School of Physics - Research Publications
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ItemNo Preview AvailableMeasurement of gravitational lensing of the cosmic microwave background using SPT-3G 2018 data(American Physical Society, 2023-12-12)
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ItemNo Preview AvailableA Gradual Decline of Star Formation since Cluster Infall: New Kinematic Insights into Environmental Quenching at 0.3 < z < 1.1(IOP Publishing Ltd, 2023-09-01)Abstract The environments where galaxies reside crucially shape their star formation histories. We investigate a large sample of 1626 cluster galaxies located within 105 galaxy clusters spanning a large range in redshift (0.26 < z < 1.13). The galaxy clusters are massive (M 500 ≳ 2 × 1014 M ⊙) and uniformly selected from the SPT and ACT Sunyaev–Zel’dovich surveys. With spectra in hand for thousands of cluster members, we use the galaxies’ position in projected phase space as a proxy for their infall times, which provides a more robust measurement of environment than quantities such as projected clustercentric radius. We find clear evidence for a gradual age increase of the galaxy’s mean stellar populations (∼0.71 ± 0.4 Gyr based on a 4000 Å break, Dn4000) with the time spent in the cluster environment. This environmental quenching effect is found regardless of galaxy luminosity (faint or bright) and redshift (low or high-z), although the exact stellar age of galaxies depends on both parameters at fixed environmental effects. Such a systematic increase of Dn4000 with infall proxy would suggest that galaxies that were accreted into hosts earlier were quenched earlier due to longer exposure to environmental effects such as ram pressure stripping and starvation. Compared to the typical dynamical timescales of 1–3 Gyr of cluster galaxies, the relatively small age increase (∼0.71 ± 0.4 Gyr) found in our sample galaxies seems to suggest that a slow environmental process such as starvation is the dominant quenching pathway. Our results provide new insights into environmental quenching effects spanning a large range in cosmic time (∼5.2 Gyr, z = 0.26–1.13) and demonstrate the power of using a kinematically derived infall time proxy.
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ItemNo Preview AvailableMeasurement of the CMB temperature power spectrum and constraints on cosmology from the SPT-3G 2018 TT, TE, and EE dataset(AMER PHYSICAL SOC, 2023-07-13)
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ItemNo Preview AvailableThe VST ATLAS quasar survey I: Catalogue of photometrically selected quasar candidates(OXFORD UNIV PRESS, 2023-03-23)ABSTRACT We present the VST ATLAS Quasar Survey, consisting of ∼1229 000 quasar (QSO) candidates with 16 < g < 22.5 over ∼4700 deg2. The catalogue is based on VST ATLAS+NEOWISE imaging surveys and aims to reach a QSO sky density of 130 deg−2 for $z$ < 2.2 and ∼30 deg−2 for $z$ > 2.2. To guide our selection, we use X-ray/UV/optical/MIR data in the extended William Herschel Deep Field (WHDF) where we find a g < 22.5 broad-line QSO density of 269 ± 67 deg−2, roughly consistent with the expected ∼196 deg−2. We find that ∼25 per cent of our QSOs are morphologically classed as optically extended. Overall, we find that in these deep data, MIR, UV, and X-ray selections are ∼70–90 per cent complete while X-ray suffers less contamination than MIR and UV. MIR is however more sensitive than X-ray or UV to $z$ > 2.2 QSOs at g < 22.5 and the $S_X(0.5-10\, {\rm keV})\gt 1\times 10^{-14}$ ergs cm−2 s−1 limit of eROSITA. We adjust the selection criteria from our previous 2QDES pilot survey and prioritize VST ATLAS candidates that show both UV and MIR excess, also selecting candidates initially classified as extended. We test our selections using data from DESI (which will be released in DR1) and 2dF to estimate the efficiency and completeness, and we use ANNz2 to determine photometric redshifts. Applying over the ∼4700 deg2 ATLAS area gives us $\sim 917\,000\, z\lt 2.2$ QSO candidates of which 472 000 are likely to be $z$ < 2.2 QSOs, implying a sky density of ∼100 deg−2, which our WHDF analysis suggests will rise to at least 130 deg−2 when eROSITA X-ray candidates are included. At $z$ > 2.2, we find ∼310() 000 candidates, of which 169 000 are likely to be QSOs for a sky density of ∼36 deg−2.
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ItemNo Preview AvailableEvidence for AGN-regulated Cooling in Clusters at z ∼ 1.4: A Multiwavelength View of SPT-CL J0607-4448(IOP Publishing Ltd, 2023-02-01)Abstract We present a multiwavelength analysis of the galaxy cluster SPT-CL J0607-4448 (SPT0607), which is one of the most distant clusters discovered by the South Pole Telescope at z = 1.4010 ± 0.0028. The high-redshift cluster shows clear signs of being relaxed with well-regulated feedback from the active galactic nucleus (AGN) in the brightest cluster galaxy (BCG). Using Chandra X-ray data, we construct thermodynamic profiles and determine the properties of the intracluster medium. The cool-core nature of the cluster is supported by a centrally peaked density profile and low central entropy ( K 0 = 18 − 9 + 11 keV cm2), which we estimate assuming an isothermal temperature profile due to the limited spectral information given the distance to the cluster. Using the density profile and gas cooling time inferred from the X-ray data, we find a mass-cooling rate M ̇ cool = 100 − 60 + 90 M ⊙ yr−1. From optical spectroscopy and photometry around the [O ii] emission line, we estimate that the BCG star formation rate is SFR [ O II ] = 1.7 − 0.6 + 1.0 M ⊙ yr−1, roughly two orders of magnitude lower than the predicted mass-cooling rate. In addition, using ATCA radio data at 2.1 GHz, we measure a radio jet power P cav = 3.2 − 1.3 + 2.1 × 10 44 erg s−1, which is consistent with the X-ray cooling luminosity ( L cool = 1.9 − 0.5 + 0.2 × 10 44 erg s−1 within r cool = 43 kpc). These findings suggest that SPT0607 is a relaxed, cool-core cluster with AGN-regulated cooling at an epoch shortly after cluster formation, implying that the balance between cooling and feedback can be reached quickly. We discuss the implications for these findings on the evolution of AGN feedback in galaxy clusters.
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ItemNo Preview AvailableJoint analysis of Dark Energy Survey Year 3 data and CMB lensing from SPT and Planck. III. Combined cosmological constraints(AMER PHYSICAL SOC, 2023-01-31)
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ItemNo Preview AvailableVST ATLAS galaxy cluster catalogue I: cluster detection and mass calibration(OXFORD UNIV PRESS, 2023-01-28)ABSTRACT Taking advantage of ∼4700 deg2 optical coverage of the Southern sky offered by the VST ATLAS survey, we construct a new catalogue of photometrically selected galaxy groups and clusters using the orca cluster detection algorithm. The catalogue contains ∼22 000 detections with N200 > 10 and ∼9000 with N200 > 20. We estimate the photometric redshifts of the clusters using machine learning and find the redshift distribution of the sample to extend to z ∼ 0.7, peaking at z ∼ 0.25. We calibrate the ATLAS cluster mass-richness scaling relation using masses from the MCXC, Planck, ACT DR5, and SDSS redMaPPer cluster samples. We estimate the ATLAS sample to be $\gt 95~{{\ \rm per\ cent}}$ complete and $\gt 85~{{\ \rm per\ cent}}$ pure at z < 0.35 and in the M200m>$1\times 10^{14}h^{-1}\, \mbox{M}_\odot$ mass range. At z < 0.35, we also find the ATLAS sample to be more complete than redMaPPer, recovering a $\sim 40~{{\ \rm per\ cent}}$ higher fraction of Abell clusters. This higher sample completeness places the amplitude of the z < 0.35 ATLAS cluster mass function closer to the predictions of a ΛCDM model with parameters based on the Planck CMB analyses, compared to the mass functions of the other cluster samples. However, strong tensions between the observed ATLAS mass functions and models remain. We shall present a detailed cosmological analysis of the ATLAS cluster mass functions in paper II. In the future, optical counterparts to X-ray-detected eROSITA clusters can be identified using the ATLAS sample. The catalogue is also well suited for auxiliary spectroscopic target selection in 4MOST. The ATLAS cluster catalogue is publicly available at http://astro.dur.ac.uk/cosmology/vstatlas/cluster_catalogue/.
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ItemCombining Planck and SPT Cluster Catalogs: Cosmological Analysis and Impact on the Planck Scaling Relation Calibration(IOP Publishing, 2022-08-01)We provide the first combined cosmological analysis of the South Pole Telescope (SPT) and Planck cluster catalogs. The aim is to provide an independent calibration for Planck scaling relations, exploiting the cosmological constraining power of the SPT-SZ cluster catalog and its dedicated weak lensing (WL) and X-ray follow-up observations. We build a new version of the Planck cluster likelihood. In the νΛ CDM scenario, focusing on the mass slope and mass bias of Planck scaling relations, we find and , respectively. The results for the mass slope show a ∼4 σ departure from the self-similar evolution, αSZ ∼ 1.8. This shift is mainly driven by the matter density value preferred by SPT data, Ωm = 0.30 ± 0.03, lower than the one obtained by Planck data alone, . The mass bias constraints are consistent both with outcomes of hydrodynamical simulations and external WL calibrations, (1 − b) ∼ 0.8, and with results required by the Planck cosmic microwave background cosmology, (1 − b) ∼ 0.6. From this analysis, we obtain a new catalog of Planck cluster masses M500. We estimate the ratio between the published Planck MSZ masses and our derived masses M500, as a "measured mass bias," . We analyze the mass, redshift, and detection noise dependence of , finding an increasing trend toward high redshift and low mass. These results mimic the effect of departure from self-similarity in cluster evolution, showing different dependencies for the low-mass, high-mass, low-z, and high-z regimes.
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ItemImproving Cosmological Constraints from Galaxy Cluster Number Counts with CMB-cluster-lensing Data: Results from the SPT-SZ Survey and Forecasts for the Future(IOP Publishing Ltd, 2022-06-01)Abstract We show the improvement to cosmological constraints from galaxy cluster surveys with the addition of cosmic microwave background (CMB)-cluster lensing data. We explore the cosmological implications of adding mass information from the 3.1σ detection of gravitational lensing of the CMB by galaxy clusters to the Sunyaev–Zel’dovich (SZ) selected galaxy cluster sample from the 2500 deg2 SPT-SZ survey and targeted optical and X-ray follow-up data. In the ΛCDM model, the combination of the cluster sample with the Planck power spectrum measurements prefers σ 8 Ω m / 0.3 0.5 = 0.831 ± 0.020 . Adding the cluster data reduces the uncertainty on this quantity by a factor of 1.4, which is unchanged whether the 3.1σ CMB-cluster lensing measurement is included or not. We then forecast the impact of CMB-cluster lensing measurements with future cluster catalogs. Adding CMB-cluster lensing measurements to the SZ cluster catalog of the ongoing SPT-3G survey is expected to improve the expected constraint on the dark energy equation of state w by a factor of 1.3 to σ(w) = 0.19. We find the largest improvements from CMB-cluster lensing measurements to be for σ 8, where adding CMB-cluster lensing data to the cluster number counts reduces the expected uncertainty on σ 8 by respective factors of 2.4 and 3.6 for SPT-3G and CMB-S4.
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ItemCMB/kSZ and Compton-y Maps from 2500 deg(2) of SPT-SZ and Planck Survey Data(American Astronomical Society, 2022-02-03)We present component-separated maps of the primary cosmic microwave background/kinematic Sunyaev–Zel'dovich (SZ) amplitude and the thermal SZ Compton-y parameter, created using data from the South Pole Telescope (SPT) and the Planck satellite. These maps, which cover the a1/42500 deg2 of the southern sky imaged by the SPT-SZ survey, represent a significant improvement over previous such products available in this region by virtue of their higher angular resolution ( 1.′25 for our highest-resolution Compton-y maps) and lower noise at small angular scales. In this work we detail the construction of these maps using linear combination techniques, including our method for limiting the correlation of our lowest-noise Compton-y map products with the cosmic infrared background. We perform a range of validation tests on these data products to test our sky modeling and combination algorithms, and we find good performance in all of these tests. Recognizing the potential utility of these data products for a wide range of astrophysical and cosmological analyses, including studies of the gas properties of galaxies, groups, and clusters, we make these products publicly available at http://pole.uchicago.edu/public/data/sptsz_ymap and on the NASA/LAMBDA website.