Revisiting the NVSS number count dipole

Tiwari, Prabhakar; Nusser, Adi

doi:10.1088/1475-7516/2016/03/062

Cited by 111 publications

(142 citation statements)

References 74 publications

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“…The shot noise for the same flux cut is 3.7×10 −5 , this gives an error estimate on dipole magnitude euqal to 0.003. Although this value of dipole is lower than the value 0.070 ± 0.004 obtained in (Bengaly et al 2018), however, it remain 3 to 5 times higher than the value obtained with NVSS for different flux cuts Tiwari & Nusser 2016). The results with mask 2, shown in the bottom panel of figure 3, also show very large C l values for low multipoles l < 10.…”

Section: L Estimationcontrasting

confidence: 51%

“…On the contrary the C l 's from NVSS as computed by ; Nusser & Tiwari (2015); Bengaly et al (2018); Dolfi et al (2019) are found to be roughly consistent with ΛCDM for l > 1. The dipole amplitude from NVSS is more than 2 sigma disagreement with ΛCDM predictions Tiwari & Nusser 2016) whereas the TGSS ADR1 dipole according to Bengaly et al (2018), is almost 5 times larger than the prediction. The Bengaly et al (2018) doubt this excess signal to be physical and say that their results may be due to systematics in data.…”

Section: L Estimationmentioning

confidence: 75%

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The Galaxy Power Spectrum from TGSS ADR1 and the Effect of Flux Calibration Systematics

Tiwari¹,

Ghosh²,

Jain³

2019

ApJ

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We explore the large to moderate scale anisotropy in distant radio sources using the TGSS ADR1 catalog. We use different measures, i.e. number counts, sky brightness and flux per source, for this study. In agreement with earlier results, we report a significant excess of clustering signal above the angular scale of roughly 10 degrees (i.e. l < 20). We find that some survey areas have a systematically low/high flux and argue this may be the cause of the observed signal of excess power at low multipoles. With mocks we demonstrate the effect of such large scale flux systematics and recover TGSS like excess clustering signal by assuming 20% flux uncertainties over ∼ 10 • × 10 • size patches. We argue that that TGSS at this stage, i.e. TGSS ADR1, is not suitable for large scale clustering measurements. We find that the measure, flux per source, shows evidence of isotropy for all multipoles l > 2 despite the presence of systematics in the data. Subject headings: cosmology: large-scale structure of universe -dark matter -galaxies: activehigh-redshift

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Section: L Estimationcontrasting

confidence: 51%

Section: L Estimationmentioning

confidence: 75%

The Galaxy Power Spectrum from TGSS ADR1 and the Effect of Flux Calibration Systematics

Tiwari¹,

Ghosh²,

Jain³

2019

ApJ

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“…E-mail: carlosap@on.br † E-mail: bernui@on.br ‡ E-mail: ivan@fis.unb.br § E-mail: alcaniz@on.br Bernui et al 2007;Abramo et al 2009;Akrami et al 2014;Bernui et al 2014;Ade et al 2015d;Schwarz et al 2016); ii) large velocity flows from analyses of kinematic Sunyaev-Zeldovich effect in GCs (Kashlinsky et al 2009(Kashlinsky et al , 2011Atrio-Barandela et al 2015), although some controversy have been pointed out by Osborne et al (2011), regarding the validity of these results 1 ; iii) large number counts dipole anisotropy found in high-z radio sky (Blake & Wall 2002;Singal 2011;Rubart & Schwarz 2013;Fernández-Cobos et al 2014;Tiwari et al 2015;Tiwari & Nusser 2016). All these results pose a potential challenge for the concordance model of Cosmology, which relies upon the large-scale isotropy assumption.…”

mentioning

confidence: 99%

Probing cosmological isotropy with Planck Sunyaev–Zeldovich galaxy clusters

Bengaly¹,

Bernui²,

Ferreira³

et al. 2016

Mon. Not. R. Astron. Soc.

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We probe the statistical isotropy hypothesis of the large-scale structure with the second Planck Sunyaev-Zeldovich (PSZ2) galaxy clusters data set. Our analysis adopts a statisticalgeometrical method which compares the 2-point angular correlation function of objects in antipodal patches of the sky. Given possible observational biases, such as the presence of anisotropic sky cuts and the non-uniform exposure of Planck's instrumentation, ensembles of Monte Carlo realisations are produced in order to assess the significance of our results. When these observational effects are properly taken into account, we find neither evidence for preferred directions in the sky nor signs of large-angle features in the galaxy clusters celestial distribution. The PSZ2 data set is, therefore, in good concordance with the fundamental hypothesis of large-angle isotropy of cosmic objects.

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“…At the same time, observations of the largely isotropic Hubble expansion and CMB suggest that we are relatively close to the center. This could explain small yet statistically significant (∼ 3σ) anisotropies detected in both the distribution of radio galaxies (Singal 2011;Tiwari and Nusser 2016) and the CMB (Bennett et al 2011;Ade et al 2014), which challenge the isotropy assumption of the ΛCDM model. Note that all anisotropies are expected to disappear when viewed from the exact center of the star.…”

Section: Discussionmentioning

confidence: 99%

Antineutrino Star Model of the Big Bang and Dark Energy

Neiser¹

2018

Preprint

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A new model of cosmology is proposed, where the state of high energy density commonly associated with the big bang is generated by the collapse of an antineutrino star that has exceeded its Chandrasekhar limit. To allow the first neutrino stars and antineutrino stars to form naturally from an initial quantum vacuum state, matter and antimatter are assumed to gravitationally repel. In this scenario, a degenerate antineutrino star in effective hydrostatic equilibrium has a density that is similar to the dark energy density of the ΛCDM model. When viewed from the core, such a star could today accelerate matter radially and emit the isothermal cosmic microwave background radiation, which addresses the horizon and flatness problems. This model and the ΛCDM model are in similar quantitative agreement with supernova distance measurements. The presented model is also in qualitative agreement with observed large-scale anisotropy and inhomogeneity, which distinguishes it from the ΛCDM model.

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Revisiting the NVSS number count dipole

Cited by 111 publications

References 74 publications

The Galaxy Power Spectrum from TGSS ADR1 and the Effect of Flux Calibration Systematics

The Galaxy Power Spectrum from TGSS ADR1 and the Effect of Flux Calibration Systematics

Probing cosmological isotropy with Planck Sunyaev–Zeldovich galaxy clusters

Antineutrino Star Model of the Big Bang and Dark Energy

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