Directional dependence of CMB parity asymmetry

Zhao, Wen

doi:10.1103/physrevd.89.023010

Cited by 39 publications

(56 citation statements)

References 32 publications

(61 reference statements)

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“…Another anomaly observed in Planck maps that breaks the expected statistical isotropy is an apparent parity asymmetry: there is more power in the odd multipoles than in the even multipoles (Akrami et al 2019). It has been suggested by Naselsky et al (2012) and Zhao (2014) that the odd-multipole preference of the CMB power spectrum could be induced by the kinematic dipole. In this section, using simulations we examine whether the motion of the observer can cause a parity asymmetry in the CMB temperature and polarization maps.…”

Section: Parity Asymmetrymentioning

confidence: 99%

Footprints of Doppler and aberration effects in cosmic microwave background experiments: statistical and cosmological implications

Yasini

Pierpaoli

2020

Monthly Notices of the Royal Astronomical Society

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In the frame of the Solar System, the Doppler and aberration effects cause distortions in the form of mode couplings in the cosmic microwave background (CMB) temperature and polarization power spectra and hence impose biases on the statistics derived by the moving observer. We explore several aspects of such biases and pay close attention to their effects on CMB polarization which previously have not been examined in detail. A potentially important bias that we introduce here is boost variancean additional term in cosmic variance, induced by the observer's motion. Although this additional term is negligible for whole-sky experiments, in partial-sky experiments it can reach 10% (temperature) -20% (polarization) of the standard cosmic variance (σ). Furthermore, we investigate the significance of motion-induced power and parity asymmetries in TT, EE, and TE as well as potential biases induced in cosmological parameter estimation performed with whole-sky TTTEEE. Using Planck-like simulations, we find that our local motion induces ∼ 1 − 2% hemispherical asymmetry in a wide range of angular scales in the CMB temperature and polarization power spectra; however, it does not imply any significant amount of parity asymmetry or shift in cosmological parameters. Finally, we examine the prospects of measuring the velocity of the Solar System w.r.t. the CMB with future experiments via the mode coupling induced by the Doppler and aberration effects. Using the CMB TT, EE, and TE power spectra up to = 4000, SO and CMB-S4 can make a dipole-independent measurement of our local velocity respectively at 8.5σ and 20σ.

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Section: Parity Asymmetrymentioning

confidence: 99%

Footprints of Doppler and aberration effects in cosmic microwave background experiments: statistical and cosmological implications

Yasini

Pierpaoli

2020

Monthly Notices of the Royal Astronomical Society

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“…However, the cosmological principle has been challenged by a lot of accurate observations. An incomplete list includes the hemispherical power asymmetry of CMB temperature anisotropies (Eriksen et al 2004;Hansen et al 2004;Bennett et al 2013;Akrami et al 2014;Ade et al 2014;Quartin & Notari 2015), the alignment of low-multipoles in the CMB temperature anisotropies (Lineweaver et al 1996;Tegmark et al 2003;Bielewicz et al 2004;Frommert & Enlin 2010;Copi et al 2010), the parity asymmetry of low-Email: zhouyong@ihep.ac.cn multipoles in angular power spectrum of CMB temperature anisotropies (Kim & Naselsky 2010a,b, 2011Gruppuso et al 2011;Zhao 2014), the large-scale alignment of quasar polarization vector (Hutsemekers & Lamy 2001;Hutsemekers et al 2005). In addition, the spatial variation of finestructure constant (Webb et al 2011;King et al 2012;Mariano & Perivolaropoulos 2012;Molaro et al 2013) and MOND acceleration scale (Zhou et al 2017;Chang et al 2018b;Chang & Zhou 2019) are inconsistent with isotropic universe.…”

Section: Introductionmentioning

confidence: 99%

Anisotropy of the Universe via the Pantheon supernovae sample revisited

Zhao

Zhou

Chang

2019

Monthly Notices of the Royal Astronomical Society

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We employ the hemisphere comparison (HC) method and the dipole fitting (DF) method to investigate the cosmic anisotropy in the recently released Pantheon sample of type Ia supernovae (SNe Ia) and five combinations among Pantheon. For the HC method, we find the maximum anisotropy level in the full Pantheon sample is AL max = 0.361 ± 0.070 and corresponding direction (l, b) = (123.05A robust check shows the statistical significance of maximum anisotropy level is about 2.1σ. We also find that the Low-z and SNLS subsamples have decisive impact on the overall anisotropy while other three subsamples have little impact. Moreover, the anisotropy level map significantly rely on the inhomogeneous distribution of SNe Ia in the sky. For the DF method, we find the dipole anisotropy in the Pantheon sample is very weak. The dipole magnitude is constrained to be less than 1.16 × 10 −3 at 95% confidence level. However, the dipole direction is well inferred by MCMC method and it points towards (l, b) = (306.00 •+82.95 • −125.01 • , −34.20 •+16.82 • −54.93 • ). This direction is very close to the axial direction to the plane of SDSS subsample. It may imply that SDSS subsample is the decisive part to the dipole anisotropy in the full Pantheon sample. All these facts imply that the cosmic anisotropy found in Pantheon sample significantly rely on the inhomogeneous distribution of SNe Ia in the sky. More homogeneous distribution of SNe Ia is necessary to search for a more convincing cosmic anisotropy.

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“…On the other hand, it is several degrees far away from the directions of the intrinsic CMB and the Dark Flow dipoles, from the kinetic CMB asymmetry, and from the CMB cold spot location [11][12][13][14][15][16][17][18][19][20][21][22][23]. Studies that specifically look for a dipole modulation of the α anisotropies on the Cosmic Microwave * ivan.demartino1983@gmail.com † Carlos.Martins@astro.up.pt ‡ ebeling@ifa.hawaii.edu § dale.kocevski@colby.edu…”

Section: Introductionmentioning

confidence: 99%

Constraining spatial variations of the fine structure constant using clusters of galaxies and Planck data

et al. 2016

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We propose an improved methodology to constrain spatial variations of the fine structure constant using clusters of galaxies. We use the Planck 2013 data to measure the thermal Sunyaev-Zeldovich effect at the location of 618 X-ray selected clusters. We then use a Monte Carlo Markov Chain algorithm to obtain the temperature of the Cosmic Microwave Background at the location of each galaxy cluster. When fitting three different phenomenological parameterizations allowing for monopole and dipole amplitudes in the value of the fine structure constant we improve the results of earlier analysis involving clusters and the CMB power spectrum, and we also found that the best-fit direction of a hypothetical dipole is compatible with the direction of other known anomalies. Although the constraining power of our current datasets do not allow us to test the indications of a fine-structure constant dipole obtained though high-resolution optical/UV spectroscopy, our results do highlight that clusters of galaxies will be a very powerful tool to probe fundamental physics at low redshift.

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Directional dependence of CMB parity asymmetry

Cited by 39 publications

References 32 publications

Footprints of Doppler and aberration effects in cosmic microwave background experiments: statistical and cosmological implications

Footprints of Doppler and aberration effects in cosmic microwave background experiments: statistical and cosmological implications

Anisotropy of the Universe via the Pantheon supernovae sample revisited

Constraining spatial variations of the fine structure constant using clusters of galaxies and Planck data

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