arXiv subjects

Kevin A. Pimbblet

Publications and source records attributed to Kevin A. Pimbblet.

At least 19 recordsLinked to original sources

arXiv2026

Identification of Cosmic Chronometers in the GAMA Survey

We present a pure sample of 231 massive, passively evolving elliptical galaxies as cosmic chronometer candidates selected from the Galaxy and Mass Assembly (GAMA) survey between $0.03<z<0.4$. The goal of this work is to increase the pool of high-purity cosmic chronometer candidates available in the literature and assess the effect of purity on statistical uncertainty to make $H(z)$ and $H_0$ calculations more robust in future studies. We use traditional selection criteria to identify cosmic chronometers using photometry and spectroscopy in conjunction with modelled parameters such as stellar mass and velocity dispersion. We use an NUVrJ photometric selection to identify quiescent galaxies and identify a number of spectral features, including H$α$, [OII] and H$δ$ to use as tracers for ongoing or recently halted star formation. Additionally, as part of the selection, we calculate the ratio between the Ca II H and K lines to determine whether a galaxy's stellar population is dominated by older or younger stars. We confirm CC candidacy by selecting only the most massive galaxies and perform a visual inspection of the spectra and images of CC candidates. We provide an analysis of the parent sample in comparison to the CC sample and confirm CCs have much lower sSFR, with a median sSFR of $10^{-12}~\text{Myr}^{-1}$. Additionally, we find their median ages are $\sim2~\text{Gyr}$ older than the parent sample.

astro-ph.GA↗

arXiv2026

Rubin J122659.4+090236: An Extremely Low Surface Brightness Galaxy Candidate Discovered in the Rubin LSST Early Data Preview 2

We report the serendipitous discovery of an exceptionally low surface brightness galaxy (LSBG) candidate, Rubin J122659.4+090236, in Rubin Observatory imaging of the interacting NGC 4410 system, identified in the Cosmic Treasure Chest public release. 2D Sérsic modelling of the Rubin g, r, and i images reveals a nearly round system with a shallow profile (n ~ 0.4), an effective radius of R_e ~ 6'', and central surface brightnesses of $μ_{0,g}=27.52\pm0.04$, $μ_{0,r}=27.62\pm0.07$, and $μ_{0,i}=27.04\pm0.08$ mag arcsec$^{-2}$. EAZY photo-z fitting favours an intermediate-z solution at z~0.3, while a low-redshift solution at z~0.028, consistent with the NGC 4410 system, is also permitted by a restricted EAZY fit over 0<z<0.1 without imposing a redshift prior. These alternatives imply substantially different physical interpretations, ranging from a diffuse dwarf-like system to an exceptionally extended background LSBG. This discovery demonstrates Rubin's sensitivity to extremely diffuse galaxies and highlights the potential of the LSST survey to uncover large samples of such elusive systems across wide areas, enabling systematic studies of the LSBG population and its role in galaxy evolution.

astro-ph.GA↗

arXiv2026

A search for HI absorption in distant star-forming galaxies with ASKAP-FLASH - II. Direct observations and stacking of 21 cm line

We present results of a search for associated and intervening HI 21 cm absorption in star-forming galaxies and a control sample of radio galaxies at 0.4 < $z$ < 1.0, using ASKAP's FLASH HI 21 cm absorption survey. We report the detection of a new HI 21 cm absorption line in radio galaxy NVSS J214954-004657 at $z_{\mathrm{HI}}$ = 0.863. Additionally, we present results of HI 21 cm stacking for associated and intervening star-forming and radio galaxy catalogues. For the first time at these redshifts, we report tentative detections of stacked HI 21 cm absorption for associated galaxies when stacked in order of descending radio source brightness, and show that these tentative detections become buried as optical depth increases as progressively weaker sources are co-added into the stack. No stacked signal is detected when co-adding intervening galaxy spectra. We speculate that the ability to detect a stacked HI 21 cm detection is dependent on the background source optical depth limits, as well as source covering factors. Covering factor has a greater impact when stacking intervening systems, and can be considered to effectively weaken the observed flux density of a radio source. We find no significant difference in detection rate for associated HI 21 cm absorption in star-forming galaxies versus the general radio-source population at the same redshift. Although detection rates are low, from a meta-analysis of HI 21 cm surveys we find that 1 detection is expected given the survey parameters.

astro-ph.GA↗

arXiv2025

The First Large Absorption Survey in HI (FLASH): II. Pilot Survey data release and first results

The First Large Absorption Survey in HI (FLASH) is a large-area radio survey for neutral hydrogen in the redshift range 0.4 1$, and appear to be a mixture of intervening and associated systems. Interestingly, around two-thirds of the lines found in this untargeted sample are detected against sources with a peaked-spectrum radio continuum, which are only a minor (5-20%) fraction of the overall radio-source population. The overall detection rate for HI absorption lines in the Pilot Surveys (0.3 to 0.5 lines per ASKAP field) is a factor of two below the expected value. One possible reason for this is the presence of a range of spectral-line artefacts in the Pilot Survey data that have now been mitigated and are not expected to recur in the full FLASH survey. A future paper will discuss the host galaxies of the HI absorption systems identified here.

astro-ph.GA↗

arXiv2024

A catalogue of complex radio sources in the Rapid ASKAP Continuum Survey created using a Self-Organising Map

Next generations of radio surveys are expected to identify tens of millions of new sources, and identifying and classifying their morphologies will require novel and more efficient methods. Self-Organising Maps (SOMs), a type of unsupervised machine learning, can be used to address this problem. We map 251,259 multi-Gaussian sources from Rapid ASKAP Continuum Survey (RACS) onto a SOM with discrete neurons. Similarity metrics, such as Euclidean distances, can be used to identify the best-matching neuron or unit (BMU) for each input image. We establish a reliability threshold by visually inspecting a subset of input images and their corresponding BMU. We label the individual neurons based on observed morphologies and these labels are included in our value-added catalogue of RACS sources. Sources for which the Euclidean distance to their BMU is $\lesssim$ 5 (accounting for approximately 79$\%$ of sources) have an estimated $>90\%$ reliability for their SOM-derived morphological labels. This reliability falls to less than 70$\%$ at Euclidean distances $\gtrsim$ 7. Beyond this threshold it is unlikely that the morphological label will accurately describe a given source. Our catalogue of complex radio sources from RACS with their SOM-derived morphological labels from this work will be made publicly available.

astro-ph.GA↗

arXiv2024

Can ChatGPT pass a physics degree? Making a case for reformation of assessment of undergraduate degrees

The emergence of conversational natural language processing models presents a significant challenge for Higher Education. In this work, we use the entirety of a UK physics undergraduate (BSc with Honours) degree including all examinations and coursework to test if ChatGPT (GPT-4) can pass a degree. We adopt a "maximal cheating" approach wherein we permit ourselves to modify questions for clarity, split questions up into smaller sub-components, expand on answers given - especially for long form written responses, obtaining references, and use of advanced coaching, plug-ins and custom instructions to optimize outputs. In general, there are only certain parts of the degree in question where GPT-4 fails. Explicitly these include compulsory laboratory elements, and the final project which is assessed by a viva. If these were no issue, then GPT-4 would pass with a grade of an upper second class overall. In general, coding tasks are performed exceptionally well, along with simple single-step solution problems. Multiple step problems and longer prose are generally poorer along with interdisciplinary problems. We strongly suggest that there is now a necessity to urgently re-think and revise assessment practice in physics - and other disciplines - due to the existence of AI such as GPT-4. We recommend close scrutiny of assessment tasks: only invigilated in-person examinations, vivas, laboratory skills testing (or "performances" in other disciplines), and presentations are not vulnerable to GPT-4, and urge consideration of how AI can be embedded within the disciplinary context.

physics.ed-ph↗

arXiv2024

A search for HI absorption in distant star-forming galaxies with ASKAP-FLASH -- I. Selection and analysis of the radio sample

We present and discuss two catalogues of UV-selected (NUV $< 22.8$ mag) galaxies that lie within a 200 deg$^2$ area of sky covered by the ASKAP FLASH survey and have an impact parameter of less than 20 arcsec to a FLASH radio continuum source. These catalogues are designed to enable a future search for 21 cm HI absorption in and around star-forming galaxies at redshift $0.4 80 percent) star-forming and resemble the overall WiggleZ population. The ($g - i$) colour evolution with redshift is consistent with a history of active star-formation, but the radio-associated objects are typically redder and have colours similar to high-excitation radio galaxies. The redshift distribution of the two catalogues matches the overall distribution for WiggleZ galaxies, despite their otherwise rare radio properties. These catalogues can be expanded in future as new radio data become available, and a forthcoming paper will present the HI absorption results.

astro-ph.GA↗

arXiv2024

The Galaxy Zoo Catalogs for the Galaxy And Mass Assembly (GAMA) Survey

Galaxy Zoo is an online project to classify morphological features in extra-galactic imaging surveys with public voting. In this paper, we compare the classifications made for two different surveys, the Dark Energy Spectroscopic Instrument (DESI) imaging survey and a part of the Kilo-Degree Survey (KiDS), in the equatorial fields of the Galaxy And Mass Assembly (GAMA) survey. Our aim is to cross-validate and compare the classifications based on different imaging quality and depth. We find that generally the voting agrees globally but with substantial scatter i.e. substantial differences for individual galaxies. There is a notable higher voting fraction in favor of ``smooth'' galaxies in the DESI+\rev{\sc zoobot} classifications, most likely due to the difference between imaging depth. DESI imaging is shallower and slightly lower resolution than KiDS and the Galaxy Zoo images do not reveal details such as disk features \rev{and thus are missed in the {\sc zoobot} training sample}. \rev{We check against expert visual classifications and find good agreement with KiDS-based Galaxy Zoo voting.} We reproduce the results from Porter-Temple+ (2022), on the dependence of stellar mass, star-formation, and specific star-formation on the number of spiral arms. This shows that once corrected for redshift, the DESI Galaxy Zoo and KiDS Galaxy Zoo classifications agree well on population properties. The zoobot cross-validation increases confidence in its ability to compliment Galaxy Zoo classifications and its ability for transfer learning across surveys.

astro-ph.GA↗

arXiv2022

Galaxy and Mass Assembly (GAMA): Extended Intra-Group Light in a group at $z=0.2$ from deep Hyper-Suprime Cam images

We present a pilot study to assess the potential of Hyper Suprime-Cam Public Data Release 2 (HSC-PDR2) images for the analysis of extended faint structures within groups of galaxies. We examine the intra-group light (IGL) of the group 400138 ($M_{\rm{dyn}}= 1.3 \pm 0.5 \times 10^{13} $M$_{\odot}$, $z\sim 0.2$) from the Galaxy And Mass Assembly (GAMA) survey using Hyper-Suprime Cam Subaru Strategic Program Public Data Release 2 (HSC-PDR2) images in $g$, $r$, and $i$ bands. We present the most extended IGL measurement to date, reaching down to $μ_{g}^{\rm{lim}}=30.76$ mag arcsec$^{-2}$ ($3 σ$; $10 \times 10$ arcsec$^{2}$) at a semi-major axis of 275 kpc. The IGL shows mean colour values of $g-i=0.92$, $g-r=0.60$, and $r-i=0.32$ ($\pm$0.01). The IGL stellar populations are younger ($2-2.5$ Gyr) and less metal-rich ([Fe/H] $ \sim -$0.4) than those of the host group galaxies. We find a range of IGL fractions as a function of total group luminosity of $\sim 2-36 \%$ depending on the definition of IGL, with larger fractions the bluer the observation wavelength. The early-type to late-type galaxy ratio suggests that 400138 is a more evolved group, dominated by ETGs, and the IGL fraction agrees with that of other similarly evolved groups. These results are consistent with tidal stripping of the outer parts of Milky Way-like galaxies as the main driver of the IGL build-up. This is supported by the detection of substructure in the IGL towards the galaxy member 1660615 suggesting a recent interaction ($<1$ Gyr ago) of that galaxy with the core of the group.

astro-ph.GA↗

arXiv2022

Galaxy And Mass Assembly: Galaxy Morphology in the Green Valley, Prominent rings and looser Spiral Arms

Galaxies broadly fall into two categories: star-forming (blue) galaxies and quiescent (red) galaxies. In between, one finds the less populated ``green valley". Some of these galaxies are suspected to be in the process of ceasing their star-formation through a gradual exhaustion of gas supply or already dead and are experiencing a rejuvenation of star-formation through fuel injection. We use the Galaxy And Mass Assembly database and the Galaxy Zoo citizen science morphological estimates to compare the morphology of galaxies in the green valley against those in the red sequence and blue cloud. Our goal is to examine the structural differences within galaxies that fall in the green valley, and what brings them there. Previous results found disc features such as rings and lenses are more prominently represented in the green valley population. We revisit this with a similar sized data set of galaxies with morphology labels provided by the Galaxy Zoo for the GAMA fields based on new KiDS images. Our aim is to compare qualitatively the results from expert classification to that of citizen science. We observe that ring structures are indeed found more commonly in green valley galaxies compared to their red and blue counterparts. We suggest that ring structures are a consequence of disc galaxies in the green valley actively exhibiting characteristics of fading discs and evolving disc morphology of galaxies. We note that the progression from blue to red correlates with loosening spiral arm structure.

astro-ph.GA↗

arXiv2022

Galaxy And Mass Assembly (GAMA): Self-Organizing Map Application on Nearby Galaxies

Galaxy populations show bimodality in a variety of properties: stellar mass, colour, specific star-formation rate, size, and Sérsic index. These parameters are our feature space. We use an existing sample of 7556 galaxies from the Galaxy and Mass Assembly (GAMA) survey, represented using five features and the K-means clustering technique, showed that the bimodalities are the manifestation of a more complex population structure, represented by between 2 and 6 clusters. Here we use Self Organizing Maps (SOM), an unsupervised learning technique which can be used to visualize similarity in a higher dimensional space using a 2D representation, to map these five-dimensional clusters in the feature space onto two-dimensional projections. To further analyze these clusters, using the SOM information, we agree with previous results that the sub-populations found in the feature space can be reasonably mapped onto three or five clusters. We explore where the "green valley" galaxies are mapped onto the SOM, indicating multiple interstitial populations within the green valley population. Finally, we use the projection of the SOM to verify whether morphological information provided by GalaxyZoo users, for example, if features are visible, can be mapped onto the SOM-generated map. Voting on whether galaxies are smooth, likely ellipticals, or "featured" can reasonably be separated but smaller morphological features (bar, spiral arms) can not. SOMs promise to be a useful tool to map and identify instructive sub-populations in multidimensional galaxy survey feature space, provided they are large enough.

astro-ph.GA↗

arXiv2022

Galaxy And Mass Assembly (GAMA): Data Release 4 and the z < 0.1 total and z < 0.08 morphological galaxy stellar mass functions

In Galaxy And Mass Assembly Data Release 4 (GAMA DR4), we make available our full spectroscopic redshift sample. This includes 248682 galaxy spectra, and, in combination with earlier surveys, results in 330542 redshifts across five sky regions covering ~250deg^2. The redshift density, is the highest available over such a sustained area, has exceptionally high completeness (95 per cent to r_KIDS=19.65mag), and is well suited for the study of galaxy mergers, galaxy groups, and the low redshift (z<0.25) galaxy population. DR4 includes 32 value-added tables or Data Management Units (DMUs) that provide a number of measured and derived data products including GALEX, ESO KiDS, ESO VIKING, WISE and Herschel Space Observatory imaging. Within this release, we provide visual morphologies for 15330 galaxies to z<0.08, photometric redshift estimates for all 18million objects to r_KIDS~25mag, and stellar velocity dispersions for 111830 galaxies. We conclude by deriving the total galaxy stellar mass function (GSMF) and its sub-division by morphological class (elliptical, compact-bulge and disc, diffuse-bulge and disc, and disc only). This extends our previous measurement of the total GSMF down to 10^6.75 M_sol h^-2_70 and we find a total stellar mass density of rho_*=(2.97+/-0.04)x10^8 M_sol h_70 Mpc^-3 or Omega_*=(2.17+/-0.03)x10^-3 h^-1_70. We conclude that at z<0.1, the Universe has converted 4.9+/-0.1 per cent of the baryonic mass implied by Big Bang Nucleosynthesis into stars that are gravitationally bound within the galaxy population.

astro-ph.GA↗

arXiv2021

Galaxy and Mass Assembly (GAMA): The Weak Environmental Dependence of Quasar Activity at 0.1<z<0.35

Understanding the connection between nuclear activity and galaxy environment remains critical in constraining models of galaxy evolution. By exploiting extensive catalogued data from the Galaxy and Mass Assembly (GAMA) survey, we identify a representative sample of 205 quasars at 0.1 < z < 0.35 and establish a comparison sample of galaxies, closely matched to the quasar sample in terms of both stellar mass and redshift. On scales <1 Mpc, the galaxy number counts and group membership of quasars appear entirely consistent with those of the matched galaxy sample. Despite this, we find that quasars are ~1.5 times more likely to be classified as the group center, indicating a potential link between quasar activity and cold gas flows or galaxy interactions associated with rich group environments. On scales of ~a few Mpc, the clustering strength of both samples are statistically consistent and beyond 10 Mpc we find no evidence that quasars trace large scale structures any more than the galaxy control sample. Both populations are found to prefer intermediate-density sheets and filaments to either very high- or very low- density environments. This weak dependence of quasar activity on galaxy environment supports a paradigm in which quasars represent a phase in the lifetime of all massive galaxies and in which secular processes and a group-centric location are the dominant trigger of quasars at low redshift.

astro-ph.GA↗

arXiv2020

The Impact of Disturbed Galaxy Clusters on the Kinematics of Active Galactic Nuclei

We produce a kinematic analysis of AGN-hosting cluster galaxies from a sample 33 galaxy clusters selected using the X-ray Clusters Database (BAX) and populated with galaxies from the Sloan Digital Sky Survey (SDSS) Data Release 8 (DR8). The 33 galaxy clusters are delimited by their relative intensity of member galaxy substructuring as a proxy to core merging to derive two smaller sub-samples of 8 dynamically active (merging) and 25 dynamically relaxed (non-merging) states. The AGN were selected for each cluster sub-sample by employing the WHAN diagram to the strict criteria of log$_{10}$([NII]/H$α$)$\geq-0.32$ and EW$_{\mathrm{H}α}$ $\geq$ 6Å, providing pools of 70 merging and 225 non-merging AGN sub-populations. By co-adding the clusters to their respective dynamical states to improve the signal-to-noise of our AGN sub-populations we find that merging galaxy clusters on average host kinematically active AGN between 0-1.5 $r_{200}$ as $r_{200}\rightarrow0$, where their velocity dispersion profile (VDP) presents a significant deviation from the non-AGN sub-population VDP by $\gtrsim3σ$. This result is indicative that the AGN-hosting cluster galaxies have recently coalesced onto a common potential. Further analysis of the composite distributions illustrate non-merging AGN-hosting sub-populations have, on average, already been accreted and predominantly lie within backsplash regions of the projected phase-space. This suggests merging cluster dynamical states hold relatively younger AGN sub-populations kinematically compared with those found in non-merging cluster dynamical states.

astro-ph.GA↗

arXiv2019

The Rotational Profiles of Cluster Galaxies

We compile two samples of cluster galaxies with complimentary hydrodynamic and N-body analysis using FLASH code to ascertain how their differing populations drive their rotational profiles and to better understand their dynamical histories. We select our main cluster sample from the X-ray Galaxy Clusters Database (BAX), which are populated with Sloan Digital Sky Survey (SDSS) galaxies. The BAX clusters are tested for the presence of sub-structures, acting as proxies for core mergers, culminating in sub-samples of 8 merging and 25 non-merging galaxy clusters. An additional sample of 12 galaxy clusters with known dumbbell components is procured using galaxy data from the NASA/IPAC Extragalactic Database (NED) to compare against more extreme environments. BAX clusters of each sample are stacked onto a common RA-DEC space to produce rotational profiles within the range of $0.0 - 2.5$ $r_{200}$. Merging stacks possess stronger core rotation at $\lesssim 0.5 r_{200}$ primarily contributed by a red galaxy sub-population from relaxing core mergers, this is alongside high rotational velocities from blue galaxy sub-populations, until, they mix and homogenise with the red sub-populations at $\sim r_{200}$, indicative of an infalling blue galaxy sub-population with interactive mixing between both sub-populations at $\gtrsim r_{200}$. FLASH code is utilised to simulate the merger phase between two originally independent clusters and test the evolution of their rotational profiles. Comparisons with the dumbbell clusters leads to the inference that the peculiar core rotations of some dumbbell clusters are the result of the linear motions of core galaxies relaxing onto the potential during post second infall.

astro-ph.GA↗

arXiv2019

Star-Forming, Rotating Spheroidal Galaxies in the GAMA and SAMI Surveys

The Galaxy And Mass Assembly (GAMA) survey has morphologically identified a class of "Little Blue Spheroid" (LBS) galaxies whose relationship to other classes of galaxies we now examine in detail. Considering a sample of 868 LBSs, we find that such galaxies display similar but not identical colours, specific star formation rates, stellar population ages, mass-to-light ratios, and metallicities to Sd-Irr galaxies. We also find that LBSs typically occupy environments of even lower density than those of Sd-Irr galaxies, where ~65% of LBS galaxies live in isolation. Using deep, high-resolution imaging from VST KiDS and the new Bayesian, two-dimensional galaxy profile modeling code PROFIT, we further examine the detailed structure of LBSs and find that their Sérsic indices, sizes, and axial ratios are compatible with those of low-mass elliptical galaxies. We then examine SAMI Galaxy survey integral field emission line kinematics for a subset of 62 LBSs and find that the majority (42) of these galaxies display ordered rotation with the remainder displaying disturbed/non-ordered dynamics. Finally, we consider potential evolutionary scenarios for a population with this unusual combination of properties, concluding that LBSs are likely formed by a mixture of merger and accretion processes still recently active in low-redshift dwarf populations. We also infer that if LBS-like galaxies were subjected to quenching in a rich environment, they would plausibly resemble cluster dwarf ellipticals.

astro-ph.GA↗

arXiv2019

The Effect of Minor and Major Mergers on the Evolution of Low Excitation Radio Galaxies

We use deep, $μ_{r} \lesssim 28\,\text{mag}\,\text{arcsec}^{-2}$, $r$-band imaging from the Dark Energy Camera Legacy Survey (DECaLS) to search for past, or ongoing, merger activity in a sample of $282$ Low Excitation Radio Galaxies (LERGs) at $z<0.07$. Our principle aim is to assess the the role of mergers in the evolution of LERGs. Exploiting the imaging depth, we classify tidal remnants around galaxies as both minor and major morphological disturbances for our LERG sample and $1,622$ control galaxies matched in redshift, stellar mass, and environment. In groups and in the field, the LERG minor merger fraction is consistent with the control population. In galaxy clusters, $8.8 \pm 2.9\,$ % of LERGs show evidence of recent minor mergers in contrast to $23.0\pm 2.0\,$ % of controls. This $\sim 4 σ$ deficit of minor mergers in cluster LERGs suggests these events may inhibit this type of nuclear activity for galaxies within the cluster environment. We observe a $> 4σ$ excess of major mergers in the LERGs with $M_{*} \lesssim 10^{11}\,\text{M}_{\odot}$, with $10 \pm 1.5\,$ % of these AGN involved in such large-scale interactions compared to $3.2 \pm 0.4\,$% of control galaxies. This excess of major mergers in LERGs decreases with increasing stellar mass, vanishing by $M_{*} > 10^{11.3}\,\text{M}_{\odot}$. These observations show that minor mergers do not fuel LERGs, and are consistent with typical LERGs being powered by accretion of matter from their halo. Where LERGs are associated with major mergers, these objects may evolve into more efficiently accreting active galactic nuclei as the merger progresses and more gas falls on to the central engine.

astro-ph.GA↗

arXiv2018

The Kinematics of Cluster Galaxies via Velocity Dispersion Profiles

We present an analysis of the kinematics of a sample of 14 galaxy clusters via velocity dispersion profiles (VDPs), compiled using cluster parameters defined within the X-Ray Galaxy Clusters Database (BAX) cross-matched with data from the Sloan Digital Sky Survey (SDSS). We determine the presence of substructure in the clusters from the sample as a proxy for recent core mergers, resulting in 4 merging and 10 non-merging clusters to allow for comparison between their respective dynamical states. We create VDPs for our samples and divide them by mass, colour and morphology to assess how their kinematics respond to the environment. To improve the signal-to-noise ratio our galaxy clusters are normalised and co-added to a projected cluster radius at $0.0 - 2.5$ $r_{200}$. We find merging cluster environments possess an abundance of a kinematically-active (rising VDP) mix of red and blue elliptical galaxies, which is indicative of infalling substructures responsible for pre-processing galaxies. Comparatively, in non-merging cluster environments galaxies generally decline in kinematic activity as a function of increasing radius, with bluer galaxies possessing the highest velocities, likely as a result of fast infalling field galaxies. However, the variance in kinematic activity between blue and red cluster galaxies across merging and non-merging cluster environments suggests galaxies exhibit differing modes of galaxy accretion onto a cluster potential as a function of the presence of a core merger.

astro-ph.GA↗