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Developing a unified pipeline for large-scale structure data analysis with angular power spectra -- I. The importance of redshift-space distortions for galaxy number counts

Monthly Notices of the Royal Astronomical Society, Volume 489, Issue 3, November 2019, Pages 3385–3402

Authors:

Konstantinos Tanidis, Stefano Camera

Abstract:

We develop a cosmological parameter estimation code for (tomographic) angular power spectra analyses of galaxy number counts, for which we include, for the first time, redshift-space distortions (RSDs) in the Limber approximation. This allows for a speed-up in computation time, and we emphasize that only angular scales where the Limber approximation is valid are included in our analysis. Our main result shows that a correct modelling of RSD is crucial not to bias cosmological parameter estimation. This happens not only for spectroscopy-detected galaxies, but even in the case of galaxy surveys with photometric redshift estimates. Moreover, a correct implementation of RSD is especially valuable in alleviating the degeneracy between the amplitude of the underlying matter power spectrum and the galaxy bias. We argue that our findings are particularly relevant for present and planned observational campaigns, such as the Euclid satellite or the Square Kilometre Array, which aim at studying the cosmic large-scale structure and trace its growth over a wide range of redshifts and scales.
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Author Correction: Time-lapse imagery and volunteer classifications from the Zooniverse Penguin Watch project.

Scientific data (2019)

Authors:

FM Jones, C Allen, C Arteta, J Arthur, C Black, LM Emmerson, R Freeman, G Hines, CJ Lintott, Z Macháčková, G Miller, R Simpson, C Southwell, HR Torsey, ANDREW Zisserman, TOM Hart

Abstract:

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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HORIZON-AGN virtual observatory – 2. Template-free estimates of galaxy properties from colours

Monthly Notices of the Royal Astronomical Society Oxford University Press 489:4 (2019) 4817-4835

Authors:

I Davidzon, C Laigle, PL Capak, O Ilbert, DC Masters, S Hemmati, N Apostolakos, J Coupon, SDL Torre, Julien Devriendt, Y Dubois, D Kashino, S Paltani, C Pichon

Abstract:

Using the HORIZON-AGN hydrodynamical simulation and self-organizing maps (SOMs), we show how to compress the complex, high-dimensional data structure of a simulation into a 2D grid, which greatly facilitates the analysis of how galaxy observables are connected to intrinsic properties. We first verify the tight correlation between the observed 0.3–5 μm broad-band colours of HORIZON-AGN galaxies and their high-resolution spectra. The correlation is found to extend to physical properties such as redshift, stellar mass, and star formation rate (SFR). This direct mapping from colour to physical parameter space still works after including photometric uncertainties that mimic the COSMOS survey. We then label the SOM grid with a simulated calibration sample to estimate redshift and SFR for COSMOS-like galaxies up to z ∼ 3. In comparison to state-of-the-art techniques based on synthetic templates, our method is comparable in performance but less biased at estimating redshifts, and significantly better at predicting SFRs. In particular, our ‘data-driven’ approach, in contrast to model libraries, intrinsically allows for the complexity of galaxy formation and can handle sample biases. We advocate that observations to calibrate this method should be one of the goals of next-generation galaxy surveys.

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Secularly powered outflows from AGN: the dominance of non-merger driven supermassive black hole growth

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2019)

Authors:

RJ Smethurst, BD Simmons, CJ Lintott, J Shanahan

Abstract:

Abstract Recent observations and simulations have revealed the dominance of secular processes over mergers in driving the growth of both supermassive black holes (SMBH) and galaxy evolution. Here we obtain narrowband imaging of AGN powered outflows in a sample of 12 galaxies with disk-dominated morphologies, whose history is assumed to be merger-free. We detect outflows in 10/12 sources in narrow band imaging of the $\mathrm{\left[ O \small {III}\right] }$ $5007~\mathring{\rm A}$ emission using filters on the Shane-3m telescope. We calculate a mean outflow rate for these AGN of $0.95\pm 0.14~\rm {M}_{\odot }~\rm {yr}^{-1}$. This exceeds the mean accretion rate of their SMBHs ($0.054\pm 0.039~\rm {M}_{\odot }~\rm {yr}^{-1}$) by a factor of ∼18. Assuming that the galaxy must provide at least enough material to power both the AGN and the outflow, this gives a lower limit on the average inflow rate of $\sim 1.01\pm 0.14~\rm {M}_{\odot }~\rm {yr}^{-1}$, a rate which simulations show can be achieved by bars, spiral arms and cold accretion. We compare our disk dominated sample to a sample of nearby AGN with merger dominated histories and show that the black hole accretion rates in our sample are 5 times higher (4.2σ) and the outflow rates are 5 times lower ( 2.6σ). We suggest that this could be a result of the geometry of the smooth, planar inflow in a secular dominated system, which is both spinning up the black hole to increase accretion efficiency and less affected by feedback from the outflow, than in a merger-driven system with chaotic quasi-spherical inflows. This work provides further evidence that secular processes are sufficient to fuel SMBH growth.
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A Space Mission to Map the Entire Observable Universe using the CMB as a Backlight

(2019)

Authors:

Kaustuv Basu, Mathieu Remazeilles, Jean-Baptiste Melin, David Alonso, James G Bartlett, Nicholas Battaglia, Jens Chluba, Eugene Churazov, Jacques Delabrouille, Jens Erler, Simone Ferraro, Carlos Hernández-Monteagudo, J Colin Hill, Selim C Hotinli, Ildar Khabibullin, Mathew Madhavacheril, Tony Mroczkowski, Daisuke Nagai, Srinivasan Raghunathan, Jose Alberto Rubino Martin, Jack Sayers, Douglas Scott, Naonori Sugiyama, Rashid Sunyaev, Íñigo Zubeldia
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