Searches for large-scale anisotropies of cosmic rays: Harmonic analysis and shuffling technique

Deligny, O.; Salamida, F.

doi:10.1016/j.astropartphys.2013.05.003

Cited by 7 publications

(5 citation statements)

References 12 publications

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“…In addition to the CMB, probes that show anisotropy include radio sources [144][145][146][147][148], LX-T scaling [149], short gamma ray bursts [150], acceleration rates [151][152][153], Ia supernova [118,154], distribution of galaxy morphology types [155], dark energy [151,[156][157][158], fine structure constant [159], galaxy motion [160], H o [161], polarization of quasars [162][163][164][165][166], and cosmic rays [167][168][169][170]. It has also been shown that the large-scale distribution of galaxies in the Universe is not random [171], and it could have a preferred direction [66,71,73,77,[172][173][174][175][176][177].…”

Section: Large-scale Structure Explanationmentioning

confidence: 99%

Asymmetry between Galaxy Apparent Magnitudes Shows a Possible Tension between Physical Properties of Galaxies and Their Rotational Velocity

McAdam

Shamir

2023

Symmetry

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Despite over a century of research, the physics of galaxy rotation is not yet fully understood, and there is a clear discrepancy between the observed mass of galaxies and their rotational velocity. Here, we report on another observation of tension between the physical properties of galaxies and their rotational velocity. We compare the apparent magnitude of galaxies and find a statistically significant asymmetry between galaxies that rotate in the same direction relative to the Milky Way and galaxies that rotate in the opposite direction relative to the Milky Way. While asymmetry in the brightness is expected due to the Doppler shift effect, such asymmetry is expected to be subtle. The observations shown here suggest that the magnitude difference is sufficiently large to be detected by Earth-based telescopes. The asymmetry is consistent in both the northern and southern galactic poles. The difference is also consistent across several different instruments such as DECam, SDSS, Pan-STARRS, and HST as well as different annotation methods, which include automatic, manual, or crowdsourcing annotations through “Galaxy Zoo”. The observation can also explain other anomalies such as the Ho tension. Analysis of Ia supernovae where the host galaxies rotate in the same direction relative to the Milky Way shows a much smaller tension with the Ho value as estimated by the CMB.

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Section: Large-scale Structure Explanationmentioning

confidence: 99%

Asymmetry between Galaxy Apparent Magnitudes Shows a Possible Tension between Physical Properties of Galaxies and Their Rotational Velocity

McAdam

Shamir

2023

Symmetry

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“…dx , d y , and d z considering the effect of the limited exposure(Deligny & Salamida 2013; see also K-inverse method explained inDing et al 2019). The dipole components d e,iä(x,y,z) for each of the three energy bins are then compared to the measured…”

mentioning

confidence: 99%

Constraints on UHECR Sources and Extragalactic Magnetic Fields from Directional Anisotropies

Bister,

Farrar

2024

ApJ

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A dipole anisotropy in ultra–high-energy cosmic ray (UHECR) arrival directions, of extragalactic origin, is now firmly established at energies E > 8 EeV. Furthermore, the UHECR angular power spectrum shows no power at smaller angular scales than the dipole, apart from hints of possible individual hot or warm spots for energy thresholds ≳40 EeV. Here we exploit the magnitude of the dipole and the limits on smaller-scale anisotropies to place constraints on two quantities: the extragalactic magnetic field (EGMF) and the number density of UHECR sources or the volumetric event rate if UHECR sources are transient. We also vary the bias between the extragalactic matter and the UHECR source densities, reflecting whether UHECR sources are preferentially found in over- or underdense regions, and find that little or no bias is favored. We follow Ding et al. (2021) in using the CosmicFlows-2 density distribution of the local universe as our baseline distribution of UHECR sources, but we improve and extend that work by employing an accurate and self-consistent treatment of interactions and energy losses during propagation. Deflections in the Galactic magnetic field are treated using either the full JF12 magnetic field model, with both random and coherent components, or just the coherent part, to bracket the impact of the GMF on the dipole anisotropy. This large-scale structure model gives good agreement with both the direction and magnitude of the measured dipole anisotropy and forms the basis for simulations of discrete sources and the inclusion of EGMF effects.

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“…with Ñ = i 1/ω r (α i ). The uncertainty on the recovered coefficients then reads, still in the case of small anisotropies [40], as…”

Section: Harmonic Analysis In Right Ascensionmentioning

confidence: 99%

Measurement of Anisotropy and Search for UHECR Sources

Deligny,

Kawata,

Tinyakov

2017

Preprint

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Ultra-high energy cosmic rays (UHECRs) are particles, likely protons and/or nuclei, with energies up to 10 20 eV that are observed through the giant air showers they produce in the atmosphere. These particles carry the information on the most extreme phenomena in the Universe. At these energies, even charged particles could be magnetically rigid enough to keep track of, or even point directly to, the original positions of their sources on the sky. The discovery of anisotropy of UHECRs would thus signify opening of an entirely new window onto the Universe. With the construction and operation of the new generation of cosmic ray experiments -the Pierre Auger Observatory in the Southern hemisphere and the Telescope Array in the Northern one -the study of these particles, the most energetic ever detected, has experienced a jump in statistics as well as in the data quality, allowing for a much better sensitivity in searching for their sources. In this review, we summarize the searches for anisotropies and the efforts to identify the sources of UHECRs which have been carried out using these new data.

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Searches for large-scale anisotropies of cosmic rays: Harmonic analysis and shuffling technique

Cited by 7 publications

References 12 publications

Asymmetry between Galaxy Apparent Magnitudes Shows a Possible Tension between Physical Properties of Galaxies and Their Rotational Velocity

Asymmetry between Galaxy Apparent Magnitudes Shows a Possible Tension between Physical Properties of Galaxies and Their Rotational Velocity

Constraints on UHECR Sources and Extragalactic Magnetic Fields from Directional Anisotropies

Measurement of Anisotropy and Search for UHECR Sources

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