Organizers: Alexie Leauthaud, Silvia Galli, Hendrik Hildebrandt, Julien Lesgourgues, Fabio Finelli, Bhuvnesh Jain

This summer online webinar series will explore the consistency of current constraints on the growth of structure and theoretical explanations for tentative differences between low and high redshift probes. We will cover 6 different topics with a 1.5h webinar each week. Webinars will include one review talk (25 min), two invited talks (20 min), and moderated community discussion. This format is an attempt, on behalf of the organizers, to enable a community overview and discussion of this topic during the COVID-19 era, while minimizing zoom fatigue. You only need to register once to attend webinars. Webinars begin on Wednesday June 2nd at 8:30 am Pacific (5:30 pm CEST) and will continue for 6 weeks at the same day/time. Webinars will be recorded and the recording will be posted here each week. Image credit: Benedikt Diemer.

Webinar registration link:

https://ucsc.zoom.us/webinar/register/WN_qB-yjwGWSE2k-Fkuc8xdFQ

1. CMB 

A common question during this session was how much the CMB constraints on S8 would improve. Silvia Galli calculated that with Planck+SPT3G (TTTEEE+CMB lensing) constraints should improve by a factor of 2 compared to the Planck only constraint. Simons Observatory and S4 give a similar number.

The recording of the CMB session is now available.

Santa Cruz, USA  Wed, Jun 2, 2021 at 8:30 am PDT / New York, USA ,Wed, Jun 2, 2021 at 11:30 am EDT  /  Paris, France, Wed, Jun 2, 2021 at 5:30 pm CEST / Munich, Germany, Wed, Jun 2, 2021 at 5:30 pm CEST / Sydney, Australia  Thu, Jun 3, 2021 at 1:30 am AEST / Tokyo, Japan  Thu, Jun 3, 2021 at 12:30 am JST

Key questions:

  • Are different CMB experiments consistent on measurements of the growth of structure, e.g. sigma8/S8?
  • Are primary CMB anisotropy measurements consistent with those estimated from CMB lensing?
  • Are there systematics that could impact the CMB measurements of sigma8/S8?
  • Is the sigma8 tension related to the CMB lensing puzzle and the AL parameter?
  • Is the CMB consistent across the sky and radial scales? Is there any connection between this problem and CMB anomalies?
  • How will the constraints on sigma8/S8 improve with upcoming CMB experiments?

Moderators: Silvia Galli and Fabio Finelli

Speakers: Antony Lewis (review talk, 25 min), Lennart Balkenhol (20 min), Steve Choi (20 min)

The videos from Antonys talk can be found here:

 The notebook with Python for making the plots can be found at this link.

And the recording of Antonys talk can also be seen here.

2. Clusters

The recording of the cluster session is now available.

Santa Cruz, USA, Wed, Jun 9, 2021 at 8:30 am PDT / New York, USA, Wed, Jun 9, 2021 at 11:30 am EDT / Paris, France, Wed, Jun 9, 2021 at 5:30 pm CEST  / Munich, Germany, Wed, Jun 9, 2021 at 5:30 pm CEST / Sydney, Australia, Thu, Jun 10, 2021 at 1:30 am AEST / Tokyo, Japan , Thu, Jun 10, 2021 at 12:30 am JST 

Key questions:

  • Overcoming systematic effects in cluster selections
  •  How can we best leverage X-ray, SZ, and optical data for cluster cosmology?
  • What is the role of clusters in the era of LSST/Euclid/Wfirst?
  • What is the current limit on mass calibration. If the ~2sigma tension that we have today is true, what mass calibration do we need to achieve to have a smoking gun (5sigma) signal?
  • Why is the lensing signal of low-richness clusters low, and can we fix it? Is this related to the “lensing is low” seen in lensing+clustering?

Moderators: Anja von der Linden and Eduardo Rozo

Speakers:  Gus Evrard (review talk, 25 min), Lindsay Bleem (20 min), Matteo Costanzi (20 min)

RSD => The RSD session is moved to JULY 14th

4. Cosmic Shear 

The recording for the Cosmic Shear session is now available.

Santa Cruz, USA, Wed, Jun 23, 2021 at 8:30 am PDT / New York, USA, Wed, Jun 23, 2021 at 11:30 am EDT / Paris, France, Wed, Jun 23, 2021 at 5:30 pm CEST / Munich, Germany, Wed, Jun 23, 2021 at 5:30 pm CEST / Sydney, Australia, Thu, Jun 24, 2021 at 1:30 am AEST / Tokyo, Japan, Thu, Jun 24, 2021 at 12:30 am JST

Key questions:

  • Are there systematics that could explain the offset with respect to Planck?
  • What about photo-z? 
  • How significant can this become, given the error on S8 from Planck? 
  • Things that are common between analyses, and things that are different
  • Priorities for the next few years
  • What about the look-elsewhere effect? How to quantify the tension in high dimensional space?

Moderators: Hendrik Hildebrandt and Bhuvnesh Jain

Speakers: Chihway Chang (review talk, 25 min), Alexandra Amon (20 min), Marika Asgari (20 min)

5. Lensing + Clustering

The recording for the Lensing+Clustering session is now available.

Santa Cruz, USA, Wed, Jun 30, 2021 at 8:30 am PDT / New York, USA , Wed, Jun 30, 2021 at 11:30 am EDT  / Paris, France , Wed, Jun 30, 2021 at 5:30 pm CEST  / Munich, Germany, Wed, Jun 30, 2021 at 5:30 pm CEST / Sydney, Australia, Thu, Jul 1, 2021 at 1:30 am AEST / Tokyo, Japan, Thu, Jul 1, 2021 at 12:30 am JST

Key questions:

  • What are the key systematics impacting joint analyses of lensing and clustering?
  • What is the halo mass and scale dependance of the lensing is low effect?
  • Are there lensing systematics that could explain the lensing is low effect?
  • Is the lensing is low effect related to the low lensing signal around low richness clusters in DES?
  • What about the look-elsewhere effect? How to quantify the tension in high dimensional space?
  • Is there extra cosmological information to be had by analyzing non-linear scales after marginalizing over the necessary galaxy formation physics?
  • What is the optimal way to combine projected clustering and lensing with redshift space measurements?
  • How useful will higher order statistics be in boosting constraining power without a proliferation of additional nuisance parameters? 

Moderators: Alexie Leauthaud and Joe de Rose

Speakers: Johannes Lange (review talk, 25 min), Sukhdeep Singh (20 min), Tilman Troester (20 min)

6. Theory

The recording of the theory session is now available.

Santa Cruz, USA, Wed, Jul 7, 2021 at 8:30 am PDT  /  New York, USA , Wed, Jul 7, 2021 at 11:30 am EDT / Paris, France, Wed, Jul 7, 2021 at 5:30 pm CEST  / Munich, Germany, Wed, Jul 7, 2021 at 5:30 pm CEST / Sydney, Australia, Thu, Jul 8, 2021 at 1:30 am AEST  / Tokyo, Japan, Thu, Jul 8, 2021 at 12:30 am JST  

Key questions:

  • What models could explain a low value of S8?
  • Are there theory models that can explain both S8 and H0?
  • What data used tests would be most useful to inform models?

Moderators: Fabio Finelli and Julien Lesgourgues

Speakers: Vivian Poulin (review talk, 25 min), Maria Archidiacono (20 min), Mario Ballardini (20 min)

7. Redshift Space Distortions

The recording for the RSD session is now available.

Santa Cruz, USA Wed, Jul 14, 2021 at 8:30 am PDT / New York, USA Wed, Jul 14, 2021 at 11:30 am EDT / Paris, France Wed, Jul 14, 2021 at 5:30 pm CEST /Munich, Germany Wed, Jul 14, 2021 at 5:30 pm CEST / Sydney, Australia Thu, Jul 15, 2021 at 1:30 am AEST / Tokyo, Japan Thu, Jul 15, 2021 at 12:30 am JST

Key questions:

  • Are RSD constraints consistent with Planck?
  • Are there differences between small and large scales RSD?
  • What are the key systematics?
  • What are the major modeling challenges?

Moderators: Martin White and Alexie Leauthaud

Speakers:  Will Percival (review talk, 25 min), Johannes Lange (20 min), Mikhail Ivanov (20 min)