Intrinsic Shapes of Brightest Cluster Galaxies

Nicola, Stefano de; Saglia, R.; Thomas, Jens; Pulsoni, C.; Kluge, Matthias; Bender, R.; Valenzuela, Lucas M.; Remus, Rhea-Silvia

doi:10.3847/1538-4357/ac7463

Cited by 5 publications

(5 citation statements)

References 39 publications

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“…But there has also been interest in the inner region of haloes (e.g. de Nicola et al 2022). We find that the CDM haloes (left-hand side) are more elliptical than the fSIDM haloes (right-hand side).…”

Section: Simulated Haloesmentioning

confidence: 73%

“…It is crucial to be aware of this when comparing simulation results to observations. For example, the deprojection algorithm of de Nicola et al ( 2020) allows observed galaxies to be inferred and it can be used for comparison (de Nicola et al 2022). Interestingly, de Nicola et al (2022) found the shape in the most inner region of the brightest cluster galaxies to become more elliptical, which is in contrast to previous findings where the baryons were found to make haloes more spherical (e.g.…”

Section: Discussionmentioning

confidence: 99%

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Sensitivity of halo shape measurements

Fischer

Valenzuela

2023

A&A

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Shape measurements of galaxies and galaxy clusters are widespread in the analysis of cosmological simulations. But the limitations of those measurements have been poorly investigated. In this Letter, we explain why the quality of the shape measurement does not only depend on the numerical resolution, but also on the density gradient. In particular, this can limit the quality of measurements in the central regions of haloes. We propose a criterion to estimate the sensitivity of the measured shapes based on the density gradient of the halo and to apply it to cosmological simulations of collisionless and self-interacting dark matter. By this, we demonstrate where reliable measurements of the halo shape are possible and how cored density profiles limit their applicability.

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Section: Simulated Haloesmentioning

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Sensitivity of halo shape measurements

Fischer

Valenzuela

2023

A&A

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“…SHAPE3D is able to constrain the range of possible orientations of a triaxial galaxy based on photometric information alone by discarding deprojections where the radial profiles of the flattenings p b a = / and q c a = / (with a being the semimajor, b the semi-intermediate, and c the semiminor axes of a triaxial galaxy) are not smooth (de Nicola et al 2020(de Nicola et al , 2022b. When deprojecting the observed SB of NGC 5419 we apply an rms cutoff rms= ( ( ))  I I ln 0.013 obs fit 2 á ñ for the maximum discrepancy between the observed and modeled surface brightnesses.…”

Section: Triaxial Dynamical Modelingmentioning

confidence: 99%

The Isotropic Center of NGC 5419—A Core in Formation?

Neureiter

Thomas

Rantala

et al. 2023

ApJ

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With its cored surface brightness profile, the elliptical galaxy NGC 5419 appears as a typical high-mass early-type galaxy (ETG). However, the galaxy hosts two distinct nuclei in its center. We use high-signal MUSE (Multi-unit Spectroscopic Explorer (Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 099.B-0193(A).)) spectral observations and novel triaxial dynamical orbit models to reveal a surprisingly isotropic central orbit distribution in NGC 5419. Recent collisionless simulations of merging massive ETGs suggest a two-phase core formation model, in which the low-density stellar core forms rapidly by supermassive black holes (SMBHs) sinking into the center due to dynamical friction. Only afterwards do the SMBHs form a hard binary, and the black hole scouring process slowly changes the central orbit distribution from isotropic to tangential. The observed cored density profile, the double nucleus, and the isotropic center of NGC 5419 together thus point to an intermediate evolutionary state where the first phase of core formation has taken place, yet the scouring process is only beginning. This implies that the double nucleus is an SMBH binary. Our triaxial dynamical models indicate a total mass of the two SMBHs in the center of NGC 5419 of M BH = (1.0 ± 0.08) × 1010 M ⊙. Moreover, we find that NGC 5419's complex kinematically distinct core can be explained by a coherent flip of the direction of orbital rotation of stars on tube orbits at ∼3 kpc distance from the galaxy center together with projection effects. This is also in agreement with merger simulations hosting SMBHs in the same mass regime.

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“…For the purely photometric results, we compare the shape profiles yielded by the deprojections using a similar approach as in de Nicola et al ( 2022), i.e. we consider every deprojection that is qualified as good according to the criteria given in de Nicola et al (2022) and calculate the average < 𝑝(𝑟) >, < 𝑞(𝑟) > among them. The range encompassed by these 'good' deprojections is shown by light-coloured regions in Fig.…”

Section: Shape Recoverymentioning

confidence: 99%

“…Finally, we show how the possible viewing angles of a galaxy can be significantly reduced from photometry alone. This not only helps the dynamical modeling, but also allows us to directly estimate galaxy shapes from photometry alone (de Nicola et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Accuracy and precision of triaxial orbit models – II. Viewing angles, shape, and orbital structure

Nicola

Neureiter

Thomas

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We explore the potential of our novel triaxial modeling machinery in recovering the viewing angles, the shape and the orbit distribution of galaxies by using a high-resolution N-body merger simulation. Our modelling technique includes several recent advancements. (i) Our new triaxial deprojection algorithm SHAPE3D is able to significantly shrink the range of possible orientations of a triaxial galaxy and therefore to constrain its shape relying only on photometric information. It also allows to probe degeneracies, i.e. to recover different deprojections at the same assumed orientation. With this method we can constrain the intrinsic shape of the N-body simulation, i.e. the axis ratios p = b/a and q = c/a, with Δp and Δq ≲ 0.1 using only photometric information. The typical accuracy of the viewing angles reconstruction is 15-20○. (ii) Our new triaxial Schwarzschild code SMART exploits the full kinematic information contained in the entire non-parametric line-of-sight velocity distributions (LOSVDs) along with a 5D orbital sampling in phase space. (iii) We use a new generalised information criterion AICp to optimise the smoothing and to select the best-fit model, avoiding potential biases in purely χ2-based approaches. With our deprojected densities, we recover the correct orbital structure and anisotropy parameter β with Δβ≲ 0.1. These results are valid regardless of the tested orientation of the simulation and suggest that even despite the known intrinsic photometric and kinematic degeneracies the above described advanced methods make it possible to recover the shape and the orbital structure of triaxial bodies with unprecedented accuracy.

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Intrinsic Shapes of Brightest Cluster Galaxies

Cited by 5 publications

References 39 publications

Sensitivity of halo shape measurements

Sensitivity of halo shape measurements

The Isotropic Center of NGC 5419—A Core in Formation?

Accuracy and precision of triaxial orbit models – II. Viewing angles, shape, and orbital structure

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