Fingers-of-God effect of infalling satellite galaxies

Yamamoto, Kazuhiro

doi:10.1093/mnrasl/slv153

Cited by 11 publications

(8 citation statements)

References 47 publications

(56 reference statements)

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“…that is the FT of the one-point PDF, P(u z ) (e.g., Hikage & Yamamoto 2016). Another common velocity PDF is an exponential distribution (e.g., Scoccimarro 2004).…”

Section: Theoretical Background Of Rsdmentioning

confidence: 99%

Radiative transfer distortions of Lyman α emitters: a new Fingers-of-God damping in the clustering in redshift space

Byrohl

Saito

Behrens

2019

Monthly Notices of the Royal Astronomical Society

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Complex radiative transfer (RT) of the Lyman-α photons poses a theoretical challenge to galaxy surveys which infer the large-scale structure with Lyman-α emitters (LAEs). Guided by RT simulations, prior studies investigated the impact of RT on the largescale LAE clustering, and claimed that RT induces a selection effect which results in an anisotropic distortion even in real space but in an otherwise negligible effect in redshift space. However, our previous study, which relies on a full radiative transfer code run on the Illustris simulations, shows that the anisotropic selection effect was drastically reduced with higher spatial resolution. Adopting the same simulation framework, we further study the impact of RT on the LAE clustering in redshift space. Since we measure LAE's radial position through a spectral peak of a Lyman-α emission, the frequency shift due to RT contaminates the redshift measurement and hence the inferred radial position in redshift space. We demonstrate that this additional RT offset suppresses the LAE clustering along the line of sight, which can be interpreted as a novel Fingers-of-God (FoG) effect. To assess the FoG effect, we develop a theoretical framework with particular emphasis on its connection with the underlying one-point velocity distribution which simultaneously takes into account the RT offset as well as the peculiar velocity that is commonly studied in the context of the Redshift Space Distortion (RSD). Although our findings strongly encourage a more careful RSD modeling in LAE surveys, we also seek a method to mitigate the additional FoG effect due to RT by making use of other information in a Lyman-α spectrum.

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“…that is the FT of the one-point PDF, P(u z ) (e.g., Hikage & Yamamoto 2016). Another common velocity PDF is an exponential distribution (e.g., Scoccimarro 2004).…”

Section: Theoretical Background Of Rsdmentioning

confidence: 99%

Radiative transfer distortions of Lyman α emitters: a new Fingers-of-God damping in the clustering in redshift space

Byrohl

Saito

Behrens

2019

Monthly Notices of the Royal Astronomical Society

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“…As discussed in detail in Haines et al (2015), both the width and shape of the LOS velocity distribution of populations of objects in and around galaxy clusters depend strongly on when they have been (or will be) accreted into the cluster. Low LOS velocity dispersions and Gaussian distributions are indicators of virialized populations, while high LOS velocity dispersions and flat top-hat distributions are associated with objects on their first infall (Haines et al 2015;Hikage & Yamamoto 2016).…”

Section: Spatial and Velocity Distribution Of The Infalling X-ray Groupsmentioning

confidence: 99%

LoCuSS: The infall of X-ray groups on to massive clusters

Haines

Finoguenov

Smith

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Galaxy clusters are expected to form hierarchically in a cold dark matter (CDM) universe, growing primarily through mergers with lower mass clusters and the continual accretion of group-mass haloes. Galaxy clusters assemble late, doubling their masses since z ∼ 0.5, and so the outer regions of clusters should be replete with accreting group-mass systems. We present an XMM-Newton survey to search for X-ray groups in the infall regions of 23 massive galaxy clusters (M 200 ∼ 10 15 M) at z ∼ 0.2, identifying 39 X-ray groups that have been spectroscopically confirmed to lie at the cluster redshift. These groups have mass estimates in the range 2 × 10 13-7 × 10 14 M , and group-to-cluster mass ratios as low as 0.02. The comoving number density of X-ray groups in the infall regions is ∼25× higher than that seen for isolated X-ray groups from the XXL survey. The average mass per cluster contained within these X-ray groups is 2.2 × 10 14 M , or 19 ± 5 per cent of the mass within the primary cluster itself. We estimate that ∼10 15 M clusters increase their masses by 16 ± 4 per cent between z = 0.223 and the present day due to the accretion of groups with M 200 ≥ 10 13.2 M. This represents about half of the expected mass growth rate of clusters at these late epochs. The other half is likely to come from smooth accretion of matter not bound within haloes. The mass function of the infalling X-ray groups appears significantly top heavy with respect to that of 'field' X-ray systems, consistent with expectations from numerical simulations, and the basic consequences of collapsed massive dark matter haloes being biased tracers of the underlying large-scale density distribution.

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“…Although not shown here, we have also checked the performance of the special case of simplifying the description of infall velocities with a single Gaussian, as in Hikage & Yamamoto (2016). This results in slightly worse multipoles for the LRG sample, yet reach a similar accuracy in scales s 2Mpc/h.…”

Section: The Clustering Accuracy With Different Descriptions Of Intramentioning

confidence: 99%

“…The line-of-sight velocity distribution of the LRG (top) and the ELG samples (bottom) for satellite galaxies in three host halo mass bins centered in log(M h ) = 13., 13.5., 14.0, shown by the coloured histograms, with colours according to the legend. The solid gray lines correspond to Model C. The dashed gray corresponds to the model ofHikage & Yamamoto (2016). The dotted gray line results from fitting a Gaussian to the distribution of velocities of each galaxy sample.…”

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confidence: 99%

The impact of galaxy formation on satellite kinematics and redshift-space distortions

Orsi

Angulo

2018

Monthly Notices of the Royal Astronomical Society

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Galaxy surveys aim to map the large-scale structure of the Universe and use redshift space distortions to constrain deviations from general relativity and probe the existence of massive neutrinos. However, the amount of information that can be extracted is limited by the accuracy of theoretical models used to analyze the data. Here, by using the L-Galaxies semi-analytical model run over the MXXL N-body simulation, we assess the impact of galaxy formation on satellite kinematics and the theoretical modelling of redshift-space distortions. We show that different galaxy selection criteria lead to noticeable differences in the radial distributions and velocity structure of satellite galaxies. Specifically, whereas samples of stellar mass selected galaxies feature satellites that roughly follow the dark matter, emission line satellite galaxies are located preferentially in the outskirts of halos and display net infall velocities. We demonstrate that capturing these differences is crucial for modelling the multipoles of the correlation function in redshift space, even on large scales. In particular, we show how modelling small scale velocities with a single Gaussian distribution leads to a poor description of the measure clustering. In contrast, we propose a parametrization that is flexible enough to model the satellite kinematics, and that leads to and accurate description of the correlation function down to sub-Mpc scales. We anticipate that our model will be a necessary ingredient in improved theoretical descriptions of redshift space distortions, which together could result in significantly tighter cosmological constraints and a more optimal exploitation of future large datasets.

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Fingers-of-God effect of infalling satellite galaxies

Cited by 11 publications

References 47 publications

Radiative transfer distortions of Lyman α emitters: a new Fingers-of-God damping in the clustering in redshift space

Radiative transfer distortions of Lyman α emitters: a new Fingers-of-God damping in the clustering in redshift space

LoCuSS: The infall of X-ray groups on to massive clusters

The impact of galaxy formation on satellite kinematics and redshift-space distortions

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