Cosmography of the Local Universe

Courtois, H. M.; Pomarede, D. M.; Tully, R. Brent; Hoffman, Yehuda; Courtois, Denis

doi:10.1088/0004-6256/146/3/69

Cited by 120 publications

(133 citation statements)

References 45 publications

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“…The MW appears to be located in an unremarkable region away from larger structures such as the Virgo Cluster and the major filaments feeding the Centaurus Cluster (Courtois et al 2013). We therefore reject candidates with similarsized haloes within a neighbourhood of 2 Mpc.…”

Section: Simulationsmentioning

confidence: 98%

Using the Milky Way satellites to study interactions between cold dark matter and radiation

Bœhm¹,

Schewtschenko²,

Wilkinson³

et al. 2014

Monthly Notices of the Royal Astronomical Society: Letters

118

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The cold dark matter (CDM) model faces persistent challenges on small scales. In particular, taken at face value, the model significantly overestimates the number of satellite galaxies around the Milky Way. Attempts to solve this problem remain open to debate and have even led some to abandon CDM altogether. However, current simulations are limited by the assumption that dark matter feels only gravity. Here, we show that including interactions between CDM and radiation (photons or neutrinos) leads to a dramatic reduction in the number of satellite galaxies, alleviating the Milky Way satellite problem and indicating that physics beyond gravity may be essential to make accurate predictions of structure formation on small scales. The methodology introduced here gives constraints on dark matter interactions that are significantly improved over those from the cosmic microwave background.

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Section: Simulationsmentioning

confidence: 98%

Using the Milky Way satellites to study interactions between cold dark matter and radiation

Bœhm¹,

Schewtschenko²,

Wilkinson³

et al. 2014

Monthly Notices of the Royal Astronomical Society: Letters

118

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“…In the bottom panel it is seen that Laniakea gets help rather than hindrance from an opposite void we call "Far Arrowhead." With close inspection it can be seen that there is also a void between Laniakea and the Arrowhead, the "Virgo Void" in Courtois et al (2013), 7 though threaded by the CVn Spur.…”

Section: The Wiener Filter Analysismentioning

confidence: 99%

The Arrowhead Mini-Supercluster of Galaxies

Pomarede

Tully

Hoffman

et al. 2015

ApJ

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Superclusters of galaxies can be defined kinematically from local evaluations of the velocity shear tensor. The location where the smallest eigenvalue of the shear is positive and maximal defines the center of a basin of attraction. Velocity and density fields are reconstructed with Wiener Filter techniques. Local velocities due to the density field in a restricted region can be separated from external tidal flows, permitting the identification of boundaries separating inward flows toward a basin of attraction and outward flows. This methodology was used to define the Laniakea Supercluster that includes the Milky Way. Large adjacent structures include Perseus-Pisces, Coma, Hercules, and Shapley but current kinematic data are insufficient to capture their full domains. However, there is a small region trapped between Laniakea, Perseus-Pisces, and Coma that is close enough to be reliably characterized and that satisfies the kinematic definition of a supercluster. Because of its shape, it is given the name the Arrowhead Supercluster. This entity does not contain any major clusters. A characteristic dimension is ∼25 Mpc and the contained mass is only~ M 10 .15

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“…We use the Cosmicflows-2 (CF2, Tully et al 2013) catalog of distances as a starting point for our Wiener Filter reconstruction (Courtois et al 2012(Courtois et al , 2013. The ∼ 8000 galaxy distances in CF2 are gathered according to the cosmic distance ladder and are thus from an amalgum of six methodologies: Cepheid variables, Tip of the Red Giant Branch, Surface brightness fluctuations, Tully-Fisher relation, Fundamental plane and SuperNovae Ia.…”

Section: Cosmicflows-2 and The Wiener Filter Velocity Field Reconstrumentioning

confidence: 99%

The alignment of galaxy spin with the shear field in observations

Pahwa

Libeskind

Tempel

et al. 2016

Mon. Not. R. Astron. Soc.

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Tidal torque theory suggests that galaxies gain angular momentum in the linear stage of structure formation. Such a theory predicts alignments between the spin of haloes and tidal shear field. However, non-linear evolution and angular momentum acquisition may alter this prediction significantly. In this paper, we use a reconstruction of the cosmic shear field from observed peculiar velocities combined with spin axes extracted from galaxies within 115 Mpc (∼ 8000 kms −1 ) from 2MRS catalog, to test whether or not galaxies appear aligned with principal axes of shear field. Although linear reconstructions of the tidal field have looked at similar issues, this is the first such study to examine galaxy alignments with velocity-shear field. Ellipticals in the 2MRS sample, show a statistically significant alignment with two of the principal axes of the shear field. In general, elliptical galaxies have their short axis aligned with the axis of greatest compression and perpendicular to the axis of slowest compression. Spiral galaxies show no signal. Such an alignment is significantly strengthened when considering only those galaxies that are used in velocity field reconstruction. When examining such a subsample, a weak alignment with the axis of greatest compression emerges for spiral galaxies as well. This result indicates that although velocity field reconstructions still rely on fairly noisy and sparse data, the underlying alignment with shear field is strong enough to be visible even when small numbers of galaxies are considered -especially if those galaxies are used as constraints in the reconstruction.

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Cosmography of the Local Universe

Cited by 120 publications

References 45 publications

Using the Milky Way satellites to study interactions between cold dark matter and radiation

Using the Milky Way satellites to study interactions between cold dark matter and radiation

The Arrowhead Mini-Supercluster of Galaxies

The alignment of galaxy spin with the shear field in observations

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