The impact of peculiar velocities on supernova cosmology

Mohayaee, Roya; Rameez, Mohamed; Sarkar, Subir

doi:10.48550/arxiv.2003.10420

Cited by 16 publications

(21 citation statements)

References 24 publications

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“…We take the Pantheon data set, including its various corrections for peculiar velocities, at face value. We are largely interested in higher redshifts and this negates the criticism of Pantheon presented in [38][39][40]. These criticisms cast some suspicion over Pantheon at low redshift, where noticeable departures from Planck-ΛCDM exist [41,42].…”

Section: Discussionmentioning

confidence: 99%

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Hints of FLRW Breakdown from Supernovae

Krishnan,

Mohayaee,

Colgáin

et al. 2021

Preprint

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A 10% difference in the scale for the Hubble parameter constitutes a clear problem for cosmology. As recently observed [1], only a modification to early Universe physics remains as a resolution within Einstein gravity plus the Friedmann-Lemaître-Robertson-Walker (FLRW) paradigm, but the current approaches are unconvincing, since they inflate other tensions. Here, working safely within FLRW and the flat ΛCDM cosmology, we observe that a correlation between higher H0 and the CMB dipole at high redshift, as observed in [1], can be extended from strongly lensed quasars to Pantheon Type Ia supernovae (SN) at > 2σ significance. Taken in tandem with mismatches between the CMB dipole and the dipole inferred from distant radio galaxies and quasars (QSOs), a resolution to Hubble tension outside of FLRW may be currently most compelling.

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Section: Discussionmentioning

confidence: 99%

“…See [43][44][45][46] for previous studies of the cosmological principle in SN and [47,48] for studies within Pantheon. See also [40,50,51] for studies of the impact of peculiar velocities on nearby SN.…”

Section: Discussionmentioning

confidence: 99%

Hints of FLRW Breakdown from Supernovae

Krishnan,

Mohayaee,

Colgáin

et al. 2021

Preprint

Self Cite

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“…of the data across the sky, while the effect of peculiar velocity corrections has also been studied (e.g., Huterer 2020; Mohayaee et al 2020).…”

Section: Scaling Relationmentioning

confidence: 99%

Cosmological implications of the anisotropy of ten galaxy cluster scaling relations

Migkas

Pacaud

Schellenberger

et al. 2021

A&A

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The hypothesis that the late Universe is isotropic and homogeneous is adopted by most cosmological studies, including studies of galaxy clusters. The cosmic expansion rate H0 is thought to be spatially constant, while bulk flows are often presumed to be negligible compared to the Hubble expansion, even at local scales. The effects of bulk flows on the redshift–distance conversion are hence usually ignored. Any deviation from this consensus can strongly bias the results of such studies, and thus the importance of testing these assumptions cannot be understated. Scaling relations of galaxy clusters can be effectively used for this testing. In previous works, we observed strong anisotropies in cluster scaling relations, whose origins remain ambiguous. By measuring many different cluster properties, several scaling relations with different sensitivities can be built. Nearly independent tests of cosmic isotropy and large bulk flows are then feasible. In this work, we make use of up to 570 clusters with measured properties at X-ray, microwave, and infrared wavelengths to construct ten different cluster scaling relations and test the isotropy of the local Universe; to our knowedge, we present five of these scaling relations for the first time. Through rigorous and robust tests, we ensure that our analysis is not prone to generally known systematic biases and X-ray absorption issues. By combining all available information, we detect an apparent 9% spatial variation in the local H0 between (l, b)∼(280°−35°+35°, −15°−20°+20°) and the rest of the sky. The observed anisotropy has a nearly dipole form. Using isotropic Monte Carlo simulations, we assess the statistical significance of the anisotropy to be > 5σ. This result could also be attributed to a ∼900 km s−1 bulk flow, which seems to extend out to at least ∼500 Mpc. These two effects will be indistinguishable until more high-z clusters are observed by future all-sky surveys such as eROSITA.

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“…Exploiting SNe Ia as standard candles, cosmological parameters have been derived, which suggested a Universe with accelerating expansion rate [1][2][3][4][5] Some reservations have recently been expressed on these results [6,7], but these have been refuted elsewhere [8,9]. One important element in these studies is the estimate of the local bulk flow [10]. For instance, no clinching evidence for such bulk flow from type Ia supernovae has been found [11].…”

Section: Introductionmentioning

confidence: 99%

Peculiar motion of Solar system from the Hubble diagram of supernovae Ia and its implications for cosmology

Singal

2021

Preprint

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Peculiar motion of the solar system, determined from the dipole anisotropy in the Cosmic Microwave Background Radiation (CMBR), has given a velocity 370 km s −1 along RA= 168 • , Dec= −7 • . Subsequent peculiar motion determinations from the number counts, sky brightness or redshift dipoles observed in large samples of distant radio galaxies and quasars yielded peculiar velocities two to ten times larger than CMBR, though in all cases the directions matched with the CMBR dipole. Here we introduce a novel technique for determining the peculiar motion from the magnitude-redshift (mB − z) Hubble diagram of Type Ia Supernovae (SN Ia), one of the best standard candles available. We find a peculiar velocity 1.6 ± 0.4 × 10 3 km s −1 , about four times larger than the CMBR value, along RA= 173 • ± 21 • , Dec= 10 • ± 19 • , the direction being within ∼ 1σ of the CMBR dipole. Since a genuine solar motion would not depend upon the method or the dataset employed, large discrepancies seen among various dipole amplitudes could imply that these dipoles, including the CMBR one, might not pertain to observer's peculiar motion. However, a common direction for various dipoles might indicate a preferred direction in the universe, implying an intrinsic anisotropy, in violation of the cosmological principle, a cornerstone of the modern cosmology.

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The impact of peculiar velocities on supernova cosmology

Cited by 16 publications

References 24 publications

Hints of FLRW Breakdown from Supernovae

Hints of FLRW Breakdown from Supernovae

Cosmological implications of the anisotropy of ten galaxy cluster scaling relations

Peculiar motion of Solar system from the Hubble diagram of supernovae Ia and its implications for cosmology

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