Axion Emission Can Explain a New Hard X-Ray Excess from Nearby Isolated Neutron Stars

Malte Buschmann; Raymond T. Co; Christopher Dessert; Benjamin R. Safdi

doi:10.1103/PhysRevLett.126.021102

Axion Emission Can Explain a New Hard X-Ray Excess from Nearby Isolated Neutron Stars

Malte Buschmann
, Raymond T. Co
, Christopher Dessert
, Benjamin R. Safdi

Physics and Astronomy (Twin Cities)

Research output: Contribution to journal › Article › peer-review

57 Scopus citations

Abstract

Axions may be produced thermally inside the cores of neutron stars (NSs), escape the stars due to their feeble interactions with matter, and subsequently convert into x rays in the magnetic fields surrounding the stars. We show that a recently discovered excess of hard x-ray emission in the 2-8 keV energy range from the nearby magnificent seven isolated NSs could be explained by this emission mechanism. These NSs are unique in that they had previously been expected to only produce observable flux in the UV and soft x-ray bands from thermal surface emission at temperatures ∼100 eV. No conventional astrophysical explanation of the magnificent seven hard x-ray excess exists at present. We show that the hard x-ray excess may be consistently explained by an axionlike particle with mass ma∼2×10-5 eV and gaγγ×gann∈(2×10-21,10-18) GeV-1 at 95% confidence, accounting for both statistical and theoretical uncertainties, where gaγγ (gann) is the axion-photon (axion-neutron) coupling constant.

Original language	English (US)
Article number	021102
Journal	Physical review letters
Volume	126
Issue number	2
DOIs	https://doi.org/10.1103/PhysRevLett.126.021102
State	Published - Jan 12 2021

Bibliographical note

Funding Information:
We are grateful to Y. Kahn for collaboration in the early stages of this work and comments on the manuscript and to J. Foster, M. Reynolds, O. Gnedin, H. Günther, D. Hooper, A. Long, A. Ringwald, and D. Yakovlev for useful discussions and comments. We thank the anonymous referees for useful suggestions. This work was supported in part by the DOE Early Career Grant No. DE-SC0019225 and the DOE grant DE-SC0011842 (R. C.) at the University of Minnesota and through computational resources and services provided by Advanced Research Computing at the University of Michigan, Ann Arbor. C. D. was partially supported by the Leinweber Graduate Fellowship at the University of Michigan, Ann Arbor. This work was performed in part at the Aspen Center for Physics, which is supported by the National Science Foundation Grant No. PHY-1607611, and in part at the Mainz Institute for Theoretical Physics (MITP) of the Cluster of Excellence PRISMA+ (Project ID 39083149). We also acknowledge the Munich Institute for Astro- and Particle Physics (MIAPP) of the DFG Excellence Cluster Origins along with the CERN Theory department for hospitality during the completion of this work.

Publisher Copyright:
© 2021 authors.

PubMed: MeSH publication types

Journal Article

Publisher link

10.1103/PhysRevLett.126.021102

Find It

Find It at U of M Libraries

Cite this

@article{247074cc126243febf48da8a6d72b8ad,

title = "Axion Emission Can Explain a New Hard X-Ray Excess from Nearby Isolated Neutron Stars",

abstract = "Axions may be produced thermally inside the cores of neutron stars (NSs), escape the stars due to their feeble interactions with matter, and subsequently convert into x rays in the magnetic fields surrounding the stars. We show that a recently discovered excess of hard x-ray emission in the 2-8 keV energy range from the nearby magnificent seven isolated NSs could be explained by this emission mechanism. These NSs are unique in that they had previously been expected to only produce observable flux in the UV and soft x-ray bands from thermal surface emission at temperatures ∼100 eV. No conventional astrophysical explanation of the magnificent seven hard x-ray excess exists at present. We show that the hard x-ray excess may be consistently explained by an axionlike particle with mass ma∼2×10-5 eV and gaγγ×gann∈(2×10-21,10-18) GeV-1 at 95\% confidence, accounting for both statistical and theoretical uncertainties, where gaγγ (gann) is the axion-photon (axion-neutron) coupling constant.",

author = "Malte Buschmann and Co, \{Raymond T.\} and Christopher Dessert and Safdi, \{Benjamin R.\}",

note = "Funding Information: We are grateful to Y. Kahn for collaboration in the early stages of this work and comments on the manuscript and to J. Foster, M. Reynolds, O. Gnedin, H. G{\"u}nther, D. Hooper, A. Long, A. Ringwald, and D. Yakovlev for useful discussions and comments. We thank the anonymous referees for useful suggestions. This work was supported in part by the DOE Early Career Grant No. DE-SC0019225 and the DOE grant DE-SC0011842 (R. C.) at the University of Minnesota and through computational resources and services provided by Advanced Research Computing at the University of Michigan, Ann Arbor. C. D. was partially supported by the Leinweber Graduate Fellowship at the University of Michigan, Ann Arbor. This work was performed in part at the Aspen Center for Physics, which is supported by the National Science Foundation Grant No. PHY-1607611, and in part at the Mainz Institute for Theoretical Physics (MITP) of the Cluster of Excellence PRISMA+ (Project ID 39083149). We also acknowledge the Munich Institute for Astro- and Particle Physics (MIAPP) of the DFG Excellence Cluster Origins along with the CERN Theory department for hospitality during the completion of this work. Publisher Copyright: {\textcopyright} 2021 authors.",

year = "2021",

month = jan,

day = "12",

doi = "10.1103/PhysRevLett.126.021102",

language = "English (US)",

volume = "126",

journal = "Physical review letters",

issn = "0031-9007",

publisher = "American Physical Society",

number = "2",

}

TY - JOUR

T1 - Axion Emission Can Explain a New Hard X-Ray Excess from Nearby Isolated Neutron Stars

AU - Buschmann, Malte

AU - Co, Raymond T.

AU - Dessert, Christopher

AU - Safdi, Benjamin R.

N1 - Funding Information: We are grateful to Y. Kahn for collaboration in the early stages of this work and comments on the manuscript and to J. Foster, M. Reynolds, O. Gnedin, H. Günther, D. Hooper, A. Long, A. Ringwald, and D. Yakovlev for useful discussions and comments. We thank the anonymous referees for useful suggestions. This work was supported in part by the DOE Early Career Grant No. DE-SC0019225 and the DOE grant DE-SC0011842 (R. C.) at the University of Minnesota and through computational resources and services provided by Advanced Research Computing at the University of Michigan, Ann Arbor. C. D. was partially supported by the Leinweber Graduate Fellowship at the University of Michigan, Ann Arbor. This work was performed in part at the Aspen Center for Physics, which is supported by the National Science Foundation Grant No. PHY-1607611, and in part at the Mainz Institute for Theoretical Physics (MITP) of the Cluster of Excellence PRISMA+ (Project ID 39083149). We also acknowledge the Munich Institute for Astro- and Particle Physics (MIAPP) of the DFG Excellence Cluster Origins along with the CERN Theory department for hospitality during the completion of this work. Publisher Copyright: © 2021 authors.

PY - 2021/1/12

Y1 - 2021/1/12

N2 - Axions may be produced thermally inside the cores of neutron stars (NSs), escape the stars due to their feeble interactions with matter, and subsequently convert into x rays in the magnetic fields surrounding the stars. We show that a recently discovered excess of hard x-ray emission in the 2-8 keV energy range from the nearby magnificent seven isolated NSs could be explained by this emission mechanism. These NSs are unique in that they had previously been expected to only produce observable flux in the UV and soft x-ray bands from thermal surface emission at temperatures ∼100 eV. No conventional astrophysical explanation of the magnificent seven hard x-ray excess exists at present. We show that the hard x-ray excess may be consistently explained by an axionlike particle with mass ma∼2×10-5 eV and gaγγ×gann∈(2×10-21,10-18) GeV-1 at 95% confidence, accounting for both statistical and theoretical uncertainties, where gaγγ (gann) is the axion-photon (axion-neutron) coupling constant.

AB - Axions may be produced thermally inside the cores of neutron stars (NSs), escape the stars due to their feeble interactions with matter, and subsequently convert into x rays in the magnetic fields surrounding the stars. We show that a recently discovered excess of hard x-ray emission in the 2-8 keV energy range from the nearby magnificent seven isolated NSs could be explained by this emission mechanism. These NSs are unique in that they had previously been expected to only produce observable flux in the UV and soft x-ray bands from thermal surface emission at temperatures ∼100 eV. No conventional astrophysical explanation of the magnificent seven hard x-ray excess exists at present. We show that the hard x-ray excess may be consistently explained by an axionlike particle with mass ma∼2×10-5 eV and gaγγ×gann∈(2×10-21,10-18) GeV-1 at 95% confidence, accounting for both statistical and theoretical uncertainties, where gaγγ (gann) is the axion-photon (axion-neutron) coupling constant.

UR - https://www.scopus.com/pages/publications/85099625879

UR - https://www.scopus.com/pages/publications/85099625879#tab=citedBy

U2 - 10.1103/PhysRevLett.126.021102

DO - 10.1103/PhysRevLett.126.021102

M3 - Article

C2 - 33512228

AN - SCOPUS:85099625879

SN - 0031-9007

VL - 126

JO - Physical review letters

JF - Physical review letters

IS - 2

M1 - 021102

ER -

Axion Emission Can Explain a New Hard X-Ray Excess from Nearby Isolated Neutron Stars

Abstract

Bibliographical note

PubMed: MeSH publication types

Publisher link

Find It

Other files and links

Fingerprint

Cite this