE OF ACCRETING BHS. IN PARTICULAR WE WILL INVESTIGATE THE BH SPIN THE GEOMETRY OF THE HARD X-RAY SOURCE THE INCLINATION OF THE INNER PART OF THE DISK AND THE INNER RADIUS OF THE DISK. BOTH BH SPIN AND INCLINATION PROVIDE INFORMATION ABOUT BH FORMATION AND THIS IS ESPECIALLY INTERESTING IN LIGHT OF THE GROWING EVIDENCE THAT THE BHS IN THE GRAVITATIONAL WAVE EVENTS MAY TYPICALLY HAVE LOW SPIN. · GrantIndex