Towards robust determination of non-parametric morphologies in marginal astronomical data: resolving uncertainties with cosmological hydrodynamical simulations

Thorp, Mallory; Bluck, Asa F. L.; Ellison, Sara L.; Maiolino, R.; Conselice, Christopher J.; Hani, Maan H.; Bottrell, Connor

doi:10.1093/mnras/stab2201

Cited by 17 publications

(17 citation statements)

References 88 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results are not sensitive to redshift. The typical half-light radius of our sources is ∼2.5 times the PSF size, and we have verified that no strong dependence on redshift can be discerned (Figure 9), consistent with the tests performed by Thorp et al (2021) to evaluate the effect of resolution on asymmetry measurements.…”

Section: Comparing the Asymmetries Of Star-forming Galaxies And Agnssupporting

confidence: 87%

“…This confirms that the uncertainty introduced by the background primarily contributes to the error budget of our A CAS and A outer measurements of the SFGs. Previous studies (e.g., Conselice et al 2000;Thorp et al 2021) found that the asymmetry is dominated by the background noise if the source S/N is below 100. With a typical S/N  100, our galaxies should have reliable asymmetry measurements.…”

Section: Discussionmentioning

confidence: 92%

“…This is expected because A bkg,statmorph is on average close to the median (50th percentile) of the randomly sampled A bkg . Thorp et al (2021) recently also use simulated galaxies to study how to properly correct the background asymmetry. Calculating the background asymmetry from a region offset from the source using statmorph, they find that the intrinsic asymmetry can be recovered best by adopting the measured background asymmetry after scaling it down by ∼15%.…”

Section: Discussionmentioning

confidence: 99%

“…Since the fraction of galaxy mergers depends on the mass of the system (Hopkins et al 2010), we match the stellar mass of the three samples. We further match the redshift distribution of the samples because the galaxy size relative to the spatial resolution also affects asymmetry measurements (Thorp et al 2021). Given the large uncertainty of the individual stellar masses for AGN1s, we first match the distribution of redshifts and stellar masses for the SFGs and AGN2s and then proceed to match the AGN1s to the distributions of SFGs and AGN2s.…”

Section: Sample Selectionmentioning

confidence: 99%

See 3 more Smart Citations

The Relation between Morphological Asymmetry and Nuclear Activity in Low-redshift Galaxies

Zhao

Shangguan

et al. 2022

ApJ

View full text Add to dashboard Cite

The morphology of galaxies reflects their assembly history and ongoing dynamical perturbations from the environment. Analyzing stacked i-band images from the Pan-STARRS1 3π Steradian Survey, we study the optical morphological asymmetry of the host galaxies of a large, well-defined sample of nearby active galactic nuclei (AGNs) to investigate the role of mergers and interactions in triggering nuclear activity. The AGNs, comprising 245 type 1 and 4514 type 2 objects, are compared with 4537 star-forming galaxies (SFGs) matched in redshift (0.04 < z < 0.15) and stellar mass (M * > 1010 M ⊙). We develop a comprehensive masking strategy to isolate the emission of the target from foreground stars and other contaminating nearby sources, all the while retaining projected companions of comparable brightness that may be major mergers. Among three variants of nonparametric indices, both the popular CAS asymmetry parameter (A CAS) and the outer asymmetry parameter (A outer) yield robust measures of morphological distortion for SFGs and type 2 AGNs, while only A outer is effective for type 1 AGNs. The shape asymmetry (A shape), by comparison, is affected more adversely by background noise. Asymmetry indices ≳0.4 effectively trace systems that are candidate ongoing mergers. Contrary to theoretical expectations, galaxy interactions and mergers are not the main drivers of nuclear activity, at least not in our sample of low-redshift, relatively low luminosity AGNs, whose host galaxies are actually significantly less asymmetric than the control sample of SFGs. Moreover, type 2 AGNs are morphologically indistinguishable from their type 1 counterparts. The level of AGN activity does not correlate with asymmetry, not even among the major merger candidates. As a by-product, we find, consistent with previous studies, that the average asymmetry of SFGs increases above the main sequence, although not all major mergers exhibit enhanced star formation.

show abstract

Section: Comparing the Asymmetries Of Star-forming Galaxies And Agnssupporting

confidence: 87%

Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Sample Selectionmentioning

confidence: 99%

See 2 more Smart Citations

The Relation between Morphological Asymmetry and Nuclear Activity in Low-redshift Galaxies

Zhao

Shangguan

et al. 2022

ApJ

View full text Add to dashboard Cite

show abstract

“…signal-to-noise) and choices in preprocessing, models, and optimization routines (e.g. Simard et al 2011;Häußler et al 2013;Mendel et al 2014;Bernardi et al 2014;Meert et al 2015;Bottrell et al 2019a;Thorp et al 2021). Therefore, the second key advantage of: (a) accurately incorporating observational effects (realism) into synthetic observables and (b) using the same tools to analyze the observations and simulations, is that any divergences between recovered properties will be due to their intrinsic differences and not caused by e.g.…”

Section: Introductionmentioning

confidence: 99%

Realistic synthetic integral field spectroscopy with RealSim-IFS

Bottrell,

Hani

2022

Preprint

Self Cite

View full text Add to dashboard Cite

The most direct way to confront observed galaxies with those formed in numerical simulations is to forward-model simulated galaxies into synthetic observations. Provided that synthetic galaxy observations include similar constraints and limitations as real observations, they can be used to (1) carry out even-handed comparisons of observation and theory and (2) map the observable characteristics of simulated galaxies to their a priori known origins. In particular, integral field spectroscopy (IFS) expands the scope of such comparisons and mappings to an exceptionally broad set of physical properties. We therefore present R S -IFS: a tool for forward-modelling galaxies from hydrodynamical simulations into synthetic IFS observations. The core components of R S -IFS model the detailed spatial sampling mechanics of any fibre-bundle, image slicer, or lenslet array IFU and corresponding observing strategy, real or imagined, and support the corresponding propagation of noise adopted by the user. The code is highly generalized and can produce cubes in any light-or mass-weighted quantity (e.g. specific intensity, gas/stellar line-of-sight velocity, stellar age/metallicity, etc.). We show that R S -IFS exactly reproduces the spatial reconstruction of specific intensity and variance cubes produced by the MaNGA survey Data Reduction Pipeline using the calibrated fibre spectra as input. We then apply R S -IFS by producing a public synthetic MaNGA stellar kinematic survey of 893 galaxies with log(M ★ /M ) > 10 from the TNG50 cosmological hydrodynamical simulation.

show abstract

North Ecliptic Pole merging galaxy catalogue

Pearson

Suelves

et al. 2022

A&A

View full text Add to dashboard Cite

Aims. We aim to generate a catalogue of merging galaxies within the 5.4 sq. deg. North Ecliptic Pole over the redshift range 0.0 < z < 0.3. To do this, imaging data from the Hyper Suprime-Cam are used along with morphological parameters derived from these same data. Methods. The catalogue was generated using a hybrid approach. Two neural networks were trained to perform binary merger non-merger classifications: one for galaxies with z < 0.15 and another for 0.15 ≤ z < 0.30. Each network used the image and morphological parameters of a galaxy as input. The galaxies that were identified as merger candidates by the network were then visually checked by experts. The resulting mergers will be used to calculate the merger fraction as a function of redshift and compared with literature results. Results. We found that 86.3% of galaxy mergers at z < 0.15 and 79.0% of mergers at 0.15 ≤ z < 0.30 are expected to be correctly identified by the networks. Of the 34 264 galaxies classified by the neural networks, 10 195 were found to be merger candidates. Of these, 2109 were visually identified to be merging galaxies. We find that the merger fraction increases with redshift, consistent with literature results from observations and simulations, and that there is a mild star-formation rate enhancement in the merger population of a factor of 1.102 ± 0.084.

show abstract

Towards robust determination of non-parametric morphologies in marginal astronomical data: resolving uncertainties with cosmological hydrodynamical simulations

Cited by 17 publications

References 88 publications

The Relation between Morphological Asymmetry and Nuclear Activity in Low-redshift Galaxies

The Relation between Morphological Asymmetry and Nuclear Activity in Low-redshift Galaxies

Realistic synthetic integral field spectroscopy with RealSim-IFS

North Ecliptic Pole merging galaxy catalogue

Contact Info

Product

Resources

About