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SUMMARY:Measuring Geometric Distances Using Interferometry and Reverberati
 on Mapping of Broad-line Regions
DTSTART;VALUE=DATE-TIME:20261108T083000Z
DTEND;VALUE=DATE-TIME:20261108T090000Z
DTSTAMP;VALUE=DATE-TIME:20261023T133214Z
UID:indico-contribution-2967@indico.itp.ac.cn
DESCRIPTION:Speakers: Yan-Rong Li (Institute of High Energy Physics)\nThe 
 geometric distances of active galactic nuclei (AGNs) are challenging to me
 asure because of their exceptionally compact structure\, yet vast cosmic d
 istances. A combination of spectroastrometry and reverberation mapping (SA
 RM) of broad-line regions (BLRs) constitutes a novel means to probe the ge
 ometric distance of AGNs\, which has recently become practically feasible 
 owing to successful interferometric observations with the Very Large Teles
 cope Interferometer/GRAVITY. Here\, we perform SARM analysis of four nearb
 y quasars: Mrk 509\, PDS 456\, 3C 273\, and NGC 3783. Results for the form
 er two are reported for the first time\, and the latter two are revisited 
 using our improved BLR dynamical modeling that includes the radial-depende
 nt responsivity of BLRs. This allows us to self-consistently account for t
 he emissivity weighting of the BLR in spectroastrometry and responsivity w
 eighting in reverberation mapping. We obtain angular-diameter distances of
  the four quasars\, from which we derive a Hubble constant of H0=69(−10 
 +12)km/s/Mpc . Although this constitutes a large uncertainty for a measure
 ment of H0\, it is anticipated that the precision will improve to a compet
 itive level once a greater number of AGNs are accessible following the upg
 rade of GRAVITY in the near future.\n\nhttps://indico.itp.ac.cn/event/417/
 contributions/2967/
LOCATION:
URL:https://indico.itp.ac.cn/event/417/contributions/2967/
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