TY - JOUR
T1 - Millisecond pulsars from accretion-induced collapse as the origin of the Galactic Centre gamma-ray excess signal
AU - Gautam, Anuj
AU - Crocker, Roland M.
AU - Ferrario, Lilia
AU - Ruiter, Ashley J.
AU - Ploeg, Harrison
AU - Gordon, Chris
AU - Macias, Oscar
N1 - Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Springer Nature Limited.
PY - 2022/6
Y1 - 2022/6
N2 - Gamma-ray data from the Fermi Large Area Telescope reveal an unexplained, apparently diffuse, signal from the Galactic bulge1–3 that peaks near ~2 GeV with an approximately spherical4 intensity profile ∝ r−2.4 (refs. 3,5), where r is the radial distance to the Galactic centre, that extends to angular radial scales of at least ~10° and possibly to ~20° (refs. 6,7). The origin of this ‘Galactic Centre excess’ (GCE) has been debated, with proposed sources prominently including self-annihilating dark matter1,4 and a hitherto undetected population of millisecond pulsars (MSPs)8. However, the conventional channel for the generation of MSPs has been found to predict too many low-mass X-ray binary (LMXB) systems9 and, because of the expected large natal kicks, may not accommodate10 the close spatial correspondence11–13 between the GCE signal and stars in the bulge. Here we report a binary population synthesis (BPS) forward model that demonstrates that an MSP population arising from the accretion-induced collapse (AIC) of O–Ne white dwarfs in Galactic bulge binaries can naturally reproduce the morphology, spectral shape and intensity of the GCE signal while also obeying LMXB constraints. Synchrotron emission from MSP-launched cosmic ray electrons and positrons may simultaneously explain the mysterious microwave ‘haze’14 from the inner Galaxy.
AB - Gamma-ray data from the Fermi Large Area Telescope reveal an unexplained, apparently diffuse, signal from the Galactic bulge1–3 that peaks near ~2 GeV with an approximately spherical4 intensity profile ∝ r−2.4 (refs. 3,5), where r is the radial distance to the Galactic centre, that extends to angular radial scales of at least ~10° and possibly to ~20° (refs. 6,7). The origin of this ‘Galactic Centre excess’ (GCE) has been debated, with proposed sources prominently including self-annihilating dark matter1,4 and a hitherto undetected population of millisecond pulsars (MSPs)8. However, the conventional channel for the generation of MSPs has been found to predict too many low-mass X-ray binary (LMXB) systems9 and, because of the expected large natal kicks, may not accommodate10 the close spatial correspondence11–13 between the GCE signal and stars in the bulge. Here we report a binary population synthesis (BPS) forward model that demonstrates that an MSP population arising from the accretion-induced collapse (AIC) of O–Ne white dwarfs in Galactic bulge binaries can naturally reproduce the morphology, spectral shape and intensity of the GCE signal while also obeying LMXB constraints. Synchrotron emission from MSP-launched cosmic ray electrons and positrons may simultaneously explain the mysterious microwave ‘haze’14 from the inner Galaxy.
UR - http://www.scopus.com/inward/record.url?scp=85128999023&partnerID=8YFLogxK
U2 - 10.1038/s41550-022-01658-3
DO - 10.1038/s41550-022-01658-3
M3 - Article
SN - 2397-3366
VL - 6
SP - 703
EP - 707
JO - Nature Astronomy
JF - Nature Astronomy
IS - 6
ER -