Assessing the reliability of the Bisous filament finder

Muru, M. M.; Tempel, Elmo

doi:10.1051/0004-6361/202039169

Cited by 8 publications

(11 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Bisous model with different galaxy number densities. The results are presented in Muru & Tempel (2021). In summary, the higher the galaxy input density, the more complete the detected filamentary network compared to the results from highest density data, which we use as a ground truth.…”

Section: Resultsmentioning

confidence: 93%

Detecting cosmic filamentary network with stochastic Bisous model

Muru

2020

Proc. IAU

View full text Add to dashboard Cite

The Bisous model is a tool that uses stochastic methods to detect the network of galactic filaments. This model is explicitly developed to detect the structure from observational data, using only galaxy positions as input. This paper shows that the Bisous model gives reliable results and including photometric data improves the resulting filamentary network. We used MultiDark-Galaxies catalogue to create a mock with photometric redshifts and samples with different galaxy number densities. We found that the filaments detected with the Bisous model are reliable; 85% of the detected filaments are unchanged compared to results with more complete input data. Adding photometric data improves the fraction of galaxies in filaments. Using the confusion matrix technique, we found the false discovery rate to always be below 5% when using photometric data.

show abstract

Section: Resultsmentioning

confidence: 93%

Detecting cosmic filamentary network with stochastic Bisous model

Muru

2020

Proc. IAU

View full text Add to dashboard Cite

show abstract

“…Namely, only galaxies brighter than M r < −18.4 were selected for constructing the Bisous filaments in EAGLE. Essentially, the applied magnitude cut sets a limit for the number density of galaxies (the key property employed by Bisous), and consequently determines the set of detected filaments (Muru & Tempel 2021). By ensuring that the number density of the galaxies used by Bisous was the same for EAGLE and SDSS, we were able to extract a sample of EA-GLE filaments comparable to observations.…”

Section: Filamentsmentioning

confidence: 99%

Cosmic metal invaders: Intergalactic OVII as a tracer of the warm-hot intergalactic medium within cosmic filaments in the EAGLE simulation

Tuominen¹,

Nevalainen²,

Heinämäki³

et al. 2023

Preprint

View full text Add to dashboard Cite

Context. The current observational status of the hot (log T (K) > 5.5) intergalactic medium (IGM) remains incomplete. While recent X-ray emission and Sunyaev-Zeldovich effect observations from stacking large numbers of Cosmic Web filaments have yielded statistically significant detections of this phase, direct statistically significant measurements of single objects remain scarce. The lack of such a sample currently prevents a robust analysis of the cosmic baryon content composed of the hot IGM, which would potentially help solve the cosmological missing baryons problem. Aims. In order to improve the observationally challenging search for the missing baryons, we utilise the theoretical avenue afforded by the EAGLE simulations. Our aim is to get insights into the metal enrichment of the Cosmic Web and the distribution of highly ionised metals in the IGM. Our goal is to aid in the planning of future X-ray observations of the hot intergalactic plasma. Methods. We detected the filamentary network by applying the Bisous formalism to galaxies in the EAGLE simulation. We characterised the spatial distributions of oxygen and O vii and studied their mass and volume filling fractions in the filaments. Since oxygen is formed in and expelled from galaxies, we also studied the surroundings of haloes. We used this information to construct maps of the O vii column density and determine the feasibility of detecting it via absorption with Athena X-IFU. Results. Within EAGLE, the oxygen and O vii number densities drop dramatically beyond the virial radii of haloes. In the most favourable scenario, the median extent of O vii above the Athena X-IFU detection limit is ≈ 700 kpc. Since galaxies are relatively far apart from one another, only ∼ 1% of the filament volumes are filled with O vii at high enough column densities to be detectable by X-IFU. The highly non-homogeneous distribution of the detectable O vii complicates the usage of the measurements of the intergalactic O vii absorbers for tracing the missing baryons and estimating their contribution to the cosmic baryon budget. Instead, the detectable volumes form narrow and dense envelopes around haloes, while the rest of the O vii is diluted at low densities within the full filament volumes. This localised nature, in turn, results in a low chance (∼10-20% per sight line) of detecting intergalactic O vii with Athena X-IFU within the observational SDSS catalogue of nearby filaments. Fortunately, with deeper filament samples, such as those provided via the future 4MOST 4HS survey, the chances of intercepting an absorbing system are expected to increase up to a comfortable level of ∼ 50% per sight line. Conclusions. Based on EAGLE results, targeting the Cosmic Web with Athena may only result in tip-of-the-iceberg detections of the intergalactic O vii, which is located in the galaxy outskirts. This would not be enough to conclusively solve the missing baryon problem. However, the projection of many filaments into a single line of sight will enable a useful X-ray observation strategy...

show abstract

“…3) applied to the data. We used a magnitude limit of −20.0 in the SDSS r-band to have galaxy number density similar to observations (for comparison, see Muru & Tempel 2021). This cut leaves us with 181 411 galaxies in a box with a side of 250 Mpc, and the galaxy number density is 0.0116 Mpc −3 .…”

Section: Simulation Datamentioning

confidence: 99%

Using photometric redshift data to improve the detection of galactic filaments with the Bisous model

Muru

Tempel

2023

A&A

Self Cite

View full text Add to dashboard Cite

Context. Filament finders are limited, among other things, by the abundance of spectroscopic redshift data. This limits the sky areas and depth where we can detect the filamentary network. Aims. As there are proportionally more photometric redshift data than spectroscopic, we aim to use data with photometric redshifts to improve and expand the areas where we can detect the large-scale structure of the Universe. The Bisous model is a filament finder that uses only the galaxy positions. We present a proof of concept, showing that the Bisous filament finder can improve the detected filamentary network with photometric redshift data. Methods. We created mock data from the MULTIDARK-GALAXIES catalogue. Galaxies with spectroscopic redshifts were given exact positions from the simulation. Galaxies with photometric redshifts were given uncertainties along one coordinate. The errors were generated with different Gaussian distributions for different samples. We sample the photometric galaxy positions for each Bisous run based on the uncertainty distribution. In some runs, the sampled positions are closer to the true positions and produce persistent filaments; other runs produce noise, which is suppressed in the post-processing. Results. There are three different types of samples: spectroscopic only, photometric only, and mixed samples of galaxies with photometric and spectroscopic redshifts. In photometric-only samples, the larger the uncertainty for photometric redshifts, the fewer filaments are detected, and the filaments strongly align along the line of sight. Using mixed samples improves the number of filaments detected and decreases the alignment bias of those filaments. The results are compared against the full spectroscopic sample. The recall for photometric-only samples depends heavily on the size of uncertainty and dropped close to 20%; for mixed samples, the recall stayed between 40% and 80%. The false discovery rate stayed below 5% in every sample tested in this work. Mixed samples showed better results than corresponding photometric-only or spectroscopic-only samples for every uncertainty size and number of spectroscopic galaxies in mixed samples. Conclusions. Mixed samples of galaxies with photometric and spectroscopic redshifts help us to improve and extend the large-scale structure further than possible with only spectroscopic samples. Although the uncertainty sizes tested in this work are smaller than those for the available photometric data, upcoming surveys, such as J-PAS, will achieve sufficiently small uncertainties to be useful for large-scale structure detection.

show abstract

Assessing the reliability of the Bisous filament finder

Cited by 8 publications

References 51 publications

Detecting cosmic filamentary network with stochastic Bisous model

Detecting cosmic filamentary network with stochastic Bisous model

Cosmic metal invaders: Intergalactic OVII as a tracer of the warm-hot intergalactic medium within cosmic filaments in the EAGLE simulation

Using photometric redshift data to improve the detection of galactic filaments with the Bisous model

Contact Info

Product

Resources

About