The alignment of galaxy spin with the shear field in observations

Pahwa, Isha; Libeskind, Noam I.; Tempel, Elmo; Hoffman, Yehuda; Tully, R. Brent; Courtois, H. M.; Gottlöber, Stefan; Steinmetz, Matthias; Sorce, Jenny G.

doi:10.1093/mnras/stv2930

Cited by 64 publications

(77 citation statements)

References 59 publications

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“…Lee & Erdogdu 2007;Faltenbacher et al 2009;Li et al 2013;Tempel & Libeskind 2013;Zhang et al 2013;Pahwa et al 2016). There is also agreement with Wang et al (2009) for main galaxies of groups.…”

Section: Early-type Galaxiessupporting

confidence: 64%

Alignment of galaxies relative to their local environment in SDSS-DR8

Hirv

Pelt

Saar

et al. 2017

A&A

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Aims. We study the alignment of galaxies relative to their local environment in SDSS-DR8 and, using these data, we discuss evolution scenarios for different types of galaxies. Methods. We defined a vector field of the direction of anisotropy of the local environment of galaxies. We summed the unit direction vectors of all close neighbours of a given galaxy in a particular way to estimate this field. We found the alignment angles between the spin axes of disc galaxies, or the minor axes of elliptical galaxies, and the direction of anisotropy. The distributions of cosines of these angles are compared to the random distributions to analyse the alignment of galaxies. Results. Sab galaxies show perpendicular alignment relative to the direction of anisotropy in a sparse environment, for single galaxies and galaxies of low luminosity. Most of the parallel alignment of Scd galaxies comes from dense regions, from 2 . . . 3 member groups and from galaxies with low luminosity. The perpendicular alignment of S0 galaxies does not depend strongly on environmental density nor luminosity; it is detected for single and 2 . . . 3 member group galaxies, and for main galaxies of 4 . . . 10 member groups. The perpendicular alignment of elliptical galaxies is clearly detected for single galaxies and for members of ≤10 member groups; the alignment increases with environmental density and luminosity. Conclusions. We confirm the existence of fossil tidally induced alignment of Sab galaxies at low z. The alignment of Scd galaxies can be explained via the infall of matter to filaments. S0 galaxies may have encountered relatively massive mergers along the direction of anisotropy. Major mergers along this direction can explain the alignment of elliptical galaxies. Less massive, but repeated mergers are possibly responsible for the formation of elliptical galaxies in sparser areas and for less luminous elliptical galaxies.

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Section: Early-type Galaxiessupporting

confidence: 64%

Alignment of galaxies relative to their local environment in SDSS-DR8

Hirv

Pelt

Saar

et al. 2017

A&A

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“…This trend was also confirmed observationally by , who found that the spins of high mass ellipticals are preferentially perpendicular while those of bright spiral galaxies are preferentially parallel to their host filaments (see also Cervantes-Sodi et al 2010;Jones et al 2010;Tempel & Libeskind 2013;Zhang et al 2013Zhang et al , 2015Pahwa et al 2016;Hirv et al 2017).…”

Section: Introductionsupporting

confidence: 67%

The Cosmic Ballet II: spin alignment of galaxies and haloes with large-scale filaments in the EAGLE simulation

Veena

Cautun

Tempel

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We investigate the alignment of galaxies and haloes relative to cosmic web filaments using the EAGLE hydrodynamical simulation. We identify filaments by applying the NEXUS+ method to the mass distribution and the Bisous formalism to the galaxy distribution. Both web finders return similar filamentary structures that are well aligned and that contain comparable galaxy populations. EAGLE haloes have an identical spin alignment with filaments as their counterparts in dark matter only simulations: a complex mass dependent trend with low mass haloes spinning preferentially parallel to and high mass haloes spinning preferentially perpendicular to filaments. In contrast, galaxy spins do not show such a spin transition and have a propensity for perpendicular alignments at all masses, with the degree of alignment being largest for massive galaxies. This result is valid for both NEXUS+ and Bisous filaments. When splitting by morphology, we find that elliptical galaxies show a stronger orthogonal spin-filament alignment than spiral galaxies of similar mass. The same is true of their haloes, with the host haloes of elliptical galaxies having a larger degree of orthogonal alignment than the host haloes of spirals. Due to the misalignment between galaxy shape and spin, galaxy minor axes are oriented differently with filaments than galaxy spins. We find that the galaxies whose minor axis is perpendicular to a filament are much better aligned with their host haloes. This suggests that many of the same physical processes determine both the galaxy-filament and the galaxy-halo alignments.

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“…More recent results from larger samples suggested that spiral galaxies are aligned along the intermediate axis of the tidal tensor, in accord with predictions from tidal torque theory (Lee & Pen 2002;Lee & Erdogdu 2007), and are therefore aligned perpendicular to filaments (Jones et al 2010;Zhang et al 2015). However, a number of studies within the past few years have found little support for tidal torque theory predictions and instead suggest that low-mass spiral spins are parallel to filaments while higher mass elliptical or lenticular spins are perpendicular to filaments Tempel & Libeskind 2013;Pahwa et al 2016).…”

Section: Introductionmentioning

confidence: 80%

Alignment between Filaments and Galaxy Spins from the MaNGA Integral-field Survey

Krolewski

Chen

et al. 2019

ApJ

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Halos and galaxies acquire their angular momentum during the collapse of surrounding large-scale structure. This process imprints alignments between galaxy spins and nearby filaments and sheets. Low mass halos grow by accretion onto filaments, aligning their spins with the filaments, whereas high mass halos grow by mergers along filaments, generating spins perpendicular to the filament. We search for this alignment signal using filaments identified with the "Cosmic Web Reconstruction" algorithm applied to the Sloan Digital Sky Survey Main Galaxy Sample and galaxy spins from the MaNGA integral-field unit survey. MaNGA produces a map of the galaxy's rotational velocity, allowing direct measurement of the galaxy's spin direction, or unit angular momentum vector projected onto the sky. We find no evidence for alignment between galaxy spins and filament directions. We do find hints of a mass-dependent alignment signal, which is in 2-3σ tension with the mass-dependent alignment signal in the MassiveBlack-II and Illustris hydrodynamical simulations. However, the tension vanishes when galaxy spin is measured using the Hα emission line velocity rather than stellar velocity. Finally, in simulations we find that the mass-dependent transition from aligned to anti-aligned dark matter halo spins is not necessarily present in stellar spins: we find a stellar spin transition in Illustris but not in MassiveBlack-II, highlighting the sensitivity of spin-filament alignments to feedback prescriptions and subgrid physics.

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The alignment of galaxy spin with the shear field in observations

Cited by 64 publications

References 59 publications

Alignment of galaxies relative to their local environment in SDSS-DR8

Alignment of galaxies relative to their local environment in SDSS-DR8

The Cosmic Ballet II: spin alignment of galaxies and haloes with large-scale filaments in the EAGLE simulation

Alignment between Filaments and Galaxy Spins from the MaNGA Integral-field Survey

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