Fri 30 May 11:30: Chasing the Light: Shadowing, Collimation, and the Rapid Growth of Infant Black Holes
Observations with the James Webb Space Telescope (JWST) have uncovered a substantial population of high-redshift broad-line active galactic nuclei (AGNs) characterized by moderate luminosities, weak X-ray emissions, and faint high-ionization lines, challenging conventional models of AGN activity. In this talk I will propose that these sources are accreting at super-Eddington rates, and discuss how such accretion flows, shaped by thick disk geometries and anisotropic radiation fields, may provide new insights into black hole growth in the early Universe.
- Speaker: Piero Madau (UCSC)
- Friday 30 May 2025, 11:30-12:30
- Venue: Ryle Seminar Room, KICC + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Fri 02 May 11:30: Exploring high-redshift quenched galaxies: from low-mass to massive
Abstract not available
- Speaker: William Baker (Dark)
- Friday 02 May 2025, 11:30-12:30
- Venue: Ryle Seminar Room, KICC + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Fri 16 May 11:30: Towards understanding the epoch of reionization out to the cosmic dawn
Work on understanding the epoch of reionization has been galvanized in recent years by a series of observational and theoretical breakthroughs. These include the recognition that spatial structure in the Lyman-α forest retains signatures of reionization history, the discovery of galaxies and quasars deep in the reionization era by JWST , and renewed efforts to detect the redshifted 21-cm signal from cosmic dawn and the epoch of reionization. In this talk, I will present a series of results from our group that address the goal of understanding the evolving ionization state of the Universe, from cosmic dawn to the final stages of reionization. This includes new simulations of reionization, updated measurements of the mean free path of ionizing photons, improved constraints on the neutral hydrogen fraction from quasar damping wings, and interpretations of AGNs and LAEs discovered by JWST . I will describe our ongoing attempts to directly detect the neutral parts of the IGM for the first time using the 21-cm forest, and discuss the implications of JWST data for quasar growth during this era. Deeper into the reionization epoch, I will present new approaches to charting reionization using LAEs. Closer to cosmic dawn, I will highlight new radiative transfer models of Lyman-α coupling and a model-agnostic framework for combining JWST and 21-cm observations, including results from REACH . I will conclude by reviewing where we are and outlining key challenges ahead.
- Speaker: Girish Kulkarni (TIFR)
- Friday 16 May 2025, 11:30-12:30
- Venue: Ryle Seminar Room, KICC + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Mon 28 Apr 13:00: String axions: the hot and the fuzzy
String axions have been proposed as candidates for solving several puzzles in cosmology. In this talk, I will focus on axions as dark matter. After reviewing how string axions can occur in our universe, I will provide a string theoretical explanation of dark matter as composed of axions coming from type IIB string theory. Based on the latest bounds, I will show how likely it is for dark matter to be composed of such particles and in which abundance, and I will provide predictions on the preferred ranges of masses and decay constants. On the contrary, requiring the axions to lie in a particular range of the parameter space imposes constraints on the UV theory. I will focus both on the role of moduli stabilization and the landscape of string vacua. Finally, I will discuss axion production at the end of inflation and the implications for the proposed cosmic axion background.
- Speaker: Nicole Righi (King's College London)
- Monday 28 April 2025, 13:00-14:00
- Venue: CMS, Pav. B, CTC Common Room (B1.19) [Potter Room].
- Series: Cosmology Lunch; organiser: Thomas Colas.
Wed 14 May 16:00: Spacetime Singularities and Black Holes
After a brief introduction to Einstein’s theory of general relativity and its most profound prediction of black holes, I will focus on spacetime singularities, i.e., regions where general relativity breaks down and must be replaced by a quantum theory of gravity. I first discuss singularities inside black holes. This is the usual case and is an old story, but there have been some recent developments. I will next describe some new results which show that some black holes have singularities on their surface. Finally, I will discuss the possibility of singularities outside black holes.
- Speaker: Professor Gary Horowitz - University of California, Santa Barbara
- Wednesday 14 May 2025, 16:00-17:00
- Venue: MR3.
- Series: Theoretical Physics Colloquium; organiser: Amanda Stagg.
Tue 15 Apr 11:00: Growing pains: the dining habits of stars, planets and black holes
To make planets, stars and supermassive black holes, one must rapidly accrete material onto central objects. But the tiniest tangential motion combined with angular momentum conservation sends material into orbit, rather than accreting. Since work at the IoA in the 1970s we have understood that Nature solves the angular momentum problem by forming accretion discs, but the angular momentum transport mechanism remains unclear. The past 10 years have given us spectacular resolved observations of discs around both young and old stars, bringing fresh clues. In this talk I’ll explain how pairing 3D simulations with observations helps us solve the problem of accretion, revealing how stars and planets form, black holes grow and how accretion powers tidal disruption events.
- Speaker: Daniel Price, Monash University
- Tuesday 15 April 2025, 11:00-12:00
- Venue: The Hoyle Lecture Theatre + Zoom .
- Series: Institute of Astronomy Seminars; organiser: Cristiano Longarini.
HR Administrator
Are you looking for an exciting opportunity in which to develop your Human Resources career in a world-leading academic department and University?
The Department:
The Cavendish Laboratory is the place of pioneering physics, that's been at the forefront of scientific discovery for 150 years, and will continue to be, because we never sit still. The Cavendish Laboratory has made several important discoveries, including: the discovery of the electron (1897), the neutron (1932), the structure of DNA (1953); thirty Cavendish researchers have won Nobel Prizes. We're trailblazers who continue to extend the frontiers of physics.
We have recently moved into our new state-of-the-art, multi-million pound Ray Dolby Centre which is the centrepiece of the new Cavendish Laboratory. This is an exciting and challenging time for the Department, and we would like to find a highly motivated individual with a positive attitude towards change and development to join us.
The Role:
We are seeking an enthusiastic and motivated HR Administrator to join a newly restructured, and vibrant HR team. The successful applicant will join a busy team of HR Administrators and Senior HR Coordinators who provide full support (both in person and via email) for all HR functions in the Department.
You will work closely with the Senior HR Coordinators and HR Manager to provide a professional and efficient HR service including all aspects of HR administration. Reporting directly to one of our Senior HR Coordinators, the role will provide clear and accurate advice on procedure, co-ordinating the recruitment and visitor processes and the onboarding of new starters (including dealing with all immigration and pre-employment paperwork). The position is busy and varied and has plenty of scope for training and development.
During the six month probation period, the roleholder will be required to work in the office full-time (Monday to Friday). After successful completion of their probation, we will agree up to 2 days per week working from home. This arrangement will depend on the operational needs of the team.
About You:
The ideal candidate will have HR administration experience but we will consider candidates who have excellent administrative and organisational skills; the ability to produce work to a high level of accuracy is essential.
The successful candidate will possess excellent interpersonal and administrative skills, and you will have the ability to work well within a busy team, fostering good working relationships with a wide variety of people from all over the world. You should be proficient in all standard Microsoft Office packages, highly organised, self-motivated, and able to prioritise your workload within a demanding environment. Tact and discretion are essential when handling confidential personal information. Previous HR experience whilst desirable is not essential.
We reserve the right to close this vacancy early if we receive sufficient applications for the role. Therefore, if you are interested, please submit your application as early as possible.
Previous applicants need not apply and no agencies please.
Once an offer of employment has been accepted, the successful candidate will be required to undergo a health assessment.
Click the 'Apply' button below to register an account with our recruitment system (if you have not already) and apply online.
Informal enquiries are welcome and should be sent to hr@phy.cam.ac.uk
Please quote reference KA43685 on your application and in any correspondence about this vacancy.
The University actively supports equality, diversity and inclusion and encourages applications from all sections of society.
The University has a responsibility to ensure that all employees are eligible to live and work in the UK.
Fri 09 May 11:30: How do the most luminous black holes accrete and expel gas?
The gravitational pull of a black hole attracts gas and forms an accretion disk where the interplay between hydromagnetic processes and the warping of space-time releases gravitational energy in the form of radiation, relativistic jets, and winds. Most gas falls into supermassive black holes when the accretion rate approaches the Eddington limit (L=Ledd), at which point radiation pressure overcomes gravity. To date, our knowledge of such `luminous’ black hole accretion disks mostly relies on semi-analytical models, supplemented by a limited set of numerical simulations. In my talk I will discuss new insights gained from state-of-the-art radiative general relativistic magnetohydrodynamics (GRMHD) simulations of accretion near the Eddington limit such as the formation of a hot corona, disk truncation, and other physical processes driving the spectral evolution of luminous black holes. I will finish my talk by discussing the challenges and opportunities the next-generation of GRMHD simulations will bring in developing a comprehensive understanding of black hole accretion across the luminosity spectrum.
- Speaker: Matthew Liska (Georgia Tech)
- Friday 09 May 2025, 11:30-12:30
- Venue: Hoyle Lecture Theatre .
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Tue 27 May 11:15: JAX-powered Bayesian anomaly detection for supernovae analysis
Abstract TBC
- Speaker: Samuel Leeney (University of Cambridge)
- Tuesday 27 May 2025, 11:15-12:00
- Venue: Martin Ryle Seminar Room, Kavli Institute.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Tue 15 Apr 11:00: Growing pains: the dining habits of stars, planets and black holes
To make planets, stars and supermassive black holes, one must rapidly accrete material onto central objects. But the tiniest tangential motion combined with angular momentum conservation sends material into orbit, rather than accreting. Since work at the IoA in the 1970s we have understood that Nature solves the angular momentum problem by forming accretion discs, but the angular momentum transport mechanism remains unclear. The past 10 years have given us spectacular resolved observations of discs around both young and old stars, bringing fresh clues. In this talk I’ll explain how pairing 3D simulations with observations helps us solve the problem of accretion, revealing how stars and planets form, black holes grow and how accretion powers tidal disruption events.
- Speaker: Daniel Price, Monash University
- Tuesday 15 April 2025, 11:00-12:00
- Venue: The Hoyle Lecture Theatre + Zoom .
- Series: Institute of Astronomy Seminars; organiser: Cristiano Longarini.
Fri 13 Jun 13:00: TBC
Abstract not available
- Speaker: Panos Giannadakis, Queen Mary University of London
- Friday 13 June 2025, 13:00-14:00
- Venue: Potter room/Zoom.
- Series: DAMTP Friday GR Seminar; organiser: Xi Tong.
Fri 06 Jun 13:00: TBC
Abstract not available
- Speaker: Marica Minucci, Bohr Inst., Copenhagen
- Friday 06 June 2025, 13:00-14:00
- Venue: Potter room/Zoom.
- Series: DAMTP Friday GR Seminar; organiser: Xi Tong.
Fri 02 May 13:00: TBC
Abstract not available
- Speaker: David Hilditch, Lisbon
- Friday 02 May 2025, 13:00-14:00
- Venue: Potter room/Zoom.
- Series: DAMTP Friday GR Seminar; organiser: Xi Tong.
Fri 25 Apr 13:00: TBC
Abstract not available
- Speaker: Ali Akil, Hong Kong University
- Friday 25 April 2025, 13:00-14:00
- Venue: Potter room/Zoom.
- Series: DAMTP Friday GR Seminar; organiser: Xi Tong.
Tue 20 May 11:15: A 21-cm Cosmologist’s Journey: From Cambridge to North America and Back Again
Abstract TBC
- Speaker: Dr. Peter Sims (University of Cambridge)
- Tuesday 20 May 2025, 11:15-12:00
- Venue: Martin Ryle Seminar Room, Kavli Institute.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Tue 27 May 11:15: Jax-powered Bayesian anomaly detection for supernovae analysis
Abstract TBC
- Speaker: Samuel Leeney (University of Cambridge)
- Tuesday 27 May 2025, 11:15-12:00
- Venue: Martin Ryle Seminar Room, Kavli Institute.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Tue 20 May 11:15: TBC
TBC
- Speaker: Dr. Peter Sims (University of Cambridge)
- Tuesday 20 May 2025, 11:15-12:00
- Venue: Martin Ryle Seminar Room, Kavli Institute.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Tue 27 May 11:15: Jax-powered Bayesian anomaly detection for supernovae analysis
TBC
- Speaker: Samuel Leeney (University of Cambridge)
- Tuesday 27 May 2025, 11:15-12:00
- Venue: Martin Ryle Seminar Room, Kavli Institute.
- Series: Hills Coffee Talks; organiser: Charles Walker.
Fri 11 Apr 11:30: Unveiling AGN Outflows: A High Resolution Morphological Study with LOFAR-VLBI
How AGN (Active Galactic Nuclei) feedback operates is one of the unsolved mysteries plaguing modern day astronomy. AGN outflows could explain how this feedback operates and, to investigate this, I use the [O III ] emission line as a tracer of ionised outflows. In this talk, I will present work investigating the link between low-frequency radio emission, using the LOFAR Two-meter Sky Survey Deep Fields at 144 MHz, and [O III ] kinematics, measured from SDSS spectroscopy, for a sample of optically selected AGN . We discover that radio detected AGN are more likely to host an [O III ] outflow compared to radio non-detected AGN . We observe a stronger broad, blue-shifted component in the radio-detected AGN , implying a profound link between low-frequency radio emission and [OIII] outflows. To further link AGN outflows to low-frequency radio emission, we harness the power of widefield VLBI (Very Long Baseline Interferometry) processing and imaging by incorporating the international stations of LOFAR into the data reduction process, to obtain sub-arcsecond radio images. To conclude this talk, I will present the first 0.3” resolution image at 144 MHz of the Boötes Deep Field and early results linking high resolution radio morphologies at 144 MHz to the presence of [O III ] outflows.
- Speaker: Emmy Escott (Durham)
- Friday 11 April 2025, 11:30-12:30
- Venue: Ryle Seminar Room, KICC + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Thu 08 May 14:00: How common are misaligned accretion disks around black holes?
Accretion disks around black holes emit across the electromagnetic spectrum, providing a window into strong-field gravity and extreme plasma environments. By analyzing their light curves and spectra, astrophysicists aim to probe fundamental questions about relativistic dynamics and high-energy astrophysics. Traditionally, models of black hole accretion have assumed that the disk’s angular momentum is aligned with the black hole’s spin axis. However, both observations and theoretical considerations increasingly suggest that misalignment—or tilt—is common. In this talk, I will present new insights from cutting-edge radiative general relativistic magnetohydrodynamic (GRMHD) simulations of tilted accretion disks. These simulations reveal that radiative cooling can induce a dramatic nonlinear response: disk warping leads to tearing, breaking the flow into discrete, misaligned sub-disks. The resulting dynamics naturally drive disk precession, which may underlie the quasi-periodic oscillations frequently observed in X-ray binaries and active galactic nuclei. In the second part of the talk, I will question the prevailing view that accretion is primarily driven by magnetorotational instability (MRI)-induced turbulence. I will show that in tilted, warped disks, accretion can instead be mediated by large-scale hydrodynamic shocks—specifically, nozzle shocks—offering a possible explanation for rapid luminosity variability in certain active galactic nuclei.
- Speaker: Matthew Liska (Georgia Tech)
- Thursday 08 May 2025, 14:00-15:00
- Venue: MR14 DAMTP and online.
- Series: DAMTP Astrophysics Seminars; organiser: Loren E. Held.