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Yifei Luo

Publications and source records attributed to Yifei Luo.

At least 19 recordsLinked to original sources

DRONEAUDIONET: Noise Suppression for Drone Audition-based Search and Rescue

Microphones mounted on UAVs enable aerial acoustic scene analysis applications such as search-and-rescue, wildlife monitoring, and industrial inspection. However, drone rotor noise often dominates the mixture signal at SNRs well below -10 dB, making source recovery extremely challenging. Existing enhancement and source separation methods are typically designed for near-balanced mixtures and degrade substantially in drone audition settings. In this work, we propose DRONEAUDIONET, a drone noise suppression method that reframes a source separation model as a drone noise estimator. To better model drone-dominant mixtures, we introduce a learnable mask-scaling mechanism that allows mask magnitudes beyond unity, together with an additive residual correction term for improved drone estimation and source recovery. We train and evaluate our model on a publicly available drone audition dataset and test generalizability on an out-of-domain dataset with unseen drone hardware and flight modes. Results show that DRONEAUDIONET consistently improves downstream sound classification performance, with the largest gains observed for human vocal sounds. Our findings demonstrate the importance of drone-specific modeling for robust aerial acoustic perception and highlight the potential of source separation methods for real-world drone-assisted search-and-rescue.

cs.SD

Extremely Metal-Poor Galaxies in DESI DR1: Connections to Galaxies in the Early Universe

Extremely Metal-Poor Galaxies (XMPGs), defined as having metallicities below 10\% of the solar value, are considered possible local analogs to primordial systems and offer a unique window into early galaxy evolution. This study presents a large-scale search for XMPGs using data from the Dark Energy Spectroscopic Instrument DR1, systematically evaluating their resemblance to high-redshift galaxies. From a parent sample of over 14 million galaxies, we identify 656 (551 new) confirmed XMPGs and 767 (670 new) high-quality candidates via the direct $T_{\mathrm{e}}$ method. Results reveal that XMPGs follow a distinct star-forming main sequence (SFMS) that is elevated and shallower than that of the comparing star-forming galaxies. Notably, at higher stellar masses ($M_{\star} > 10^{7.5} M_{\odot}$), the XMPG SFMS converges with the sequence observed in high-redshift galaxies by James Webb Space Telescope (JWST), indicating that mature XMPGs sustain star formation rates comparable to their primordial counterparts. Furthermore, XMPGs consistently deviate below the local fundamental metallicity relation, mirroring high-redshift galaxy behavior. These findings demonstrate that XMPGs not only exhibit low metallicities but also preserve scaling relations characteristic of the early Universe, confirming their potential value as local laboratories for studying early galaxy formation processes.

astro-ph.GA

The Merian Survey: A Statistical Census of Bright Satellites of Milky Way Analogs

We present a statistical census of bright, star-forming satellite galaxies around Milky Way (MW) analogs using the first data release of the Merian Survey. Our sample consists of 393 MW analogs with stellar masses $10^{10.5} < M_{\star, \rm host} < 10^{10.9} M_\odot$ at redshifts $0.07 < z < 0.09$, all central galaxies of their own dark matter halos. Using photometric selection -- including magnitude, color, angular size, photometric redshift, and size-mass cuts -- we identify 793 satellite candidates around these 393 hosts. Our selection leverages two medium-band filters targeting H$\alpha$ and [O \textsc{iii}] emission, enabling a nearly complete sample of star-forming, Magellanic Clouds-like satellites with $M_{\star, \rm sat} \gtrsim 10^{8} M_\odot$. We find that $\sim80\%$ of hosts have 0-3 massive satellites, and $13\pm4\%$ have two satellites (similar to the MW). Satellite abundance correlates with total stellar mass, and we provide significantly improved statistics for the most massive satellites at $\log_{10}[M_{\star, \rm sat}/M_{\odot}] \gtrsim 10$. The completeness-corrected radial distribution is less centrally concentrated than an NFW profile. In contrast, the Milky Way satellites are more centrally concentrated than the 50\% richest Merian systems, but are broadly consistent with the 50\% most centrally concentrated Merian systems. Our results highlight the power of medium-band photometry for satellite identification and provide a key benchmark for studying satellite quenching, environmental effects, and hierarchical galaxy formation.

astro-ph.GA

Testing the Stellar Feedback-driven Breathing Mode in Low-mass Galaxies with Gas Kinematics

Hydrodynamic simulations have proposed that stellar feedback and bursty star-formation can produce dark matter cores in low-mass galaxies. A key prediction is that feedback-driven gas outflow and inflow cycles can lead to ``breathing modes'' (rapid fluctuations in the global gravitational potential) which drive correlated variations in galaxy size, kinematics, and star-formation rate. In this paper, we test the dynamical effects of feedback-driven breathing modes using a sample of 103 star-forming low-mass galaxies with stellar masses between $7.9<\rm \log M_*/M_\odot<9.6$ and $0.02<z<0.19$. We measure ionized gas velocity dispersions from H$\alpha$ emission lines and compare them to mock observations from the FIRE-2 simulations. We compare gas velocity dispersions ($\rm \sigma_{gas}$), stellar masses, and specific star-formation rates (sSFR). We find a positive correlation between gas velocity dispersion residuals at fixed stellar masses ($\rm \Delta\sigma_{gas}$) and sSFR in both data and simulations. However, the relation is tighter in FIRE-2 compared to the data. FIRE-2 produces more low-sSFR galaxies compared to our observational sample, however, the sSFR distributions agree after limiting both samples to a minimum sSFR. A deeper and more complete photometric sample further indicates that observed low-mass galaxies could span the full range of sSFR predicted in the FIRE-2 simulations. Our results support the existence of short-timescale dynamical effects driven by gas outflow and inflow cycles in low-mass galaxies and motivate additional tests of the breathing mode.

astro-ph.GA

Relationship between 2D and 3D Galaxy Stellar Mass and Correlations with Halo Mass

Recent studies suggest that the stars in the outer regions of massive galaxies trace halo mass better than the inner regions and that an annular stellar mass provides a low scatter method of selecting galaxy clusters. However, we can only observe galaxies as projected two-dimensional objects on the sky. In this paper, we use a sample of simulated galaxies to study how well galaxy stellar mass profiles in three dimensions correlate with halo mass, and what effects arise when observationally projecting stellar profiles into two dimensions. We compare 2D and 3D outer stellar mass selections and find that they have similar performance as halo mass proxies and that, surprisingly, a 2D selection sometimes has marginally better performance. We also investigate whether the weak lensing profiles around galaxies selected by 2D outer stellar mass suffer from projection effects. We find that the lensing profiles of samples selected by 2D and 3D definitions are nearly identical, suggesting that the 2D selection does not create a bias. These findings underscore the promise of using outer stellar mass as a tool for identifying galaxy clusters.

astro-ph.CO

Merian: A Wide-Field Imaging Survey of Dwarf Galaxies at z~0.06-0.10

We present the Merian Survey, an optical imaging survey optimized for studying the physical properties of bright star-forming dwarf galaxies. Merian is carried out with two medium-band filters ($N708$ and $N540$, centered at $708$ and $540$ nm), custom-built for the Dark Energy Camera (DECam) on the Blanco telescope. Merian covers $\sim 750\,\mathrm{deg}^2$ of equatorial fields, overlapping with the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) wide, deep, and ultra-deep fields. When combined with the HSC-SSP imaging data ($grizy$), the new Merian DECam medium-band imaging allows for photometric redshift measurements via the detection of H$\rm\alpha$ and [OIII] line emission flux excess in the $N708$ and $N540$ filters, respectively, at $0.06<z<0.10$. We present an overview of the survey design, observations taken to date, data reduction using the LSST Science Pipelines, including aperture-matched photometry for accurate galaxy colors, and a description of the data included in the first data release (DR1). The key science goals of Merian include: probing the dark matter halos of dwarf galaxies out to their virial radii using high signal-to-noise weak lensing profile measurements, decoupling the effects of baryonic processes from dark matter, and understanding the role of black holes in dwarf galaxy evolution. This rich dataset will also offer unique opportunities for studying extremely metal-poor galaxies via their strong [OIII] emission and H$\rm\alpha$ lines, as well as [OIII] emitters at $z\sim 0.4$, and Ly$\rm\alpha$ emitters at $z\sim 3.3$ and $z\sim 4.8$. Merian showcases the power of utilizing narrow and medium-band filters alongside broad-band filters for sky imaging, demonstrating their synergistic capacity to unveil astrophysical insights across diverse astrophysical phenomena.

astro-ph.GA

A Nonparametric Morphological Analysis of H$\alpha$ Emission in Bright Dwarfs Using the Merian Survey

Using medium-band imaging from the newly released Merian Survey, we conduct a nonparametric morphological analysis of H$\alpha$ emission maps and stellar continua for a sample of galaxies with $8\lesssim\log (M_\star/M_\odot) < 10.3$ at $0.064<z<0.1$. We present a novel method for estimating the stellar continuum emission through the Merian Survey's N708 medium-band filter, which we use to measure H$\alpha$ emission and produce H$\alpha$ maps for our sample of galaxies with seven-band Merian photometry and available spectroscopy. We measure nonparametric morphological statistics for the H$\alpha$ and stellar continuum images, explore how the morphology of the H$\alpha$ differs from the continuum, and investigate how the parameters evolve with the galaxies' physical properties. In agreement with previous results for more massive galaxies, we find that the asymmetry of the stellar continuum increases with specific star formation rate (SSFR) and we extend the trend to lower masses, also showing that it holds for the asymmetry of the H$\alpha$ emission. We find that the lowest-mass galaxies with the highest SSFR have H$\alpha$ emission that is consistently heterogeneous and compact, while the less active galaxies in this mass range have H$\alpha$ emission that appears diffuse. At higher masses, our data do not span a sufficient range in SSFR to evaluate whether similar trends apply. We conclude that high SSFRs in low-mass galaxies likely result from dynamical instabilities that compress a galaxy's molecular gas to a dense region near the center.

astro-ph.GA

SDSS-IV MaNGA: Stellar rotational support in disk galaxies vs. central surface density and stellar population age

We investigate how the stellar rotational support changes as a function of spatially resolved stellar population age ($\rm D_n4000$) and relative central stellar surface density ($ΔΣ_1$) for MaNGA isolated/central disk galaxies. We find that the galaxy rotational support $λ_{R_\mathrm{e}}$ varies smoothly as a function of $ΔΣ_1$ and $\rm D_n4000$. $\rm D_n4000$ vs. $ΔΣ_1$ follows a "J-shape", with $λ_{R_\mathrm{e}}$ contributing to the scatters. In this "J-shaped" pattern rotational support increases with central $\rm D_n4000$ when $ΔΣ_1$ is low but decreases with $ΔΣ_1$ when $ΔΣ_1$ is high. Restricting attention to low-$ΔΣ_1$ (i.e, large-radius) galaxies, we suggest that the trend of increasing rotational support with $\rm D_n4000$ for these objects is produced by a mix of two different processes, a primary trend characterized by growth in $λ_{R_\mathrm{e}}$ along with mass through gas accretion, on top of which disturbance episodes are overlaid, which reduce rotational support and trigger increased star formation. An additional finding is that star forming galaxies with low $ΔΣ_1$ have relatively larger radii than galaxies with higher $ΔΣ_1$ at fixed stellar mass. Assuming that these relative radii rankings are preserved while galaxies are star forming then implies clear evolutionary paths in central $\rm D_n4000$ vs. $ΔΣ_1$. The paper closes with comments on the implications that these paths have for the evolution of pseudo-bulges vs. classical-bulges. The utility of using $\rm D_n4000$-$ΔΣ_1$ to study $λ_{R_\mathrm{e}}$ reinforces the notion that galaxy kinematics correlate both with structure and with stellar-population state, and indicates the importance of a multi-dimensional description for understanding bulge and galaxy evolution.

astro-ph.GA

Recurrent Context Compression: Efficiently Expanding the Context Window of LLM

To extend the context length of Transformer-based large language models (LLMs) and improve comprehension capabilities, we often face limitations due to computational resources and bounded memory storage capacity. This work introduces a method called Recurrent Context Compression (RCC), designed to efficiently expand the context window length of LLMs within constrained storage space. We also investigate the issue of poor model responses when both instructions and context are compressed in downstream tasks, and propose an instruction reconstruction method to mitigate this problem. We validated the effectiveness of our approach on multiple tasks, achieving a compression rate of up to 32x on text reconstruction tasks with a BLEU4 score close to 0.95, and nearly 100\% accuracy on a passkey retrieval task with a sequence length of 1M. Finally, our method demonstrated competitive performance in long-text question-answering tasks compared to non-compressed methods, while significantly saving storage resources in long-text inference tasks. Our code, models, and demo are available at https://github.com/WUHU-G/RCC_Transformer

cs.CL

The Merian Survey: Design, Construction, and Characterization of a Filter Set Optimized to Find Dwarf Galaxies and Measure their Dark Matter Halo Properties with Weak Lensing

The Merian survey is mapping $\sim$ 850 degrees$^2$ of the Hyper Suprime-Cam Strategic Survey Program (HSC-SSP) wide layer with two medium-band filters on the 4-meter Victor M. Blanco telescope at the Cerro Tololo Inter-American Observatory, with the goal of carrying the first high signal-to-noise (S/N) measurements of weak gravitational lensing around dwarf galaxies. This paper presents the design of the Merian filter set: N708 ($λ_c = 7080 \unicode{x212B}$, $Δλ= 275\unicode{x212B}$) and N540 ($λ_c = 5400\unicode{x212B}$, $Δλ= 210\unicode{x212B}$). The central wavelengths and filter widths of N708 and N540 were designed to detect the $\rm Hα$ and $\rm [OIII]$ emission lines of galaxies in the mass range $8<\rm \log M_*/M_\odot<9$ by comparing Merian fluxes with HSC broad-band fluxes. Our filter design takes into account the weak lensing S/N and photometric redshift performance. Our simulations predict that Merian will yield a sample of $\sim$ 85,000 star-forming dwarf galaxies with a photometric redshift accuracy of $σ_{Δz/(1+z)}\sim 0.01$ and an outlier fraction of $η=2.8\%$ over the redshift range $0.058<z<0.10$. With 60 full nights on the Blanco/Dark Energy Camera (DECam), the Merian survey is predicted to measure the average weak lensing profile around dwarf galaxies with lensing $\rm S/N \sim 32$ within $r<0.5$ Mpc and lensing $\rm S/N \sim 90$ within $r<1.0$ Mpc. This unprecedented sample of star-forming dwarf galaxies will allow for studies of the interplay between dark matter and stellar feedback and their roles in the evolution of dwarf galaxies.

astro-ph.GA

Anomaly detection in Hyper Suprime-Cam galaxy images with generative adversarial networks

The problem of anomaly detection in astronomical surveys is becoming increasingly important as data sets grow in size. We present the results of an unsupervised anomaly detection method using a Wasserstein generative adversarial network (WGAN) on nearly one million optical galaxy images in the Hyper Suprime-Cam (HSC) survey. The WGAN learns to generate realistic HSC-like galaxies that follow the distribution of the data set; anomalous images are defined based on a poor reconstruction by the generator and outlying features learned by the discriminator. We find that the discriminator is more attuned to potentially interesting anomalies compared to the generator, and compared to a simpler autoencoder-based anomaly detection approach, so we use the discriminator-selected images to construct a high-anomaly sample of $\sim$13,000 objects. We propose a new approach to further characterize these anomalous images: we use a convolutional autoencoder to reduce the dimensionality of the residual differences between the real and WGAN-reconstructed images and perform UMAP clustering on these. We report detected anomalies of interest including galaxy mergers, tidal features, and extreme star-forming galaxies. A follow-up spectroscopic analysis of one of these anomalies is detailed in the Appendix; we find that it is an unusual system most likely to be a metal-poor dwarf galaxy with an extremely blue, higher-metallicity HII region. We have released a catalog with the WGAN anomaly scores; the code and catalog are available at https://github.com/kstoreyf/anomalies-GAN-HSC, and our interactive visualization tool for exploring the clustered data is at https://weirdgalaxi.es.

astro-ph.GA

Physical Drivers of Emission Line Diversity of SDSS Seyfert 2s and LINERs After Removal of Contributions by Star Formation

Ionization sources other than HII regions give rise to the right-hand branch in the standard ([NII]) BPT diagram, populated by Seyfert 2s and LINERs. However, because the majority of Seyfert/LINER hosts are star forming (SF), HII regions contaminate the observed lines to some extent, making it unclear if the position along the branch is merely due to various degrees of mixing between pure Seyfert/LINER and SF, or whether it reflects the intrinsic diversity of Seyfert/LINER ionizing sources. In this study, we empirically remove SF contributions in ~100,000 Seyfert/LINERs from SDSS using the doppelganger method. We find that mixing is not the principal cause of the extended morphology of the observed branch. Rather, Seyferts/LINERs intrinsically have a wide range of line ratios. Variations in ionization parameter and metallicity can account for much of the diversity of Seyfert/LINER line ratios, but the hardness of ionization field also varies significantly. Furthermore, our k-means classification on seven decontaminated emission lines reveals that LINERs are made up of two populations, which we call soft and hard LINERs. The Seyfert 2s differ from both types of LINERs primarily by higher ionization parameter, whereas the two LINER types mainly differ from each other (and from star-forming regions) in the hardness of the radiation field. We confirm that the [NII] BPT diagram more efficiently identifies LINERs than [SII] and [OI] diagnostics, because in the latter many LINERs, especially soft ones, occupy the same location as pure star-formers, even after the SF has been removed from LINER emission.

astro-ph.GA

Anomaly Detection in Astronomical Images with Generative Adversarial Networks

We present an anomaly detection method using Wasserstein generative adversarial networks (WGANs) on optical galaxy images from the wide-field survey conducted with the Hyper Suprime-Cam (HSC) on the Subaru Telescope in Hawai'i. The WGAN is trained on the entire sample, and learns to generate realistic HSC-like images that follow the distribution of the training data. We identify images which are less well-represented in the generator's latent space, and which the discriminator flags as less realistic; these are thus anomalous with respect to the rest of the data. We propose a new approach to characterize these anomalies based on a convolutional autoencoder (CAE) to reduce the dimensionality of the residual differences between the real and WGAN-reconstructed images. We construct a subsample of ~9,000 highly anomalous images from our nearly million object sample, and further identify interesting anomalies within these; these include galaxy mergers, tidal features, and extreme star-forming galaxies. The proposed approach could boost unsupervised discovery in the era of big data astrophysics.

astro-ph.GA

The SFR-radius connection: data and implications for wind strength and halo concentration

This paper is one in a series that explores the importance of radius as a second parameter in galaxy evolution. The topic investigated here is the relationship between star formation rate (SFR) and galaxy radius ($R_{\rm e}$) for main-sequence star-forming galaxies. The key observational result is that, over a wide range of stellar mass and redshift in both CANDELS and SDSS, there is little trend between SFR and $R_{\rm e}$ at fixed stellar mass. The Kennicutt-Schmidt law, or any similar density-related star formation law, then implies that smaller galaxies must have lower gas fractions than larger galaxies (at fixed $M_{\ast}$), and this is supported by observations of local star-forming galaxies. We investigate the implication by adopting the equilibrium "bathtub" model: the ISM gas mass is assumed to be constant over time and the net star formation rate is the difference between the accretion rate of gas onto the galaxy from the halo and the outflow rate due to winds. To match the observed null correlation between SFR and radius, the bathtub model requires that smaller galaxies at fixed mass have weaker galactic winds. Our hypothesis is that galaxies are a 2-dimensional family whose properties are set mainly by halo mass and concentration. Galaxy radius and accretion rate plausibly both depend on halo concentration, which predicts how wind strength should vary with $R_{\rm e}$ and SFR.

astro-ph.GA

Quenching as a Contest between Galaxy Halos and their Central Black Holes

Existing models of galaxy formation have not yet explained striking correlations between structure and star-formation activity in galaxies, notably the sloped and moving boundaries that divide star-forming from quenched galaxies in key structural diagrams. This paper uses these and other relations to ``reverse-engineer'' the quenching process for central galaxies. The basic idea is that star-forming galaxies with larger radii (at a given stellar mass) have lower black-hole masses due to lower central densities. Galaxies cross into the green valley when the cumulative effective energy radiated by their black hole equals $\sim4\times$ their halo-gas binding energy. Since larger-radii galaxies have smaller black holes, one finds they must evolve to higher stellar masses in order to meet this halo-energy criterion, which explains the sloping boundaries. A possible cause of radii differences among star-forming galaxies is halo concentration. The evolutionary tracks of star-forming galaxies are nearly parallel to the green-valley boundaries, and it is mainly the sideways motions of these boundaries with cosmic time that cause galaxies to quench. BH-scaling laws for star-forming, quenched, and green-valley galaxies are different, and most BH mass growth takes place in the green valley. Implications include: the radii of star-forming galaxies are an important second parameter in shaping their black holes; black holes are connected to their halos but in different ways for star-forming, quenched, and green-valley galaxies; and the same BH-halo quenching mechanism has been in place since $z \sim 3$. We conclude with a discussion of black hole-galaxy co-evolution, the origin and interpretation of BH scaling laws.

astro-ph.GA

Structural and Stellar Population Properties vs. Bulge Types in Sloan Digital Sky Survey Central Galaxies

This paper studies pseudo-bulges (P-bulges) and classical bulges (C-bulges) in Sloan Digital Sky Survey central galaxies using the new bulge indicator $ΔΣ_1$, which measures relative central stellar-mass surface density within 1 kpc. We compare $ΔΣ_1$ to the established bulge-type indicator $Δ\langleμ_e\rangle$ from Gadotti (2009) and show that classifying by $ΔΣ_1$ agrees well with $Δ\langleμ_e\rangle$. $ΔΣ_1$ requires no bulge-disk decomposition and can be measured on SDSS images out to $z = 0.07$. Bulge types using it are mapped onto twenty different structural and stellar-population properties for 12,000 SDSS central galaxies with masses 10.0 < log $M_*$/$M_{\odot}$ < 10.4. New trends emerge from this large sample. Structural parameters show fairly linear log-log relations vs. $ΔΣ_1$ and $Δ\langleμ_e\rangle$ with only moderate scatter, while stellar-population parameters show a highly non-linear "elbow" in which specific star-formation rate remains roughly flat with increasing central density and then falls rapidly at the elbow, where galaxies begin to quench. P-bulges occupy the low-density end of the horizontal arm of the elbow and are universally star-forming, while C-bulges occupy the elbow and the vertical branch and exhibit a wide range of star-formation rates at fixed density. The non-linear relation between central density and star-formation rate has been seen before, but this mapping onto bulge class is new. The wide range of star-formation rates in C-bulges helps to explain why bulge classifications using different parameters have sometimes disagreed in the past. The elbow-shaped relation between density and stellar indices suggests that central structure and stellar-populations evolve at different rates as galaxies begin to quench.

astro-ph.GA

The Activation of Galactic Nuclei and Their Accretion Rates are Linked to the Star Formation Rates and Bulge-types of Their Host Galaxies

We use bulge-type classifications of 809 representative SDSS galaxies by Gadotti (2009) to classify a large sample of galaxies into real bulges (classical or elliptical) and pseudobulges using Random Forest. We use structural and stellar population predictors that can easily be measured without image decomposition. Multiple parameters such as the central mass density with 1 kpc, concentration index, Sérsic index and velocity dispersion do result in accurate bulge classifications when combined together. We classify $\sim 44,500$ face-on galaxies above stellar mass of 10$^{10}$ M$_\odot$ and redshift $ 0.02 < z < 0.07$ into real bulges or pseudobulges with $93 \pm 2$\% accuracy. We show that $\sim 75 - 90\%$ of AGNs identified by the optical line ratio diagnostic are hosted by real bulges. The pseudobulge fraction significantly decreases with AGN signature as the line ratios change from indicating pure star formation ($\sim 54 \pm 4$ \%), to composite of star formation and AGN ($\sim 18 \pm 3$\%), and to AGN-dominated galaxies ($\sim 5 \pm 3$\%). Using the dust-corrected [\ion{O}{3}] luminosity as an AGN accretion indicator, and the stellar mass and radius as proxies for a black hole mass, we find that AGNs in real bulges have lower Eddington ratios than AGNs in pseudobulges. Real bulges have a wide range of AGN and star formation activities, although most of them are weak AGNs. For both bulge-types, their Eddington ratios are correlated with specific star formation rates (SSFR). Real bulges have lower specific accretion rate but higher AGN fraction than pseudobulges do at similar SSFRs.

astro-ph.GA

How Accurately Can We Detect the Splashback Radius of Dark Matter Halos and its Correlation With Accretion Rate?

The splashback radius ($R_{\rm sp}$) of dark matter halos has recently been detected using weak gravitational lensing and cross-correlations with galaxies. However, different methods have been used to measure $R_{\rm sp}$ and to assess the significance of its detection. In this paper, we use simulations to study the precision and accuracy to which we can detect the splashback radius with 3D density, 3D subhalo, and weak lensing profiles. We study how well various methods and tracers recover $R_{\rm sp}$ by comparing it with the value measured directly from particle dynamics. We show that estimates of $R_{\rm sp}$ from density and subhalo profiles correspond to different percentiles of the underlying $R_{\rm sp}$ distribution of particle orbits. At low accretion rates, a second caustic appears and can bias results. Finally, we show that upcoming lensing surveys may be able to constrain the splashback-accretion rate relation directly.

astro-ph.GA