Disentangling magnification in combined shear-clustering analyses

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 491 (2020) 1746-1758

L Thiele, CAJ Duncan, D Alonso

<jats:title>ABSTRACT</jats:title> <jats:p>We investigate the sensitivity to the effects of lensing magnification on large-scale structure analyses combining photometric cosmic shear and galaxy clustering data (i.e. the now commonly called ‘3 × 2-point’ analysis). Using a Fisher matrix bias formalism, we disentangle the contribution to the bias on cosmological parameters caused by ignoring the effects of magnification in a theory fit from individual elements in the data vector, for Stage-III and Stage-IV surveys. We show that the removal of elements of the data vectors that are dominated by magnification does not guarantee a reduction in the cosmological bias due to the magnification signal, but can instead increase the sensitivity to magnification. We find that the most sensitive elements of the data vector come from the shear-clustering cross-correlations, particularly between the highest redshift shear bin and any lower redshift lens sample, and that the parameters ΩM, $S_8=\sigma _8\sqrt{\Omega _\mathrm{ M}/0.3}$, and w0 show the most significant biases for both survey models. Our forecasts predict that current analyses are not significantly biased by magnification, but this bias will become highly significant with the continued increase of statistical power in the near future. We therefore conclude that future surveys should measure and model the magnification as part of their flagship ‘3 × 2-point’ analysis.</jats:p>

KROSS-SAMI: a direct IFS comparison of the Tully-Fisher relation across 8 Gyr since z approximate to 1


AL Tiley, M Bureau, L Cortese, CM Harrison, HL Johnson, JP Stott, AM Swinbank, I Smail, D Sobral, AJ Bunker, K Glazebrook, RG Bower, D Obreschkow, JJ Bryant, MJ Jarvis, J Bland-Hawthorn, G Magdis, AM Medling, SM Sweet, C Tonini, OJ Turner, RM Sharples, SM Croom, M Goodwin, IS Konstantopoulos, NPF Lorente, JS Lawrence, J Mould, MS Owers, SN Richards

The energetics of starburst-driven outflows at z similar to 1 from KMOS


AM Swinbank, CM Harrison, AL Tiley, HL Johnson, I Smail, JP Stott, PN Best, RG Bower, M Bureau, A Bunker, M Cirasuolo, M Jarvis, GE Magdis, RM Sharples, D Sobral

LoTSS DR1: Double-double radio galaxies in the HETDEX field


VH Mahatma, MJ Hardcastle, WL Williams, PN Best, JH Croston, K Duncan, B Mingo, R Morganti, M Brienza, RK Cochrane, G Gurkan, JJ Harwood, MJ Jarvis, M Jamrozy, N Jurlin, LK Morabito, HJA Rottgering, J Sabater, TW Shimwell, DJB Smith, A Shulevski, C Tasse

Black hole - Galaxy correlations in simba


N Thomas, R Dave, D Angles-Alcazar, M Jarvis

The fourth data release of the Kilo-Degree Survey: Ugri imaging and nine-band optical-IR photometry over 1000 square degrees

Astronomy and Astrophysics 625 (2019)

K Kuijken, C Heymans, A Dvornik, H Hildebrandt, JTA De Jong, AH Wright, T Erben, M Bilicki, B Giblin, HY Shan, F Getman, A Grado, H Hoekstra, L Miller, N Napolitano, M Paolilo, M Radovich, P Schneider, W Sutherland, M Tewes, C Tortora, EA Valentijn, GA Verdoes Kleijn

© ESO 2019. Context. The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope, specifically designed for measuring weak gravitational lensing by galaxies and large-scale structure. When completed it will consist of 1350 square degrees imaged in four filters (ugri). Aims. Here we present the fourth public data release which more than doubles the area of sky covered by data release 3. We also include aperture-matched ZYJHKs photometry from our partner VIKING survey on the VISTA telescope in the photometry catalogue. We illustrate the data quality and describe the catalogue content. Methods. Two dedicated pipelines are used for the production of the optical data. The ASTRO-WISE information system is used for the production of co-added images in the four survey bands, while a separate reduction of the r-band images using the THELI pipeline is used to provide a source catalogue suitable for the core weak lensing science case. All data have been re-reduced for this data release using the latest versions of the pipelines. The VIKING photometry is obtained as forced photometry on the THELI sources, using a re-reduction of the VIKING data that starts from the VISTA pawprints. Modifications to the pipelines with respect to earlier releases are described in detail. The photometry is calibrated to the Gaia DR2 G band using stellar locus regression. Results. In this data release a total of 1006 square-degree survey tiles with stacked ugri images are made available, accompanied by weight maps, masks, and single-band source lists. We also provide a multi-band catalogue based on r-band detections, including homogenized photometry and photometric redshifts, for the whole dataset. Mean limiting magnitudes (5σ in a 2″ aperture) and the tile-to-tile rms scatter are 24.23? ±? 0.12, 25.12? ±? 0.14, 25.02? ±? 0.13, 23.68? ±? 0.27 in ugri, respectively, and the mean r-band seeing is 0.″70.

Radio-loud AGN in the first LoTSS data release The lifetimes and environmental impact of jet-driven sources


MJ Hardcastle, WL Williams, PN Best, JH Croston, KJ Duncan, HJA Rottgering, J Sabater, TW Shimwell, C Tasse, JR Callingham, RK Cochrane, F de Gasperin, G Gurkan, MJ Jarvis, V Mahatma, GK Miley, B Mingo, S Mooney, LK Morabito, SP O'Sullivan, I Prandoni, A Shulevski, DJB Smith

Simulating and interpreting deep observations in the Hubble Ultra Deep Field with the JWST/NIRSpec low-resolution ‘prism’

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 483 (2019) 2621-2640

J Chevallard, E Curtis-Lake, S Charlot, P Ferruit, G Giardino, M Franx, MV Maseda, R Amorin, S Arribas, A Bunker, S Carniani, B Husemann, P Jakobsen, R Maiolino, J Pforr, TD Rawle, H-W Rix, R Smit, CJ Willott

Using Sparse Gaussian Processes for Predicting Robust Inertial Confinement Fusion Implosion Yields

IEEE Transactions on Plasma Science Institute of Electrical and Electronics Engineers (IEEE) (2019) 1-8

P Hatfield, S Rose, R Scott, I Almosallam, S Roberts, M Jarvis

Comparing galaxy clustering in Horizon-AGN simulated light-cone mocks and VIDEO observations


PW Hatfield, C Laigle, MJ Jarvis, J Devriendt, I Davidzon, O Ilbert, C Pichon, Y Dubois

LoTSS DR1: Double-double radio galaxies in the HETDEX field

Astronomy and Astrophysics 622 (2019)

VH Mahatma, MJ Hardcastle, WL Williams, PN Best, JH Croston, K Duncan, B Mingo, R Morganti, M Brienza, RK Cochrane, G Gürkan, JJ Harwood, MJ Jarvis, M Jamrozy, N Jurlin, LK Morabito, HJA Röttgering, J Sabater, TW Shimwell, DJB Smith, A Shulevski, C Tasse

© ESO 2019. Context. Double-double radio galaxies (DDRGs) represent a short but unique phase in the life-cycle of some of the most powerful radio-loud active galactic nuclei (RLAGN). These galaxies display large-scale remnant radio plasma in the intergalactic medium left behind by a past episode of active galactic nuclei (AGN) activity, and meanwhile, the radio jets have restarted in a new episode. The knowledge of what causes the jets to switch off and restart is crucial to our understanding of galaxy evolution, while it is important to know if DDRGs form a host galaxy dichotomy relative to RLAGN. Aims. The sensitivity and field of view of LOFAR enables the observation of DDRGs on a population basis rather than single-source observations. Using statistical comparisons with a control sample of RLAGN, we may obtain insights into the nature of DDRGs in the context of their host galaxies, where physical differences in their hosts compared to RLAGN as a population may allow us to infer the conditions that drive restarting jets. Methods. We utilised the LOFAR Two-Metre Sky Survey (LoTSS) DR1, using a visual identification method to compile a sample of morphologically selected candidate DDRGs, showing two pairs of radio lobes. To confirm the restarted nature in each of the candidate sources, we obtained follow-up observations with the Karl. G. Jansky Very Large Array (VLA) at higher resolution to observe the inner lobes or restarted jets, the confirmation of which created a robust sample of 33 DDRGs. We created a comparison sample of 777 RLAGN, matching the luminosity distribution of the DDRG sample, and compared the optical and infrared magnitudes and colours of their host galaxies. Results. We find that there is no statistically significant difference in the brightness of the host galaxies between double-doubles and single-cycle RLAGN. The DDRG and RLAGN samples also have similar distributions in WISE mid-infrared colours, indicating similar ages of stellar populations and dust levels in the hosts of DDRGs. We conclude that DDRGs and "normal" RLAGN are hosted by galaxies of the same type, and that DDRG activity is simply a normal part of the life cycle of RLAGN. Restarted jets, particularly for the class of low-excitation radio galaxies, rather than being a product of a particular event in the life of a host galaxy, must instead be caused by smaller scale changes, such as in the accretion system surrounding the black hole.

LOFAR observations of the XMM-LSS field


CL Hale, W Williams, MJ Jarvis, MJ Hardcastle, LK Morabito, TW Shimwell, C Tasse, PN Best, JJ Harwood, I Heywood, I Prandoni, HJA Rottgering, J Sabater, DJB Smith, RJ van Weeren

The LOFAR Two-metre Sky Survey IV. First Data Release: Photometric redshifts and rest-frame magnitudes


KJ Duncan, J Sabater, HJA Rottgering, MJ Jarvis, DJB Smith, PN Best, JR Callingham, R Cochrane, JH Croston, MJ Hardcastle, B Mingo, L Morabito, D Nisbet, I Prandoni, TW Shimwell, C Tasse, GJ White, WL Williams, L Alegre, KT Chyzy, G Gurkan, M Hoeft, R Kondapally, AP Mechev, GK Miley, DJ Schwarz, RJ van Weeren

The LOFAR Two-metre Sky Survey II. First data release


TW Shimwell, C Tasse, MJ Hardcastle, AP Mechev, WL Williams, PN Best, HJA Rottgering, JR Callingham, TJ Dijkema, F de Gasperin, DN Hoang, B Hugo, M Mirmont, JBR Oonk, I Prandoni, D Rafferty, J Sabater, O Smirnov, RJ van Weeren, GJ White, M Atemkeng, L Bester, E Bonnassieux, M Bruggen, G Brunetti, KT Chyzy, R Cochrane, JE Conway, JH Croston, A Danezi, K Duncan, M Haverkorn, GH Heald, M Iacobelli, HT Intema, N Jackson, M Jamrozy, MJ Jarvis, R Lakhoo, M Mevius, GK Miley, L Morabito, R Morganti, D Nisbet, E Orru, S Perkins, RF Pizzo, C Schrijvers, DJB Smith, R Vermeulen, MW Wise, L Alegre, DJ Bacon, IM van Bemmel, RJ Beswick, A Bonafede, A Botteon, S Bourke, M Brienza, GC Rivera, R Cassano, AO Clarke, CJ Conselice, RJ Dettmar, A Drabent, C Dumba, KL Emig, TA Ensslin, C Ferrari, MA Garrett, RT Genova-Santos, A Goyal, G Gurkan, C Hale, JJ Harwood, V Heesen, M Hoeft, C Horellou, C Jackson, G Kokotanekov, R Kondapally, M Kunert-Bajraszewska, V Mahatma, EK Mahony, S Mandal, JP McKean, A Merloni, B Mingo, A Miskolczi, S Mooney, B Nikiel-Wroczynski, SP O'Sullivan, J Quinn, W Reich, C Roskowinski, A Rowlinson, F Savini, A Saxena, DJ Schwarz, A Shulevski, SS Sridhar, HR Stacey, S Urquhart, MHD van der Wiel, E Varenius, B Webster, A Wilber

A new sample of southern radio galaxies: host-galaxy masses and star-formation rates


T Marubini, MJ Jarvis, S Fine, T Mauch, K McAlpine, M Prescott

Radio source extraction with PROFOUND


CL Hale, ASG Robotham, LJM Davies, MJ Jarvis, SP Driver, I Heywood

Consistent cosmic shear in the face of systematics: A B -mode analysis of KiDS-450, DES-SV and CFHTLenS

Astronomy and Astrophysics 624 (2019)

M Asgari, C Heymans, H Hildebrandt, L Miller, P Schneider, A Amon, A Choi, T Erben, C Georgiou, J Harnois-Deraps, K Kuijken

© ESO 2019. We analyse three public cosmic shear surveys; the Kilo-Degree Survey (KiDS-450), the Dark Energy Survey (DES-SV) and the Canada France Hawaii Telescope Lensing Survey (CFHTLenS). Adopting the "COSEBIs" statistic to cleanly and completely separate the lensing E-modes from the non-lensing B-modes, we detect B-modes in KiDS-450 and CFHTLenS at the level of ∼2.7σ. For DES-SV we detect B-modes at the level of 2.8σ in a non-tomographic analysis, increasing to a 5.5σB-mode detection in a tomographic analysis. In order to understand the origin of these detected B-modes we measure the B-mode signature of a range of different simulated systematics including PSF leakage, random but correlated PSF modelling errors, camera-based additive shear bias and photometric redshift selection bias. We show that any correlation between photometric-noise and the relative orientation of the galaxy to the point-spread-function leads to an ellipticity selection bias in tomographic analyses. This work therefore introduces a new systematic for future lensing surveys to consider. We find that the B-modes in DES-SV appear similar to a superposition of the B-mode signatures from all of the systematics simulated. The KiDS-450 and CFHTLenS B-mode measurements show features that are consistent with a repeating additive shear bias.

Towards emulating cosmic shear data: revisiting the calibration of the shear measurements for the Kilo-Degree Survey

Astronomy and Astrophysics EDP Sciences 624 (2019) A92

H Hoekstra, L Miller, A Kannawadi, T Erben, AH Wright, M Viola, IF Conti, R Herbonnet, H Hildebrandt, C Heymans, K Kuijken, M Vakili

Exploiting the full statistical power of future cosmic shear surveys will necessitate improvements to the accuracy with which the gravitational lensing signal is measured. We present a framework for calibrating shear with image simulations that demonstrates the importance of including realistic correlations between galaxy morphology, size and more importantly, photometric redshifts. This realism is essential so that selection and shape measurement biases can be calibrated accurately for a tomographic cosmic shear analysis. We emulate Kilo-Degree Survey (KiDS) observations of the COSMOS field using morphological information from {\it Hubble} Space Telescope imaging, faithfully reproducing the measured galaxy properties from KiDS observations of the same field. We calibrate our shear measurements from lensfit, and find through a range of sensitivity tests that lensfit is robust and unbiased within the allowed 2 per cent tolerance of our study. Our results show that the calibration has to be performed by selecting the tomographic samples in the simulations, consistent with the actual cosmic shear analysis, because the joint distributions of galaxy properties are found to vary with redshift. Ignoring this redshift variation could result in misestimating the shear bias by an amount that exceeds the allowed tolerance. To improve the calibration for future cosmic shear analyses, it will be essential to also correctly account for the measurement of photometric redshifts, which requires simulating multi-band observations.

The Lockman Hole Project: new constraints on the sub-mJy source counts from a wide-area 1.4 GHz mosaic


I Prandoni, G Guglielmino, R Morganti, M Vaccari, A Maini, HJA Rottgering, MJ Jarvis, MA Garrett

A rapid occultation event in NGC 3227

Monthly Notices of the Royal Astronomical Society 481 (2018) 2470-2478

TJ Turner, JN Reeves, V Braito, A Lobban, S Kraemer, L Miller

© 2018 The Author(s). NGC 3227 exhibits rapid flux and spectral variability in the X-ray band. To understand this behaviour, we conducted a coordinated observing campaign using 320 ks of XMM- Newton exposures together with 160 ks of overlapping NuSTAR observations, spanning a month. Here, we present a rapid variability event that occurs toward the end of the campaign. The spectral hardening event is accompanied by a change in the depth of an unresolved transition array (UTA), whose time-dependent behaviour is resolved using the RGS data. This UTA fingerprint allows us to identify this as a transit event, where a clump of gas having NH ~ 5 × 1022 atoms cm-2, log Ξ ~ 2 occults ~ 60 per cent of the continuum photons over the course of approximately a day. This occulting gas is likely associated with clouds in the inner broad-line region. An additional zone of gas with lower column and higher ionization, matches the outflow velocity of the variable zone, and may represent transmission through the cloud limb.