Large-scale clustering amongst <i>Fermi</i> blazars; evidence for axis alignments?

Marchã, M. J. M.; Browne, I. W. A.

doi:10.1093/mnras/stab1872

Cited by 12 publications

(8 citation statements)

References 51 publications

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“…Radio galaxies also showed consistency in their angular momentum (Taylor and Jagannathan 2016), showing large-scale alignment agreement between surveys such as the Faint Images of the Radio Sky at Twenty-centimetres (FIRST) and the TIFR GMRT Sky Survey (TGSS) (Contigiani et al 2017;Panwar et al 2020). Large-scale clustering of Fermi blazars also showed a possible axis alignment (Marcha and Browne 2021). In addition to observational studies, numerical simulations also showed links between the large-scale structure and spin directions (Hahn et al 2007;Zhang et al 2009;Codis et al 2012;Trowland 2013;Libeskind et al 2013Libeskind et al , 2014Forero-Romero et al 2014;López et al 2019).…”

Section: Discussionmentioning

confidence: 55%

Analysis of spin directions of galaxies in the DESI Legacy Survey

Shamir

2022

Monthly Notices of the Royal Astronomical Society

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The DESI Legacy Survey is a digital sky survey with a large footprint compared to other Earth-based surveys, covering both the Northern and Southern hemispheres. This paper shows the distribution of the spin directions of spiral galaxies imaged by DESI Legacy Survey. A simple analysis of dividing nearly 1.3· 106 spiral galaxies into two hemispheres shows a higher number of galaxies spinning counterclockwise in the Northern hemisphere, and a higher number of galaxies spinning clockwise in the Southern hemisphere. That distribution is consistent with previous observations, but uses a far larger number of galaxies and a larger footprint. The larger footprint allows a comprehensive analysis without the need to fit the distribution into an a priori model, making this study different from all previous analyses of this kind. Fitting the spin directions of the galaxies to cosine dependence shows a dipole axis alignment with probability of P < 10−5. The analysis is done with a trivial selection of the galaxies, as well as simple explainable annotation algorithm that does not make use of any form of machine learning, deep learning, or pattern recognition. While further work will be required, these results are aligned with previous studies suggesting the possibility of a large-scale alignment of galaxy angular momentum.

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Section: Discussionmentioning

confidence: 55%

Analysis of spin directions of galaxies in the DESI Legacy Survey

Shamir

2022

Monthly Notices of the Royal Astronomical Society

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“…On the other hand, a large number of studies using numerous different probes show cosmological-scale isotropy and parity violations, suggesting that the Cosmological Principle might not be aligned with observations (Aluri et al, 2023). In addition to the cosmic microwave background radiation (Lue et al, 1999;Eriksen et al, 2004;Abramo et al, 2006;Cline et al, 2003;Gordon and Hu, 2004;Land and Magueijo, 2005;Campanelli et al, 2007;Mariano and Perivolaropoulos, 2013;Ade et al, 2014;Zhe et al, 2015;Santos et al, 2015;Dong et al, 2015;Gruppuso et al, 2018;Ashtekar et al, 2021;Luongo et al, 2022;Yeung and Chu, 2022), such probes also include dark energy (Adhav et al, 2011;Adhav, 2011;Perivolaropoulos, 2014; Colin * lshamir@mtu.edu et al, 2019), H o anisotropy (Luongo et al, 2021;Dainotti et al, 2022), distribution of galaxy morphology types (Javanmardi and Kroupa, 2017), cosmic rays (Aab et al, 2017), quasars (Hutsemékers et al, 2014;Slagter, 2022;Secrest et al, 2020;Zhao and Xia, 2021;Secrest et al, 2021), LX-T scaling (Migkas et al, 2020), Ia supernova (Javanmardi et al, 2015;Lin et al, 2016), short gamma ray bursts (Mészáros, 2019), large-scale clustering of Fermi blazars (Marcha and Browne, 2021), radio galaxies…”

Section: Introductionmentioning

confidence: 78%

Using 3D and 2D analysis for analyzing large-scale asymmetry in galaxy spin directions

Shamir

2022

Publications of the Astronomical Society of Japan

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The nature of galaxy spin is still not fully known. Iye, Yagi, and Fukumoto (2021, AJ, 907, 123) applied a 3D analysis to a dataset of bright SDSS galaxies that was used in the past for photometric analysis. They showed that the distribution of spin directions of spiral galaxies is random, providing a dipole axis with low statistical significance of 0.29σ. However, to show random distribution, two decisions were made, each of which can lead to random distribution regardless of the real distribution of the spin direction of galaxies. The first decision was to limit the dataset arbitrarily to z < 0.1, which is a redshift range in which previous literature already showed that random distribution is expected. More importantly, while the 3D analysis requires the redshift of each galaxy, the analysis was done with the photometric redshift. If the asymmetry existed, its signal is expected to be an order of magnitude weaker than the error of the photometric redshift, and therefore a low statistical signal under these conditions is expected. When using the exact same data without limiting to zphot < 0.1 and without using the photometric redshift, the distribution of the spin directions in that dataset shows a statistical signal of >2σ. Code and data for reproducing the analysis are publicly available. These results are in agreement with other experiments with SDSS, Pan-STARRS, HST, and the DESI Legacy Survey. The paper also examines other previous studies that showed random distribution in galaxy spin directions. While further research will be required, the current evidence suggests that large-scale asymmetry between the number of clockwise and counterclockwise galaxies cannot be ruled out.

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“…1 See also: Christian (2020) 2 See also: Nadathur (2013); Marinello et al (2016); Hutsemékers et al (2014) 3 See also : Marchã & Browne (2021) (rest equivalent widths 𝑊 𝑟 ,2796 , 𝑊 𝑟 ,2803 ) arising in the haloes corresponds to the properties of the galaxy and galaxy clusters, although there is still uncertainty about the relative importance of morphology, luminosity, impact parameter, galaxy inclination etc., and combinations of these, that lead to the different classes (weak, strong) of absorbers. See for example: Lanzetta & Bowen (1990); Churchill et al (2000); Steidel et al (2002); Churchill et al (2005); Chen et al (2010); Bordoloi et al (2011).…”

Section: The Mg II Approachmentioning

confidence: 99%

A Giant Arc on the Sky

Lopez

Clowes

Williger

2022

Monthly Notices of the Royal Astronomical Society

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We present the serendipitous discovery of a ‘Giant Arc on the Sky’ at z ∼ 0.8. The Giant Arc (GA) spans ∼1 Gpc (proper size, present epoch), and appears to be almost symmetrical on the sky. It was discovered via intervening Mg ii absorbers in the spectra of background quasars, using the catalogues of Zhu & Ménard. The use of Mg ii absorbers represents a new approach to the investigation of large-scale structures (LSSs) at redshifts $0.45 \lesssim z \lesssim 2.25$. We present the observational properties of the GA, and we assess it statistically using methods based on: (i) single-linkage hierarchical clustering (∼4.5σ); (ii) the Cuzick-Edwards test (∼3.0σ); and (iii) power spectrum analysis (∼4.8σ). Each of these methods has distinctive attributes and powers, and we advise considering the evidence from the ensemble. We discuss our approaches to mitigating any post-hoc aspects of analysing significance after discovery. The overdensity of the GA is δρ/ρ ∼ 1.3 ± 0.3. The GA is the newest and one of the largest of a steadily accumulating set of very large LSSs that may (cautiously) challenge the Cosmological Principle, upon which the ‘standard model’ of cosmology is founded. Conceivably, the GA is the precursor of a structure like the Sloan Great Wall (but the GA is about twice the size), seen when the Universe was about half its present age.

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Large-scale clustering amongst Fermi blazars; evidence for axis alignments?

Cited by 12 publications

References 51 publications

Analysis of spin directions of galaxies in the DESI Legacy Survey

Analysis of spin directions of galaxies in the DESI Legacy Survey

Using 3D and 2D analysis for analyzing large-scale asymmetry in galaxy spin directions

A Giant Arc on the Sky

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