A possible tension between galaxy rotational velocity and observed physical properties

Shamir, Lior; McAdam, Darius

doi:10.48550/arxiv.2212.04044

Cited by 3 publications

(6 citation statements)

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“…An interesting observation is that the most likely position of the dipole axis is at close proximity to the galactic pole, which might indicate that the dipole axis is not related to the large-scale structure of the local Universe but to internal structure of galaxies. That is discussed in (Shamir, 2022d(Shamir, , 2023a. able at https://people.cs.ksu.edu/ ~lshamir/ data/sparcfire/.…”

Section: Discussionmentioning

confidence: 99%

“…As discussed in (Shamir, 2020a(Shamir, , 2022d, the observed anisotropy in the distribution of galaxy spin directions might also be driven by internal structure of galaxies rather than the large-scale structure of the Universe. In that case, the rotational velocity of the Milky Way relative to the rotational velocity of the observed galaxies would exhibit parity violation, forming an axis that is expected to peak at around the Galactic pole (Shamir, 2020a(Shamir, , 2022d(Shamir, , 2023a(Shamir, , 2017. More information about the possible link between the anisotropy in galaxy spin directions and internal structure of galaxies is provided in (Shamir, 2022d).…”

Section: Introductionmentioning

confidence: 96%

“…In that case, the rotational velocity of the Milky Way relative to the rotational velocity of the observed galaxies would exhibit parity violation, forming an axis that is expected to peak at around the Galactic pole (Shamir, 2020a(Shamir, , 2022d(Shamir, , 2023a(Shamir, , 2017. More information about the possible link between the anisotropy in galaxy spin directions and internal structure of galaxies is provided in (Shamir, 2022d).…”

Section: Introductionmentioning

confidence: 99%

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Reanalysis of the spin direction distribution of Galaxy Zoo SDSS spiral galaxies

McAdam¹,

Shamir²

2023

Preprint

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The distribution of the spin directions of spiral galaxies in the Sloan Digital Sky Survey has been a topic of debate in the past two decades, with conflicting conclusions reported even in cases where the same data was used. Here we follow one of the previous experiments by applying the SpArcFiRe algorithm to annotate the spin directions in original dataset of Galaxy Zoo 1. The annotation of the galaxy spin directions is done after a first step of selecting the spiral galaxies in three different manners: manual analysis by Galaxy Zoo classifications, by a model-driven computer analysis, and with no selection of spiral galaxies. The results show that when spiral galaxies are selected by Galaxy Zoo volunteers, the distribution of their spin directions as determined by SpArcFiRe is not random, which agrees with previous reports. When selecting the spiral galaxies using a model-driven computer analysis or without selecting the spiral galaxies at all, the distribution is also not random. Simple binomial distribution analysis shows that the probability of the parity violation to occur by chance is lower than 0.01. Fitting the spin directions as observed from Earth to cosine dependence exhibits a dipole axis with statistical strength of 2.33σ to 3.97σ. These experiments show that regardless of the selection mechanism and the analysis method, all experiments show similar conclusions. These results are aligned with previous reports using other methods and telescopes, suggesting that the spin directions of spiral galaxies as observed from Earth exhibit a dipole axis formed by their spin directions. Possible explanations can be related to the large-scale structure of the Universe, or to internal structure of galaxies. The catalogs of annotated galaxies generated as part of this study are available.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Reanalysis of the spin direction distribution of Galaxy Zoo SDSS spiral galaxies

McAdam¹,

Shamir²

2023

Preprint

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“…The process by which the galaxies were sorted by their direction of rotation is explained in detail in [60] and is similar to the process of annotating galaxies imaged by other telescopes [61][62][63][64][65][66][67]. In summary, the annotation is conducted using the Ganalyzer algorithm [68], where each galaxy image is transformed into its radial intensity plot such that the value of the pixel at Cartesian coordinates (θ, r) in the radial intensity plot is the median value of the 5 × 5 pixels at coordinates (O x + sin(θ) • r, O y − cos(θ) • r) in the original galaxy image, where r is the radial distance measured in percentage of the galaxy radius, θ is the polar angle in degrees relative to the galaxy center, and (O x , O y ) is the coordinates of the galaxy center.…”

Section: Datamentioning

confidence: 99%

“…The direction of the curves of the arms is determined by the sign of the slope. Based on previous experiments [60,[62][63][64][65][66][67], to avoid incorrect annotations, a direction was determined only for galaxies that had at least 30 peaks and are identified in the radial intensity plot. If fewer than 30 peaks were identified, the galaxy was not used, as its direction of rotation cannot be identified.…”

Section: Datamentioning

confidence: 99%

A Simple Direct Empirical Observation of Systematic Bias of the Redshift as a Distance Indicator

Shamir

2024

Universe

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Recent puzzling observations, such as the H0 tension, large-scale anisotropies, and massive disk galaxies at high redshifts, have been challenging the standard cosmological model. While one possible explanation is that the standard model is incomplete, other theories are based on the contention that the redshift model as a distance indicator might be biased. These theories can explain the recent observations, but they are challenged by the absence of a direct empirical reproducible observation that the redshift model can indeed be inconsistent. Here, I describe a simple experiment that shows that the spectra of galaxies depend on their rotational velocity relative to the rotational velocity of the Milky Way. Moreover, it shows that the redshift of galaxies that rotate in the opposite direction relative to the Milky Way is significantly smaller compared with the redshift of galaxies that rotate in the same direction relative to the Milky Way (p < 0.006). Three different datasets were used independently, each one was prepared in a different manner, and all of them showed similar redshift bias. A fourth dataset of galaxies from the Southern Galactic pole was also analyzed and shows similar results. All four datasets are publicly available. While a maximum average z difference of ∼0.012 observed with galaxies of relatively low redshift (z < 0.25) is not extreme, the bias is consistent and canpotentially lead to explanations to puzzling observations such as the H0 tension.

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The many tensions with dark-matter based models and implications on the nature of the Universe

Kroupa,

Gjergo,

Asencio

et al. 2023

Proceedings of Corfu Summer Institute 2022 "School and Workshops on Elementary Particle Physics and Gravity" — PoS(CORFU2022)

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A possible tension between galaxy rotational velocity and observed physical properties

Cited by 3 publications

References 0 publications

Reanalysis of the spin direction distribution of Galaxy Zoo SDSS spiral galaxies

Reanalysis of the spin direction distribution of Galaxy Zoo SDSS spiral galaxies

A Simple Direct Empirical Observation of Systematic Bias of the Redshift as a Distance Indicator

The many tensions with dark-matter based models and implications on the nature of the Universe

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