Tracing star formation in groups and filaments around a young active galaxy cluster at z ∼ 1.46.
Bibliographic record
Abstract
XMMXCS J2215.9-1738 is one of the most distant spectroscopically confirmed clusters discovered in the X-ray band at a redshift z = 1.46.It is unusual in that it hosts a number of starburst galaxies in its core.In this project we will use optical/IR data taken from the Canada France Hawaii Telescope Legacy Survey Deep 4 (CFHTLS D4) field , along with recent MeerKAT radio observations to survey the large-scale environment around the cluster and study the environmental effects on the star formation of galaxies in groups and filaments around this cluster.This will be the first study that uses radio continnum data to calculate the SFR of J2215 since previous studies have done so using Oii emission (Hayashi et al., 2010) or IR luminosities (e.g Hilton et al., 2009;Ma et al., 2015;Stach et al., 2017).We use EAZY to calculate the photometric redshifts of the optical/infrared galaxies from the WIRCam Deep Survey (WIRDS) catalog and used the redshifts to determine galaxies that are at the cluster redshift through a photometricredshift cut criterion adopted from Hilton et al. (2009).The redshift cut is 1.25 < z p < 1.67 and a total of 30765 galaxies (6.4 % of the total WIRDS catalog) had photometric redshifts found within this range.For galaxies with available spectroscopic redshifts, we considered a criterion where objects with a peculiar velocity that falls within 3 times the velocity dispersion of J2215 as associated with the cluster.A total of 1891 WIRDS galaxies with available spectroscopic redshifts found in the Oii narrowband NB912+NB921 (Hayashi et al., 2017) and GOODS i 0.0 (Stalin et al., 2010) spec-z catalogs were confirmed to be associated with J2215.In total, 31205 galaxies were associated with the cluster through both the methods with duplicates removed.For each galaxy in the WIRDS catalog we integrate the probability distribution function (p(z)) over the redshift interval 1.25 < z p < 1.67 and divide by the pixel area (in Mpc 2 ) to produce a projected WIRDS density map.We mask out all galaxies that do not have NIR data, that is, those that fall outside of the K s band.We then crossmatch the MeerKAT radio source catalog with all the galaxies found at the cluster redshift (31205 sample), and a total of 599 galaxies, which are not AGNs, were associated with a radio source.We use the Bell (2003) relation to calculate the star-formation rates (SFRs) of the 599 galaxies from their radio luminosities and we make a projected SFR per pixel area density map.Like the WIRDS density map, we mask all galaxies that do not have NIR data.Our results show that a filament structure 18.3 Mpc long is located along the east to the south of the cluster.The filament center is 4.41 Mpc ( 5.5R 200 where R 200 is approximately the cluster virial radius 0.8 Mpc) away from the cluster center.Our results qualitatively agree well with the filament structure that is seen in Hayashi et al. (2011) who used Subaru/MOIRCS data (Oii emitters) to trace the filament.From the SFR density map we conclude that the filament contains some star-forming galaxies.I would like to thank Prof. Matt Hilton for his constant supervision, guidance and patience
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".