Mon 22 Apr 13:00: The Dark Energy Spectroscopic Instrument (DESI) Year 1 Results: Baryon Acoustic Oscillations and implications for cosmology
DESI represents the culmination of multi-years efforts and advanced spectroscopic techniques. Placed at Mayall 4-meter Telescope, DESI harnesses the power of 5,000 robotic fiber positioners, coupled with state-of-the-art spectrographs, to capture the spectral signatures of millions of galaxies and quasars with unprecedented precision. DESI success is also based on the collaborative spirit of its community, more than 400 scientists over 72 institutions. This data release corresponds to the first year of observations; it holds immense scientific promise across a multitude of fronts: from constraining cosmological parameters, mapping the expansion history of the Universe, to the properties of dark energy and the properties of neutrinos. So far only Baryon Acoustic Oscillations (BAO) information has been fully analysed and made public. I will summarise the main findings and the implications for cosmology.
- Speaker: Licia Verde (University of Barcelona)
- Monday 22 April 2024, 13:00-14:00
- Venue: CMS, Pav. B, CTC Common Room (B1.19) [Potter Room].
- Series: Cosmology Lunch; organiser: Fiona McCarthy.
Fri 26 Apr 11:30: Title to be confirmed
Abstract not available
- Speaker: Ana Bonaca (Carnegie)
- Friday 26 April 2024, 11:30-12:30
- Venue: Ryle seminar room + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Fri 10 May 11:30: Title to be confirmed
Abstract not available
- Speaker: Rajsekhar Mohapatra (Princeton)
- Friday 10 May 2024, 11:30-12:30
- Venue: Ryle seminar room + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Mon 13 May 09:45: Which universes does the no-boundary wave function favour?
Please notice the unusual schedule (9:45am) and location (MR9) due to previous overlaps with the Dirac lunch and Dirac lecture.
- Speaker: Jean-Luc Lehners (MPI for Gravitational Physics, Potsdam)
- Monday 13 May 2024, 09:45-10:45
- Venue: CMS, Pav. B, MR9 (B0.09) .
- Series: Cosmology Lunch; organiser: Thomas Colas.
Mon 13 May 09:45: Which universes does the no-boundary wave function favour?
Please notice the unusual schedule due to previous overlaps with the Dirac lunch and Dirac lecture.
- Speaker: Jean-Luc Lehners (MPI for Gravitational Physics, Potsdam)
- Monday 13 May 2024, 09:45-10:45
- Venue: CMS, Pav. B, CTC Common Room (B1.19) [Potter Room].
- Series: Cosmology Lunch; organiser: Thomas Colas.
Tue 22 Oct 11:15: Studies of the reionization-era intergalactic and circumgalactic media using cosmological simulations
TBC
- Speaker: Dr. Caitlin Doughty (University of Leiden/MPA Garching)
- Tuesday 22 October 2024, 11:15-12:00
- Venue: Coffee area, Battcock Centre.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Tue 11 Jun 11:15: The ionising properties of galaxies at the Epoch of Reionisation with JWST
TBC
- Speaker: Dr. Charlotte Simmonds (Kavli Institute for Technology, University of Cambridge)
- Tuesday 11 June 2024, 11:15-12:00
- Venue: Coffee area, Battcock Centre.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Tue 28 May 11:15: The Black Hole Mass Metallicity Relation and Insights into Galaxy Quenching
TBC
- Speaker: William Baker (University of Cambridge)
- Tuesday 28 May 2024, 11:15-12:00
- Venue: Coffee area, Battcock Centre.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Tue 14 May 11:15: Liquid Crystal based adaptive optics
TBC
- Speaker: Oana Niculescu (University of Cambridge)
- Tuesday 14 May 2024, 11:15-12:00
- Venue: Coffee area, Battcock Centre.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Tue 07 May 11:15: Interferometric measurements of the 21-cm signal with SKA
The Cosmic Dawn marks the first star formations and preceded the Epoch-of-Reionization, when the Universe underwent a fundamental transformation propelled by the radiation from these first stars and galaxies. Interferometric 21-cm experiments aim to probe redshifted neutral hydrogen signals from these periods, constraining the conditions of the early Universe. The SKA -LOW instrument of the Square Kilometre Array telescope is envisaged to be the largest and most sensitive radio telescope at m and cm wavelengths. In this talk we present a data analysis pipeline that was used in the SKA Science Data Challenge 3a: Epoch of Reionisation (SKA SDC3a) to process the novel data products expected from the SKA . To determine whether a successful 21-cm detection is possible with the envisaged SKA , we implement predictive foreground and Bayesian Gaussian Process Regression models alongside a foreground avoidance strategy to isolate the 21-cm signal from that of the astrophysical radio frequency (RF) foregrounds.
- Speaker: Yuchen Liu and Oscar O'Hara (Cavendish Astrophysics)
- Tuesday 07 May 2024, 11:15-12:00
- Venue: Coffee area, Battcock Centre.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Tue 30 Apr 11:15: Radio observations of extra-galactic transients with the AMI-LA telescope
TBC
- Speaker: Dr. Lauren Rhodes (University of Oxford)
- Tuesday 30 April 2024, 11:15-12:00
- Venue: Coffee area, Battcock Centre.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Tue 30 Apr 13:00: Title to be confirmed
Abstract not available
- Speaker: Florian Lienhard (Zurich)
- Tuesday 30 April 2024, 13:00-14:00
- Venue: Battcock coffee area + ONLINE - Details to be sent by email.
- Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.
Tue 28 May 13:00: Title to be confirmed
Abstract not available
- Speaker: Nicolina Chrysaphi (Sorbonne)
- Tuesday 28 May 2024, 13:00-14:00
- Venue: Hoyle Committee Room + ONLINE - Details to be sent by email.
- Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.
Tue 21 May 13:00: Title to be confirmed
Abstract not available
- Speaker: Hamish Innes (Freie Universität - Berlin)
- Tuesday 21 May 2024, 13:00-14:00
- Venue: Hoyle Committee Room + ONLINE - Details to be sent by email.
- Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.
Tue 23 Apr 13:00: The physical mechanism of the streaming instability, and whether it works in vortices
A major hurdle in planet formation theory is that we do not understand how small pebbles congregate into big planetesimals. A promising way to overcome this metre-scale barrier involves a fluid dynamics phenomenon called the streaming instability (SI). It concentrates the pebbles into clumps that are dense enough to collapse gravitationally, thereby forming planetesimals.
Unfortunately, the mechanism responsible for the onset of the instability remains mysterious. This makes it hard to evaluate the robustness of the instability, or to understand how it saturates. It has recently been shown that the SI is a Resonant Drag Instability (RDI) involving inertial waves. In the first part of this talk, I build on this insight to produce a clear physical picture of how the SI develops.
Another problem is that the SI can only devellop in regions containing a high density of similar-sized pebbles. Those conditions are met in large-scale vortices, but no one knows if the SI can feed on vorticial flows. Indeed, any instability can only devellop in specific flows, and a priori the SI is tailored to Keplerian disc flows, not vortex flows. I answer this question in the second part of the talk. To do so, I develop a simple pen-and-paper model of a dust-laden vortex in a protoplanetary disc. I find that if the vortex is weak and anticyclonic, dust drifts towards its centre. I then build a vortex analog of the shearing box to analyse the local linear stability of my dusty vortex. I find that the dust’s drift powers an instability which closely resembles the SI. This result strengthens the case for vortex-induced planetesimal formation.
- Speaker: Nathan Magnan (DAMTP)
- Tuesday 23 April 2024, 13:00-14:00
- Venue: Hoyle Committee Room + ONLINE - Details to be sent by email.
- Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.
Thu 02 May 16:00: Experimental Studies of Black Holes: Status & Prospects
More than a century ago, Albert Einstein presented his general theory of gravitation. One of the predictions of this theory is that not only particles and objects with mass, but also the quanta of light, photons, are tied to the curvature of space-time, and thus to gravity. There must be a critical mass density, above which photons cannot escape. These are black holes. It took fifty years before possible candidate objects were identified by observational astronomy. Another fifty years have passed, until we finally can present detailed and credible experimental evidence that black holes of 10 to 10^10 times the mass of the Sun exist in the Universe. Three very different experimental techniques have enabled these critical experimental breakthroughs. It has become possible to investigate the space-time structure in the vicinity of the event horizons of black holes. I will summarize these interferometric techniques, and discuss the spectacular recent improvements achieved with all three techniques. In conclusion, I will sketch where the path of exploration and inquiry may lead to in the next decades.
- Speaker: Reinhard Genzel (Max Planck Institute for Extraterrestrial Physics)
- Thursday 02 May 2024, 16:00-17:00
- Venue: Hoyle Lecture Theatre, Institute of Astronomy (and online - details to be sent by e-mail).
- Series: The Kavli Lectures; organiser: Alison Wilson.
Fri 19 Apr 11:30: Probing the epoch of galaxy assembly with MUSE
Abstract not available
- Speaker: Trevor Mendel (ANU)
- Friday 19 April 2024, 11:30-12:30
- Venue: Ryle seminar room + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Fri 31 May 11:30: Title to be confirmed
Abstract not available
- Speaker: Sinan Deger (KICC)
- Friday 31 May 2024, 11:30-12:30
- Venue: Ryle seminar room + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Wed 22 May 11:30: Hierarchical star cluster assembly boosts intermediate-mass black hole formation
Observations and high-resolution hydrodynamical simulations indicate that massive star clusters assemble hierarchically from sub-clusters with a universal power-law cluster mass function. We study the consequences of such assembly for the formation of intermediate-mass black holes (IMBHs) and massive black hole (MBH) seeds at low metallicities (1% of the solar value) with our updated direct N-body code BIFROST in simulations up to N = 2.35 million stars. The GPU -accelerated code BIFROST is based on the hierarchical fourth-order forward integrator. Few-body systems are treated using secular and regularized techniques including post-Newtonian equations of motion up to order PN3 .5 and gravitational-wave recoil kicks for merging BHs. Stellar evolution is provided by the fast population synthesis code SEVN . IMBHs with masses up to 2200 solar masses form rapidly mainly via the collapse of very massive stars (VMSs) assembled through repeated collisions of massive stars followed by growth through tidal disruption events (TDEs) and BH mergers. Later the IMB Hs form subsystems resulting in gravitational-wave BH-BH, IMBH -BH and IMBH -IMBH mergers with a 1000 solar mass gravitational-wave detection being the observable prediction. Our simulations indicate that the hierarchical formation of massive star clusters in metal poor environments naturally results in formation of potential seeds for supermassive black holes.
- Speaker: Antti Rantala (MPA)
- Wednesday 22 May 2024, 11:30-12:30
- Venue: Martin Ryle Meeting Room, KICC + Online.
- Series: Kavli Institute for Cosmology Seminars; organiser: Alison Wilson.
Thu 16 May 16:00: Inside Astronomically Realistic Black Holes
I will use a real-time general relativistic Black Hole Flight Similator to show what really happens inside astronomically realistic black holes. The inner horizon of a rotating black hole is the most violent place in the Universe, easily reaching and surpassing energy densities attained in the Big Bang. What does Nature do at this extraordinary place?
- Speaker: Prof. Andrew Hamilton (University of Colorado Boulder)
- Thursday 16 May 2024, 16:00-17:00
- Venue: Hoyle Lecture Theatre, Institute of Astronomy.
- Series: Institute of Astronomy Colloquia; organiser: eb694.