The Galaxy Alignment Effect in Abell 1689: Evolution, Radial, and Luminosity Dependence

Hung, Li‐Wei; Bañados, Eduardo; Propris, Roberto De; West, Michael J.

doi:10.1088/0004-637x/720/2/1483

Cited by 8 publications

(18 citation statements)

References 29 publications

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“…So far, almost all searches for galaxy alignments have been conducted for relatively nearby clusters owing to the limited depth of readily available ground‐based imaging data. If a study akin to PK05 could be conducted at significantly higher redshift, the presence or absence of galaxy alignments in distant clusters could shed light on the temporal evolution of the effect and thus on the dynamical time‐scales of the physical mechanisms at work (Hung et al 2010). Unfortunately, measuring galaxy orientations from SDSS data is extremely challenging already at low to moderate redshifts due to the poor seeing and insufficient pixel sampling.…”

Section: Introductionmentioning

confidence: 99%

Galaxy alignments in very X-ray luminous clusters at z > 0.5

Hung

Ebeling

2012

Monthly Notices of the Royal Astronomical Society

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We present the results of a search for galaxy alignments in 12 galaxy clusters at z > 0.5, a statistically complete subset of the very X‐ray luminous clusters from the MAssive Cluster Survey (MACS). Using high‐quality images taken with the Hubble Space Telescope (HST) that render measurement errors negligible, we find no radial galaxy alignments within 500 kpc of the cluster centres for a sample of 545 spectroscopically confirmed cluster members. A mild but statistically insignificant trend favouring radial alignments is observed within a radius of 200 kpc and traced to galaxies on the cluster red sequence. Our results for massive clusters at z > 0.5 are in stark contrast to the findings of previous studies which find highly significant radial alignments of galaxies in nearby clusters at z∼ 0.1 out to at least half the virial radius using imaging data from the Sloan Digital Sky Survey (SDSS). The discrepancy becomes even more startling if radial alignment becomes more prevalent at decreasing cluster‐centric distance, as suggested by both ours and previous work. We investigate and discuss potential causes for the disparity between our findings based on HST images of clusters at z > 0.5 and those obtained using ground‐based images of systems at z∼ 0.1. We conclude that the most likely explanation is either dramatic evolution with redshift (in the sense that radial alignments are less pronounced in dynamically younger systems) or the presence of systematic biases in the analysis of SDSS imaging data that cause at least partly spurious alignment signals.

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Section: Introductionmentioning

confidence: 99%

Galaxy alignments in very X-ray luminous clusters at z > 0.5

Hung

Ebeling

2012

Monthly Notices of the Royal Astronomical Society

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“…Further details about the photometry and star/galaxy classification may be found in Leauthaud et al (2007), and we only summarize the most relevant points here. Sextractor is run twice, once with parameters appropriate to the detection and photometry of bright galaxies, without excessively deblending their images, and then with parameters suited to faint galaxies (Hung et al 2010). The same configuration parameters as in Leauthaud et al (2007) are used.…”

Section: Discussionmentioning

confidence: 99%

“…As shown by Holden et al (2009), it is necessary to understand the limits of our method, in order to obtain reliable measurements of the galaxy position angle. This is complicated and depends on the spatial resolution of the image, the point-spread function (PSF) and the ellipticity of galaxies (Hung et al 2010). Fortunately, our method is the same as that used by Hung et al (2010), Figure 1.…”

Section: Discussionmentioning

confidence: 99%

“…This is complicated and depends on the spatial resolution of the image, the point-spread function (PSF) and the ellipticity of galaxies (Hung et al 2010). Fortunately, our method is the same as that used by Hung et al (2010), Figure 1. CMDs of the eight clusters.…”

Section: Discussionmentioning

confidence: 99%

“…In highly relaxed clusters, where there has been sufficient time for the exchange of angular momentum of galaxies in multiple galaxy encounters in the dense cluster environment (Coutts 1996), one should not expect to observe any significant primordial galaxy alignment, even if they did originally exist (Plionis et al 2003). Therefore the evolution of the alignment effect offers clues to its origin and dynamical state of a cluster, and can be possibly used to constrain galaxy formation models and their interaction with large-scale structure (Hung et al 2010). Primordial alignment is also an important contamination in weak lensing measurements (Hirata & Seljak 2004).…”

Section: Introductionmentioning

confidence: 99%

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Primordial alignment of elliptical galaxies in intermediate redshift clusters

Zhang

Liao

2015

Mon. Not. R. Astron. Soc.

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We measure primordial alignments for the red galaxies in the sample of eight massive galaxy clusters in the southern sky from the CLASH-VLT Large Programme, at a median redshift of 0.375. We find primordial alignment with about 3σ significance in the four dynamically young clusters, but null detection of primordial alignment in the four highly relaxed clusters. The observed primordial alignment is not dominated by any single one of the four dynamically young clusters, and is primarily due to a population of bright galaxies (M r < −20.5 m) residing in the region 300 − 810 kpc from the cluster centers. For the first time, we point out that the combination of radial alignment and halo alignment can cause fake primordial alignment. Finally, we find that the detected alignment for the dynamically young clusters is real rather than fake primordial alignment.

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The Distribution of Galaxies’ Gravitational Field Stemming From Their Tidal Interaction

Stephanovich

Godlowski

2015

ApJ

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We calculate the distribution function of astronomical objects (like galaxies and/or smooth halos of different kinds) gravitational fields due to their tidal interaction. For that we apply the statistical method of Chandrasekhar (1943), used there to calculate famous Holtzmark distribution. We show that in our approach the distribution function is never Gaussian, its form being dictated by the potential of interaction between objects. This calculation permits us to perform a theoretical analysis of the relation between angular momentum and mass (richness) of the galaxy clusters. To do so, we follow the idea of Catelan & Theuns (1996) and Heavens & Peacock (1988). The main difference is that here we reduce the problem to discrete many-body case, where all physical properties of the system are determined by the interaction potential V (r ij ). The essence of reduction is that we use the multipole (up to quadrupole here) expansion of Newtonian potential so that all hydrodynamic, "extended" characteristics of an object like its density mass are "integrated out" giving its "point-like" characteristics like mass and quadrupole moment. In that sense we make no difference between galaxies and smooth components like halos. We compare our theoretical results with observational data.

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The Galaxy Alignment Effect in Abell 1689: Evolution, Radial, and Luminosity Dependence

Cited by 8 publications

References 29 publications

Galaxy alignments in very X-ray luminous clusters at z > 0.5

Galaxy alignments in very X-ray luminous clusters at z > 0.5

Primordial alignment of elliptical galaxies in intermediate redshift clusters

The Distribution of Galaxies’ Gravitational Field Stemming From Their Tidal Interaction

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