{"title":"Towards unbiased recovery of cosmic filament properties: the role of spine curvature and optimized smoothing","authors":"Saee Dhawalikar and Aseem Paranjape","doi":"10.1088/1475-7516/2024/09/041","DOIUrl":null,"url":null,"abstract":"Cosmic filaments, the most prominent features of the cosmic web, possibly hold untapped potential for cosmological inference. While it is natural to expect the structure of filaments to show universality similar to that seen in dark matter halos, the lack of agreement between different filament finders on what constitutes a filament has hampered progress on this topic. We initiate a programme to systematically investigate and uncover possible universal features in the phase space structure of cosmic filaments, by generating particle realizations of mock filaments with a priori known properties. Using these, we identify an important source of bias in the extraction of radial density profiles, which occurs when the local curvature κ of the spine exceeds a threshold determined by the filament thickness. This bias exists even for perfectly determined spines, thus affecting all filament finders. We show that this bias can be nearly eliminated by simply discarding the regions with the highest κ, with little loss of precision. An additional source of bias is the noise generated by the filament finder when identifying the spine, which depends on both the finder algorithm as well as intrinsic properties of the individual filament. We find that to mitigate this bias, it is essential not only to smooth the estimated spine, but to optimize this smoothing separately for each filament. We propose a novel optimization based on minimizing the estimated filament thickness, along with Fourier space smoothing. We implement these techniques using two tools, FilGen which generates mock filaments and FilAPT which analyses and processes them. We expect these tools to be useful in calibrating the performance of filament finders, thereby enabling searches for filament universality.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":null,"pages":null},"PeriodicalIF":5.3000,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Cosmology and Astroparticle Physics","FirstCategoryId":"101","ListUrlMain":"https://doi.org/10.1088/1475-7516/2024/09/041","RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
引用次数: 0
Abstract
Cosmic filaments, the most prominent features of the cosmic web, possibly hold untapped potential for cosmological inference. While it is natural to expect the structure of filaments to show universality similar to that seen in dark matter halos, the lack of agreement between different filament finders on what constitutes a filament has hampered progress on this topic. We initiate a programme to systematically investigate and uncover possible universal features in the phase space structure of cosmic filaments, by generating particle realizations of mock filaments with a priori known properties. Using these, we identify an important source of bias in the extraction of radial density profiles, which occurs when the local curvature κ of the spine exceeds a threshold determined by the filament thickness. This bias exists even for perfectly determined spines, thus affecting all filament finders. We show that this bias can be nearly eliminated by simply discarding the regions with the highest κ, with little loss of precision. An additional source of bias is the noise generated by the filament finder when identifying the spine, which depends on both the finder algorithm as well as intrinsic properties of the individual filament. We find that to mitigate this bias, it is essential not only to smooth the estimated spine, but to optimize this smoothing separately for each filament. We propose a novel optimization based on minimizing the estimated filament thickness, along with Fourier space smoothing. We implement these techniques using two tools, FilGen which generates mock filaments and FilAPT which analyses and processes them. We expect these tools to be useful in calibrating the performance of filament finders, thereby enabling searches for filament universality.
期刊介绍:
Journal of Cosmology and Astroparticle Physics (JCAP) encompasses theoretical, observational and experimental areas as well as computation and simulation. The journal covers the latest developments in the theory of all fundamental interactions and their cosmological implications (e.g. M-theory and cosmology, brane cosmology). JCAP''s coverage also includes topics such as formation, dynamics and clustering of galaxies, pre-galactic star formation, x-ray astronomy, radio astronomy, gravitational lensing, active galactic nuclei, intergalactic and interstellar matter.