Is there evidence for anomalous dipole anisotropy in the large-scale structure?

Bengaly, Carlos A. P.; Bernui, Armando; Alcaniz, J. S.; Xavier, H. S.; Novaes, Camila P.

doi:10.1093/mnras/stw2268

Cited by 27 publications

(31 citation statements)

References 131 publications

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“…Besides the temperature data of CMB observations, this dipole anisotropy also manifests itself in polarized data [19,20]. Apart from CMB observations, this dipole anisotropy can be seen in other cosmological observations like large scale structures [21,22] as well. For example, [23] introduced a new method to investigate the possibility of a cosmic anisotropy, through the luminosity distance that enters via the x-ray fluxluminosity conversion, while the temperature measurement is cosmology independent.…”

Section: Introductionmentioning

confidence: 84%

Probing cosmic anisotropy with gravitational waves as standard sirens

Cai

Liu

et al. 2018

Phys. Rev. D

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The gravitational wave (GW) as a standard siren directly determines the luminosity distance from the gravitational waveform without reference to the specific cosmological model, of which the redshift can be obtained separately by means of the electromagnetic counterpart like GW events from binary neutron stars and massive black hole binaries (MBHBs). To see to what extent the standard siren can reproduce the presumed dipole anisotropy written in the simulated data of standard siren events from typical configurations of GW detectors, we find that (1) for the Laser Interferometer Space Antenna with different MBHB models during five-year observations, the cosmic isotropy can be ruled out at 3σ confidence level (C.L.) and the dipole direction can be constrained roughly around 20% at 2σ C.L., as long as the dipole amplitude is larger than 0.03, 0.06 and 0.025 for MBHB models Q3d, pop III and Q3nod with increasing constraining ability, respectively; (2) for Einstein Telescope with no less than 200 standard siren events, the cosmic isotropy can be ruled out at 3σ C.L. if the dipole amplitude is larger than 0.06, and the dipole direction can be constrained within 20% at 3σ C.L. if the dipole amplitude is near 0.1; (3) for the Deci-Hertz Interferometer Gravitational wave Observatory with no less than 100 standard siren events, the cosmic isotropy can be ruled out at 3σ C.L. for dipole amplitude larger than 0.03 , and the dipole direction can even be constrained within 10% at 3σ C.L. if the dipole amplitude is larger than 0.07. Our work manifests the promising perspective of the constraint ability on the cosmic anisotropy from the standard siren approach.

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Section: Introductionmentioning

confidence: 84%

Probing cosmic anisotropy with gravitational waves as standard sirens

Cai

Liu

et al. 2018

Phys. Rev. D

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“…For comparison, we evaluate the constraints using an alternative hemispherical comparison estimator, following Bengaly et al (2018b) (see also Bengaly et al 2017Bengaly et al , 2018a:…”

Section: Appendix B: Alternative Estimatormentioning

confidence: 99%

“…The CMB dipole was measured with high accuracy by the Planck collaboration (Akrami et al 2018): v = 369.82 ± 0.11 km/s towards (264.021 ± 0.011 , 48.253 ± 0.005) • , Measurements performed using these and other radio continuum catalogues have found that the radio dipole is compatible with the CMB dipole direction, but the dipole amplitude is 2 − 5 times larger than the signal observed in the CMB (Blake & Wall 2002;Singal 2011;Gibelyou & Huterer 2012;Rubart & Schwarz 2013;Tiwari et al 2014;Tiwari & Jain 2015;Tiwari & Nusser 2016;Colin et al 2017;Bengaly et al 2018b). However, no significant evidence for anomalous anisotropy in galaxy counts was reported at lower redshift ranges, such as those probed by visible and infrared catalogues (Itoh et al 2010;Gibelyou & Huterer 2012;Yoon et al 2014;Alonso et al 2015a;Yoon & Huterer 2015;Javanmardi & Kroupa 2017;Bengaly et al 2017Bengaly et al , 2018aRameez et al 2018). Measurement of the continuum radio dipole is one of the High-Priority Science Objectives of the SKA, 1 which can be extracted from the same type of survey that will allow us to measure or constrain primordial non-Gaussianity on the largest angular scales .…”

Section: Introductionmentioning

confidence: 98%

Testing the standard model of cosmology with the SKA: the cosmic radio dipole

Bengaly

Siewert

Schwarz

et al. 2019

Monthly Notices of the Royal Astronomical Society

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The dipole anisotropy seen in the cosmic microwave background radiation is interpreted as due to our peculiar motion. The Cosmological Principle implies that this cosmic dipole signal should also be present, with the same direction, in the large-scale distribution of matter. Measurement of the cosmic matter dipole constitutes a key test of the standard cosmological model. Current measurements of this dipole are barely above the expected noise and unable to provide a robust test. Upcoming radio continuum surveys with the SKA should be able to detect the dipole at high signal to noise. We simulate number count maps for SKA survey specifications in Phases 1 and 2, including all relevant effects. Nonlinear effects from local large-scale structure contaminate the cosmic (kinematic) dipole signal, and we find that removal of radio sources at low redshift (z 0.5) leads to significantly improved constraints. We forecast that the SKA could determine the kinematic dipole direction in Galactic coordinates with an error of (∆l, ∆b) ∼ (9 • , 5 • ) to (8 • , 4 • ), depending on the sensitivity. The predicted errors on the relative speed are ∼ 10%. These measurements would significantly reduce the present uncertainty on the direction of the radio dipole, and thus enable the first critical test of consistency between the matter and CMB dipoles.where the direction is given in Galactic coordinates.This dipole is expected to be dominated by the kinematic contribution, which is O(10 2 ) larger than the intrinsic fluctuations in the standard ΛCDM model. Since the cosmic variance of the dipole is very large, significant non-kinematic contributions remain possible and need to be tested by other means. Probing the dipole of the matter distribution in addition to that of the CMB will help to tighten constraints on putative non-kinematic contributions.The extragalactic radio sky offers an excellent opportunity to perform an independent test of the Cosmological Principle. The radio continuum dipole is expected to be dominated by the kinematic dipole. This is not the case for galaxy surveys at visible or infrared wavebands: the number counts in wide area surveys in those wavebands are dominated by objects at redshifts well below unity, so that the large-scale structure dominates over the kinematic signal. By contrast, radio continuum surveys have median redshifts above one, which suppresses the effect of local large-scale structure. Another advantage is that radio waves are not subject to extinction and thus the sky area that can be reliably observed by radio surveys exceeds that of optical and infrared surveys.The largest available wide-area radio continuum surveys include the NRAO VLA Sky Survey (NVSS) (Condon et al. 1998) and the TIFR GMRT Sky Survey (TGSS) (Intema et al. 2016).

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“…Similar tests were done for 2MPZ [34], which also incorporates SuperCOSMOS as one of the input samples, but no significant differences between resulting cosmological parameters were found. We note that the second input sample included in WSC -WISE -does present non-uniformities in the data but not of hemispherical nature, but rather related to the satellite's polar orbit and Moon avoidance maneuvers 11 . Since these non-uniformities are much more involved, we did not investigate their possible impact on our results.…”

Section: Analysis By Hemispheresmentioning

confidence: 94%

All-sky angular power spectra from cleaned WISE×SuperCOSMOS galaxy number counts

Xavier

Costa-Duarte

Balaguera-Antolínez

et al. 2019

J. Cosmol. Astropart. Phys.

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Aiming to extract cosmological information from linear scales of the WISE×SuperCOSMOS photometric redshift catalog, we perform a characterization of the systematic effects associated with stellar content, evidencing the presence of contamination and obscuration. We create an integrated model for these effects (which together we call "usurper contamination"), devise a method to remove both of them simultaneously and show its functionality by applying it to a set of mock catalogs. When administered to WISE×SuperCOSMOS data, our method shows to improve the measurements of angular power spectra on scales 15 and the extraction of cosmological parameters therefrom, even though a significant excess of power remains at these scales. When ignoring scales < 15, we still find strong indications of systematics, albeit these can be localized in the southern equatorial hemisphere. An independent analysis of the northern hemisphere at ≥ 15 agrees with the ΛCDM model with parameters from the Planck satellite and gives Ω c = 0.254 ± 0.020 and Ω b < 0.065 at 95% confidence limit when combined with priors on H 0 , A s and n s . lensing of the cosmic microwave background (CMB) -which serves as a consistency check for our cosmological model, besides helping improve constraints on halo bias and on the amplitude of matter perturbationspeaks at large angular scales [25]. This is also the case for the integrated Sachs-Wolfe effect [26], probed by the cross-correlation of CMB temperature maps with galaxy distribution, whose signal comes from the evolution of gravitational potential along the CMB photon path. Another topic that requires almost full-sky galaxy surveys is the measurement of our own peculiar velocity with respect to all other galaxies [27][28][29]. Large galaxy surveys can also help us improve our understanding of galaxy bias, that could be enhanced at the largest scales if we assume that galaxies form at density peaks (see e.g. [30]).This type of studies are among the main aims of the largest forthcoming surveys. The Large Synoptic Survey Telescope 1 (LSST) [31] will cover 18, 000 deg 2 up to redshifts z 3, while the Euclid space telescope 2 will observe 15,000 deg 2 and detect galaxies up to z 2 [32]. The huge volume probed by these surveys will lead to such a high number of observed galaxies and quasars that spectroscopic measurements will be performed only for a small fraction of them, while for most sources we will have to rely on photometric redshifts (photo-zs hereafter) and photometric classification. These techniques are, however, plagued with high contamination levels, large systematic effects and uncertainties, which must be controlled and understood in order to fully mine the relevant datasets.An existing testbed for such surveys is the WISE×SuperCOSMOS catalog [33] (WSC hereafter), a fullsky photometric galaxy dataset reaching z 0.4. Our goal in this paper is to estimate cosmological parameters from this sample under the standard cosmological model ΛCDM. In this process, we characterize the systematic effects ass...

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Is there evidence for anomalous dipole anisotropy in the large-scale structure?

Cited by 27 publications

References 131 publications

Probing cosmic anisotropy with gravitational waves as standard sirens

Probing cosmic anisotropy with gravitational waves as standard sirens

Testing the standard model of cosmology with the SKA: the cosmic radio dipole

All-sky angular power spectra from cleaned WISE×SuperCOSMOS galaxy number counts

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