HECAP

Europe/Rome 2019-09-24 14:30:00 2019-09-24 15:30:00 IFPU Colloquium: Chandra, HST, and Radio Observations of Clusters of Galaxies Abstract. Clusters of galaxies are the most massive gravitationally bound objects in the Universe. While most of their mass is Dark Matter, the primary component of their visible matter is hot X-ray gas. A significant fraction of clusters are still growing through the infall of groups of galaxies or through the mergers of clusters. These cluster mergers are the most energetic events in the present Universe, after the Big Bang, releasing energies up to 10^64 ergs. Cluster mergers leave distinct signatures on the intracluster medium in the form of shocked gas and diffuse radio sources, relics. Most of the gravitational energy released during the merger is converted into shocks and gas turbulence in the cluster gas. This talk will highlight Chandra X-ray and radio results on the HST Frontier Fields clusters MACSJ017.5+3745, MACSJ1149.6+2223, and A2744, which are undergoing major mergers. Recent results on the merger of the A3411 and A3412 clusters show strong evidence for the electron re-acceleration at the merger site. Finally this talk will highlight results from the HST RELICS (Reionization Lensing Cluster Survey) which has led to the detection of very high redshift (z~10) galaxies which are strongly lensed by foreground clusters. ICTP ICTP pio@ictp.it 24 Sep 2019

Europe/Rome 2019-09-24 16:00:00 2019-09-24 17:00:00 IFPU Colloquium: Supermassive Black Holes (SMBH) at Work: The Effects of SMBH Outbursts on theEvolution of Gas Rich Galaxies, Groups, and Galaxy Clusters Abstract. Supermassive black holes (SMBHs) play key roles in galaxy and cluster evolution. This is most clearly seen in the “fossil record” that is imprinted in the gas rich atmospheres of early type galaxies, groups, and clusters by powerful SMBH outbursts. I will discuss the outburst history of M87 as chronicled in its radio and X-ray images and the implications of these outbursts for heating gas rich environments. Based on a simple shock model of M87’s 12 Myr old outburst, I will present the properties of the outburst including its age, total energy, and duration. In addition to discussing the outburst around M87, I will review the results of a galaxy survey that shows the effects of SMBH feedback on early type galaxies and has interesting implications for the growth of SMBHs over cosmic time. I conclude by describing a future X-ray mission, Lynx, whose sub-arcsecond angular resolution would allow us to study the evolution of SMBHs and hot, X-ray emitting atmospheres from high redshifts to the present. ICTP ICTP pio@ictp.it 24 Sep 2019

Europe/Rome 2019-09-26 14:30:00 2019-09-26 16:00:00 Status of Soft Theorem in D=4 (Its classical limit and understanding as Ward identity) Abstract. In recent years we explored the understanding of the soft factorization property of the S-matrix for a theory containing massless particles(photon/graviton) when the energy of external massless particles are small (soft particles). Though the leading factorization is discovered long ago (1965) by Weinberg, it's understanding in the subleading order (for all loop order in S-matrix) was not much explored prior to our (with Sen) work due to the infrared divergence of S-matrix in D=4. For loop corrected S-matrix, we found that the subleading soft factorization contains terms logarithmic in soft energy. The classical limit of this logarithmic terms in soft graviton theorem provides a new classical tail memory with the known permanent shift between the mirrors of gravitational wave detector. Currently, we are trying to understand whether this soft expansion can be understood as the Ward identity of any asymptotic symmetry. ICTP ICTP pio@ictp.it 26 Sep 2019

Europe/Rome 2019-10-01 14:30:00 2019-10-01 16:00:00 Primordial Features in the BAO spectrum Abstract. One of the main challenges in cosmology is to characterise the physics of inflation. While a single weakly-coupled scalar field rolling down a very flat potential satisfies the basic requirements that observations impose on an inflationary scenario, a great number of phenomena that could take place during inflation are still unconstrained by data. Primordial features are one example of this phenomena and a well-motivated proof of the early universe in their own right. In this talk, we demonstrate that features in primordial spectra, much like the standard BAO themselves, are immune to the most basic nonlinear processes of the late universe and can be tested with the full statistical power of LSS surveys. We perform a full fledged analysis of the BOSS survey data and put constraints on linearly and logarithmically spaced primordial oscillations which are competitive with the ones obtained from CMB observations. Furthermore, we provide an extensive forecast of future surveys, such as EUCLID, DESI and SPHEREx, showing that the future of constraining primordial features is indeed in LSS observations. ICTP ICTP pio@ictp.it 1 Oct 2019

Europe/Rome 2019-09-15 08:00:00 2019-09-22 22:00:00 Tenth Crete Regional Meeting in String Theory | (smr 3494) Kolymbari - Greece ICTP pio@ictp.it 15 Sep 2019 - 22 Sep 2019

Europe/Rome 2019-10-14 08:00:00 2019-10-16 22:00:00 Challenges and Opportunities of High Frequency Gravitational Wave Detection | (smr 3493) Most of what we know so far about the origin and evolution of the Universe is based on the information carried by electromagnetic radiation received from distant objects or composing the CMB. The recent direct detections of Gravitational Waves (GWs) have opened a new window of observation for phenomena in which gravity, instead of light, is the messenger. A few black hole and neutron star mergers have been reported and a plethora of new events are expected to be detected in the near-to-mid future. Many possible sources, especially related to the physics of the early Universe, produce (stochastic backgrounds of) GWs with a characteristic frequency much larger than the LIGO frequency range. The detection of high frequency GWs (HFGWs) is however very challenging, and only a few proposals have been made so far. The goal of this workshop is an open-minded discussion on the experimental and theoretical prospects of HFGWs. What are the possible sources and how well are they theoretically understood? What are the challenges faced in experimental setups and what are possible ideas to go beyond current technology? What can we learn about our Universe within the expected sensitivity of these proposals in the next decade? Our goal is to tackle these open questions by gathering a selected sample of people who are interested in these questions both from the theoretical and the experimental points of view. A few dedicated talks aim at introducing the key aspects and questions and bridging the gap between the different communities, while leaving ample time for discussions. Topics:   High Frequency Gravitational Waves Early Universe Cosmology High energy phase transitions Non-perturbative phenomena Interferometers Acoustic Cavities Optically levitated Sensors Speakers include: Odylio D. Aguiar (Instituto Nacional de Pesquisas Espaciais - INPE) Andreas Bauswein (GSI Darmstadt) Mike Cruise (University of Birmingham) Daniel Figueroa (Instituto de Física Corpuscular - IFIC) Andrew Geraci (Northwestern University) Maxim Goryachev (University of Western Australia) Hartmut Grote (Cardiff University) Mark Hindmarsh (University of Sussex) David Ottaway (University of Adelaide) Marco Peloso (University of Padova)   There is no registration fee for this activity. ICTP ICTP pio@ictp.it 14 Oct 2019 - 16 Oct 2019