Neon sign identified by JWST gives clue to planet formation
The winds that help to form planets in the gaseous discs of early solar systems have been imaged for the first time by the James Webb Space Telescope (JWST) using the noble gases neon and argon. Planetary systems like our Solar System seem to contain more rocky objects than gas-rich ones. Around our sun, these include the...
Europa may have less oxygen to fuel life in its seas than we thought
Fri 08 Mar 11:30: Obscured AGN across cosmic time
The bulk of the growth of supermassive black holes over cosmic time takes place behind heavy obscuration. I will present observational evidence that much, or even most, of these AGN are very heavily obscured (Compton-thick) and thus hidden from many previous multiwavelength surveys. I will discuss the implications for cosmic black hole growth and the populations of AGN now detected in the early Universe with JWST .
- Speaker: Ryan Hickox (Dartmouth)
- Friday 08 March 2024, 11:30-12:30
- Venue: Ryle seminar room + online.
- Series: Galaxies Discussion Group; organiser: Sandro Tacchella.
Fri 08 Mar 13:00: The Fate of Matter Fields in Metric-Affine Gravity
General relativity (GR) exists in different formulations. They are equivalent in pure gravity but generically lead to distinct predictions once matter is included. After a brief overview of various versions of GR, I will focus on metric-affine gravity, which avoids any assumption about the vanishing of curvature, torsion, or nonmetricity. With a view toward the Standard Model, we can construct a generic model of (complex) scalar, fermionic, and gauge fields coupled to GR and derive an equivalent metric theory, which features numerous new interaction terms. There are multiple phenomenological consequences, which I will detail: an improved setting for Higgs inflation, a new (purely gravitational) production channel for fermionic dark matter, and an outlook on axion inflation.
- Speaker: Claire Rigouzzo (KCL)
- Friday 08 March 2024, 13:00-14:00
- Venue: Potter room/Zoom.
- Series: DAMTP Friday GR Seminar; organiser: Daniela Cors.
Tue 12 Mar 13:00: Relative contribution from comets and carbonaceous asteroids to the Earth's volatile budget
Recent models of solar system formation suggest that a dynamical instability among the giant planets happened within the first 100 Myr after disk dispersal, perhaps before the Moon-forming impact. As a direct consequence, a bombardment of volatile-rich impactors may have taken place on Earth before internal and atmospheric reservoirs were decoupled. However, such a timing has been interpreted to potentially be at odds with the disparate inventories of Xe isotopes in Earth’s mantle compared to its atmosphere. In this seminar, I will talk about the dynamical effects of an Early Instability on the delivery of carbonaceous asteroids and comets to Earth, and address the implications for the Earth’s volatile budget.
- Speaker: Sarah Joiret (U Bordeaux)
- Tuesday 12 March 2024, 13:00-14:00
- Venue: Ryle seminar room + ONLINE - Details to be sent by email.
- Series: Exoplanet Seminars; organiser: Dr Emily Sandford.
GN-z11: The environment of an AGN at $z=$10.603
A rare astrolabe discovery reveals Islamic–Jewish scientific exchange
The identification of an eleventh-century Islamic astrolabe bearing both Arabic and Hebrew inscriptions makes it one of the oldest examples ever discovered and one of only a handful known in the world. The astronomical instrument was adapted, translated and corrected for centuries by Muslim, Jewish and Christian users in Spain, North Africa and Italy.
Wed 06 Mar 13:15: The Nature of Dark Matter with Lyman-Alpha Forest
The existence of dark matter, which constitutes 85% of the matter density and 26% of the total energy density, is clearly demonstrated by cosmological observations of the Universe. And yet, very little is known about the nature of dark matter. The observations support the ‘cold dark matter’ (CDM) paradigm, in which the dark matter is a heavy particle, with little to no interactions through fundamental forces other than gravity. The cosmological and astrophysical observations of dark matter’s gravitational interaction currently provide the only robust evidence of dark matter. These observations typically rely on characterising the distribution of matter in the Universe. A dark matter particle that is lighter than the standard CDM paradigm predicts imprints a suppression of structure in the matter distribution. The exact scale where this happens is most often linked to the mass of the dark matter particle. I will present new results on the thermal relic warm dark matter constraints using the high-redshift cosmic web as traced by the Lyman-alpha forest.
- Speaker: Vid Iršič
- Wednesday 06 March 2024, 13:15-13:40
- Venue: The Hoyle Lecture Theatre + Zoom .
- Series: Institute of Astronomy Seminars; organiser: .
Wed 06 Mar 13:15: The Nature of Dark Matter with Lyman-Alpha Forest
The existence of dark matter, which constitutes 85% of the matter density and 26% of the total energy density, is clearly demonstrated by cosmological observations of the Universe. And yet, very little is known about the nature of dark matter. The observations support the ‘cold dark matter’ (CDM) paradigm, in which the dark matter is a heavy particle, with little to no interactions through fundamental forces other than gravity. The cosmological and astrophysical observations of dark matter’s gravitational interaction currently provide the only robust evidence of dark matter. These observations typically rely on characterising the distribution of matter in the Universe. A dark matter particle that is lighter than the standard CDM paradigm predicts imprints a suppression of structure in the matter distribution. The exact scale where this happens is most often linked to the mass of the dark matter particle. I will present new results on the thermal relic warm dark matter constraints using the high-redshift cosmic web as traced by the Lyman-alpha forest.
- Speaker: Vid Iršič
- Wednesday 06 March 2024, 13:15-13:40
- Venue: The Hoyle Lecture Theatre + Zoom .
- Series: Institute of Astronomy Seminars; organiser: .
Why space dust is key to everything from star birth to life on Earth
Brightest and hungriest black hole ever detected
Astronomers crack 37-year cosmic 'murder mystery'
Frozen antimatter may reveal origins of Universe
Particle initialization effects on Lyman-$\alpha$ forest statistics in cosmological SPH simulations
A heuristic account of the radiation by the superluminally moving current sheet in the magnetosphere of a neutron star
Physical Pathways for JWST-Observed Supermassive Black Holes in the Early Universe
The DESI Early Data Release White Dwarf Catalogue
Using Rest-Frame Optical and NIR Data from the RAISIN Survey to Explore the Redshift Evolution of Dust Laws in SN Ia Host Galaxies
Two giant US telescopes threatened by funding cap
Nature, Published online: 29 February 2024; doi:10.1038/d41586-024-00623-6
Thirty Meter Telescope and Giant Magellan Telescope might need to compete for survival in face of federal spending limit.This dying star bears a jagged metal scar
Nature, Published online: 29 February 2024; doi:10.1038/d41586-024-00564-0
The surface of a white dwarf is marked with metallic patches — souvenirs of its encounter with an asteroid or planet.