The large-scale orientations of disc galaxies

Hahn, Oliver; Teyssier, Romain; Carollo, C. M.

doi:10.1111/j.1365-2966.2010.16494.x

Cited by 134 publications

(183 citation statements)

References 71 publications

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“…The disk galaxies (blue dot-dashed histograms) have very well aligned gas and stellar angular momentum vectors with median values of 7 8 at redshifts z = 2 and z = 0.1 and median values of 6 3 and 7 6 at redshifts z = 1 and z = 0.5, respectively. This is in good agreement with Hahn et al (2010), who found median angles of about 8°for their disks at z = 1 and a median of 7°at redshifts z = 0.5 and z = 0. It demonstrates that the stellar and gaseous disks in disk galaxies are very well aligned, which is what we expect, since the stars form out of the gas and thus maintain the same orientation.…”

Section: The Angle Between Gas and Starssupporting

confidence: 80%

“…They also found that the gas has higher specific angular momentum and spin parameter than the DM. Hahn et al (2010) investigated a sample of about 100 galactic disks and their alignment with their host halo at three different redshifts. Both the stellar and gas disks had a median misalignment angle of about 49°with respect to the hosting DM halo at z = 0.…”

Section: Introductionmentioning

confidence: 99%

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Connecting Angular Momentum and Galactic Dynamics: The Complex Interplay Between Spin, Mass, and Morphology

Teklu

Remus

Dolag

et al. 2015

ApJ

242

253

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The evolution and distribution of the angular momentum of dark matter (DM) halos have been discussed in several studies over the past decades. In particular, the idea arose that angular momentum conservation should allow us to infer the total angular momentum of the entire DM halo from measuring the angular momentum of the baryonic component, which is populating the center of the halo, especially for disk galaxies. To test this idea and to understand the connection between the angular momentum of the DM halo and its galaxy, we use a state-of-the-art, hydrodynamical cosmological simulation taken from the set of Magneticum Pathfinder simulations. Thanks to the inclusion of the relevant physical processes, the improved underlying numerical methods, and high spatial resolution, we successfully produce populations of spheroidal and disk galaxies self-consistently. Thus, we are able to study the dependence of galactic properties on their morphology. We find that(1) the specific angular momentum of stars in disk and spheroidal galaxies as a function of their stellar mass compares well with observational results; (2) the specific angular momentum of the stars in disk galaxies is slightly smaller compared to the specific angular momentum of the cold gas, in good agreement with observations; (3) simulations including the baryonic component show a dichotomy in the specific stellar angular momentum distribution when splitting the galaxies according to their morphological type(this dichotomy can also be seen in the spin parameter, where disk galaxies populate halos with slightly larger spin compared to spheroidal galaxies); (4) disk galaxies preferentially populate halos in which the angular momentum vector of the DM component in the central part shows a better alignment to the angular momentum vector of the entire halo; and (5) the specific angular momentum of the cold gas in disk galaxies is approximately 40% smaller than the specific angular momentum of the total DM halo and shows a significant scatter.

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Section: The Angle Between Gas and Starssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Connecting Angular Momentum and Galactic Dynamics: The Complex Interplay Between Spin, Mass, and Morphology

Teklu

Remus

Dolag

et al. 2015

ApJ

242

253

View full text Add to dashboard Cite

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“…This implies that J 2 , the AM component along the intermediate axis of the inertia tensor of Γ, for which |I 1 − I 3 | refers to the difference between the major and minor eigenvalues, has the highest probability to be the largest AM component (see applications to disc alignment with large-scale structure in Navarro et al 2004;Hahn et al 2010).…”

Section: Summary Of Tidal Torques Theorymentioning

confidence: 99%

Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge

Danovich¹,

Dekel²,

Hahn³

et al. 2015

Monthly Notices of the Royal Astronomical Society

Self Cite

296

377

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We study the angular-momentum (AM) buildup in high-z massive galaxies using highresolution cosmological simulations. The AM originates in co-planar streams of cold gas and merging galaxies tracing cosmic-web filaments, and it undergoes four phases of evolution. (I) Outside the halo virial radius (R v ∼ 100 kpc), the elongated streams gain AM by tidal torques with a specific AM (sAM) ∼ 1.7 times the dark-matter (DM) spin due to the gas' higher quadrupole moment. This AM is expressed as stream impact parameters, from ∼ 0.3R v to counter rotation. (II) In the outer halo, while the incoming DM mixes with the existing halo of lower sAM to a spin λ dm ∼ 0.04, the cold streams transport the AM to the inner halo such that their spin in the halo is ∼ 3λ dm . (III) Near pericenter, the streams dissipate into an irregular rotating ring extending to ∼ 0.3R v and tilted relative to the inner disc. Torques exerted partly by the disc make the ring gas lose AM, spiral in, and settle into the disc within one orbit. The ring is observable with 30% probability as a damped Lyman-α absorber. (IV) Within the disc, < 0.1R v , torques associated with violent disc instability drive AM out and baryons into a central bulge, while outflows remove low-spin gas, introducing certain sensitivity to feedback strength. Despite the different AM histories of gas and DM, the disc spin is comparable to the DM-halo spin. Counter rotation can strongly affect disc evolution.

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“…at small separation both in redshift and on the sky, which allows for a relatively straightforward removal of the II signal from cosmic shear data if photometric redshifts are sufficiently accurate (King & Schneider 2002Heymans & Heavens 2003;Takada & White 2004). The mutual alignment of halo shapes and spins has been studied extensively in N-body simulations (Splinter et al 1997;Onuora & Thomas 2000;Faltenbacher et al 2002;Hopkins et al 2005;Faltenbacher et al 2007Faltenbacher et al , 2008; Lee et al 2008), to a limited degree also including the effect of baryonic physics (van den Bosch et al 2002;Bett et al 2010;Hahn et al 2010). Models for II correlations have been developed analytically or via fits to simulations (Croft & Metzler 2000;Heavens et al 2000;Catelan et al 2001;Crittenden et al 2001;Jing 2002;Mackey et al 2002;, with widely varying results.…”

Section: Introductionmentioning

confidence: 99%

Constraints on intrinsic alignment contamination of weak lensing surveys using the MegaZ-LRG sample

Joachimi¹,

Mandelbaum²,

Abdalla³

et al. 2011

A&A

280

512

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Correlations between the intrinsic shapes of galaxies and the large-scale galaxy density field provide an important tool to investigate galaxy intrinsic alignments, which constitute the major potential astrophysical systematic in cosmological weak lensing (cosmic shear) surveys, but also yield insight into the formation and evolution of galaxies. We measure galaxy position-shape correlations in the MegaZ-LRG sample for more than 800 000 luminous red galaxies for comoving transverse separations of 0.3 < r p < 60 h −1 Mpc, making the first such measurement with a photometric redshift sample. In combination with a re-analysis of several spectroscopic SDSS samples, we constrain an intrinsic alignment model for early-type galaxies over long baselines in redshift (z 0.7) and luminosity (4 mag) with high statistical precision. We develop and test the formalism to incorporate photometric redshift scatter in the modelling of these observations. For r p > 6 h −1 Mpc, the fits to galaxy position-shape correlation functions are consistent with the scaling with r p and redshift of a revised, nonlinear version of the linear alignment model for all samples. An extra redshift dependence ∝ (1 + z) η other is constrained to η other = −0.3 ± 0.8 (1σ). To obtain consistent amplitudes for all data, an additional dependence on galaxy luminosity ∝L β with β = 1.1 +0.3 −0.2 is required. The normalisation of the intrinsic alignment power spectrum is found to be (0.077 ± 0.008) ρ −1 cr for galaxies at redshift 0.3 and r band magnitude of −22 (k-and evolution-corrected to z = 0). Assuming zero intrinsic alignments for blue galaxies, we assess the bias on cosmological parameters for a tomographic CFHTLSlike lensing survey given our new constraints on the intrinsic alignment model parameter space. Both the resulting mean bias and its uncertainty are smaller than the 1σ statistical errors when using the constraints from all samples combined. The addition of MegaZ-LRG data is critical to achieving constraints this strong, reducing the uncertainty in intrinsic alignment bias on cosmological parameters by factors of three to seven.

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The large-scale orientations of disc galaxies

Cited by 134 publications

References 71 publications

Connecting Angular Momentum and Galactic Dynamics: The Complex Interplay Between Spin, Mass, and Morphology

Connecting Angular Momentum and Galactic Dynamics: The Complex Interplay Between Spin, Mass, and Morphology

Four phases of angular-momentum buildup in high-z galaxies: from cosmic-web streams through an extended ring to disc and bulge

Constraints on intrinsic alignment contamination of weak lensing surveys using the MegaZ-LRG sample

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