Search for CP violating signature of intergalactic magnetic helicity in the gamma-ray sky

Hiroyuki Tashiro, Wenlei Chen, Francesc Ferrer, Tanmay Vachaspati

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

The existence of a cosmological magnetic field could be revealed by the effects of non-trivial helicity on large scales. We evaluate a CP (conjugation plus parity) odd statistic, Q, using gamma-ray data obtained from Fermi satellite observations at high galactic latitudes to search for such a signature. Observed values of Q are found to be non-zero; the probability of a similar signal in Monte Carlo simulations is ~0.2 per cent. Contamination from the Milky Way does not seem to be responsible for the signal since it is present even for data at very high galactic latitudes. Assuming that the signal is indeed due to a helical cosmological magnetic field, our results indicate left-handed magnetic helicity and field strength ~10<sup>-14</sup> G on ~10 Mpc scales.

Original languageEnglish (US)
Pages (from-to)L41-L45
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume445
Issue number1
DOIs
StatePublished - 2014

Fingerprint

conjugation
sky
parity
signatures
gamma rays
magnetic field
satellite observation
magnetic fields
field strength
contamination
statistics
simulation

Keywords

  • Cosmology: observations
  • Early universe
  • Gamma-rays: diffuse background

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Search for CP violating signature of intergalactic magnetic helicity in the gamma-ray sky. / Tashiro, Hiroyuki; Chen, Wenlei; Ferrer, Francesc; Vachaspati, Tanmay.

In: Monthly Notices of the Royal Astronomical Society: Letters, Vol. 445, No. 1, 2014, p. L41-L45.

Research output: Contribution to journalArticle

@article{13f42bea80f04c429c0975908f72ce8a,
title = "Search for CP violating signature of intergalactic magnetic helicity in the gamma-ray sky",
abstract = "The existence of a cosmological magnetic field could be revealed by the effects of non-trivial helicity on large scales. We evaluate a CP (conjugation plus parity) odd statistic, Q, using gamma-ray data obtained from Fermi satellite observations at high galactic latitudes to search for such a signature. Observed values of Q are found to be non-zero; the probability of a similar signal in Monte Carlo simulations is ~0.2 per cent. Contamination from the Milky Way does not seem to be responsible for the signal since it is present even for data at very high galactic latitudes. Assuming that the signal is indeed due to a helical cosmological magnetic field, our results indicate left-handed magnetic helicity and field strength ~10-14 G on ~10 Mpc scales.",
keywords = "Cosmology: observations, Early universe, Gamma-rays: diffuse background",
author = "Hiroyuki Tashiro and Wenlei Chen and Francesc Ferrer and Tanmay Vachaspati",
year = "2014",
doi = "10.1093/mnrasl/slu134",
language = "English (US)",
volume = "445",
pages = "L41--L45",
journal = "Monthly Notices of the Royal Astronomical Society: Letters",
issn = "1745-3933",
publisher = "Oxford University Press",
number = "1",

}

TY - JOUR

T1 - Search for CP violating signature of intergalactic magnetic helicity in the gamma-ray sky

AU - Tashiro, Hiroyuki

AU - Chen, Wenlei

AU - Ferrer, Francesc

AU - Vachaspati, Tanmay

PY - 2014

Y1 - 2014

N2 - The existence of a cosmological magnetic field could be revealed by the effects of non-trivial helicity on large scales. We evaluate a CP (conjugation plus parity) odd statistic, Q, using gamma-ray data obtained from Fermi satellite observations at high galactic latitudes to search for such a signature. Observed values of Q are found to be non-zero; the probability of a similar signal in Monte Carlo simulations is ~0.2 per cent. Contamination from the Milky Way does not seem to be responsible for the signal since it is present even for data at very high galactic latitudes. Assuming that the signal is indeed due to a helical cosmological magnetic field, our results indicate left-handed magnetic helicity and field strength ~10-14 G on ~10 Mpc scales.

AB - The existence of a cosmological magnetic field could be revealed by the effects of non-trivial helicity on large scales. We evaluate a CP (conjugation plus parity) odd statistic, Q, using gamma-ray data obtained from Fermi satellite observations at high galactic latitudes to search for such a signature. Observed values of Q are found to be non-zero; the probability of a similar signal in Monte Carlo simulations is ~0.2 per cent. Contamination from the Milky Way does not seem to be responsible for the signal since it is present even for data at very high galactic latitudes. Assuming that the signal is indeed due to a helical cosmological magnetic field, our results indicate left-handed magnetic helicity and field strength ~10-14 G on ~10 Mpc scales.

KW - Cosmology: observations

KW - Early universe

KW - Gamma-rays: diffuse background

UR - http://www.scopus.com/inward/record.url?scp=84922546731&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84922546731&partnerID=8YFLogxK

U2 - 10.1093/mnrasl/slu134

DO - 10.1093/mnrasl/slu134

M3 - Article

AN - SCOPUS:84922546731

VL - 445

SP - L41-L45

JO - Monthly Notices of the Royal Astronomical Society: Letters

JF - Monthly Notices of the Royal Astronomical Society: Letters

SN - 1745-3933

IS - 1

ER -