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SUMMARY:Time-domain axion searches with magnetic white dwarfs
DTSTART:20260713T121500Z
DTEND:20260713T141500Z
DTSTAMP:20260712T041600Z
UID:indico-event-1621@indico.hiskp.uni-bonn.de
DESCRIPTION:Speakers: Hong-Yi Zhang\n\nMagnetic white dwarfs can convert p
 hotons into axions in their strong magnetic fields\, with the conversion p
 robability modulating the light curve as the star rotates. However\, this 
 observable is degenerate with intrinsic stellar variability if the backgro
 und is modeled too simplistically. We develop a controlled background-dege
 neracy framework that computes the axion-induced modulation from reconstru
 cted stellar magnetic fields while fitting it simultaneously with a flexib
 le Fourier model of the intrinsic light curve. Applying this framework to 
 TESS observations of PG 1015+014 using two independent magnetic field reco
 nstructions\, we find that a sinusoidal stellar background can produce an 
 apparent preference for nonzero axion-photon conversion. This preference i
 s absorbed once the background light curve includes the second harmonic\, 
 indicating that higher-harmonic stellar variability is a leading degenerac
 y for precise photometric axion searches in magnetic white dwarfs. Interpr
 eting the two-harmonic fit as a conservative baseline\, we obtain stringen
 t constraints on the axion-photon coupling for sub-μeV axions. We furthe
 r derive an analytic target-ranking estimate for other TESS magnetic white
  dwarfs\, identifying systems where phase-resolved magnetic modeling would
  be most valuable for competitive axion probes.\n \n\nhttps://indico.hisk
 p.uni-bonn.de/event/1621/
URL:https://indico.hiskp.uni-bonn.de/event/1621/
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