Revealing dark matter with small-scales dynamics
Lead Research Organisation:
Durham University
Department Name: Physics
Abstract
Since you started reading this, many millions of dark matter particles have gone through your body, at speeds of a few hundred miles per second. These particles are approximately four times more abundant than ordinary baryonic matter, yet their nature is still a puzzling mystery: my research is aimed to understand it.
The internal dynamics of galaxies and galaxy clusters, as well as the large-scale structure of the universe point to the existence of a pervasive form of matter, which interacts through gravity, but is invisible to electromagnetic radiation. Several different models have been proposed during the past decades, but we still do not know what such a 'dark matter' actually consists of, or how it relates to the Standard Model of particle physics. We know that galaxies are embedded in massive dark matter haloes, and that dark matter has a fundamental role in all of the processes that govern the formation and evolution of the galaxies themselves. For instance, the particles that are going through you right now are part of our own galaxy, the Milky Way.
The properties of dark matter particles can be constrained by studying the structure and dynamics of galaxies. After a long series of incremental advances, the coming decade will allow a number of breakthroughs in this field of research. Launched in December 2013, the Gaia satellite is currently measuring positions and velocities of billions of stars in the Milky Way, composing a full kinematic map of our galaxy of unprecedented size, extent and data quality. This map provides the instruments to revolutionise our understanding of how galaxies assemble through cosmic time and to finally test the predictions of different dark matter models. My research programme focuses on achieving both of these goals by exploiting Gaia data as well as data from a number of other upcoming dedicated major surveys.
The dark matter halo of the Milky Way has assembled hierarchically by accreting and engulfing several tens of smaller satellite galaxies. The Gaia satellite will provide a full record of this process, mapping the streaming debris of each of these disrupted dwarf galaxies. Gaia data contains a wealth of kinematic substructures and phase-space overdensities, each composed of stars originating from a common progenitor, still moving on similar orbits to the present day. With this data we will be able to reconstruct how the Galaxy formed and evolved, an invaluable `Rosetta Stone' to decode how millions of other galaxies assembled, driven by dark matter's gravity.
One of the crucial differences between competitive dark matter models is in the amount and properties of small-scale substructure in galaxy haloes. Gravitationally bound clumps of dark matter (subhalos) are abundant in the currently prevailing cold dark matter model, but much rarer or absent in a number of alternative models. Confirming or disproving the existence of subhaloes and measuring their abundance as a function of mass, pinpoints the dark matter power spectrum, and therefore the nature of the dark matter particle. Subhaloes are invisible, but can perturb the motion of the stars they happen to fly by to, through their gravity. The thin stellar streams formed by disrupting Globular Clusters are the best available 'dynamical dark matter detectors'. For the first time, the kinematic map provided by Gaia will have the precision necessary to detect these perturbations.
Dark matter has been a mystery for many decades, it is very exciting that so much progress is now possible within ten years.
The internal dynamics of galaxies and galaxy clusters, as well as the large-scale structure of the universe point to the existence of a pervasive form of matter, which interacts through gravity, but is invisible to electromagnetic radiation. Several different models have been proposed during the past decades, but we still do not know what such a 'dark matter' actually consists of, or how it relates to the Standard Model of particle physics. We know that galaxies are embedded in massive dark matter haloes, and that dark matter has a fundamental role in all of the processes that govern the formation and evolution of the galaxies themselves. For instance, the particles that are going through you right now are part of our own galaxy, the Milky Way.
The properties of dark matter particles can be constrained by studying the structure and dynamics of galaxies. After a long series of incremental advances, the coming decade will allow a number of breakthroughs in this field of research. Launched in December 2013, the Gaia satellite is currently measuring positions and velocities of billions of stars in the Milky Way, composing a full kinematic map of our galaxy of unprecedented size, extent and data quality. This map provides the instruments to revolutionise our understanding of how galaxies assemble through cosmic time and to finally test the predictions of different dark matter models. My research programme focuses on achieving both of these goals by exploiting Gaia data as well as data from a number of other upcoming dedicated major surveys.
The dark matter halo of the Milky Way has assembled hierarchically by accreting and engulfing several tens of smaller satellite galaxies. The Gaia satellite will provide a full record of this process, mapping the streaming debris of each of these disrupted dwarf galaxies. Gaia data contains a wealth of kinematic substructures and phase-space overdensities, each composed of stars originating from a common progenitor, still moving on similar orbits to the present day. With this data we will be able to reconstruct how the Galaxy formed and evolved, an invaluable `Rosetta Stone' to decode how millions of other galaxies assembled, driven by dark matter's gravity.
One of the crucial differences between competitive dark matter models is in the amount and properties of small-scale substructure in galaxy haloes. Gravitationally bound clumps of dark matter (subhalos) are abundant in the currently prevailing cold dark matter model, but much rarer or absent in a number of alternative models. Confirming or disproving the existence of subhaloes and measuring their abundance as a function of mass, pinpoints the dark matter power spectrum, and therefore the nature of the dark matter particle. Subhaloes are invisible, but can perturb the motion of the stars they happen to fly by to, through their gravity. The thin stellar streams formed by disrupting Globular Clusters are the best available 'dynamical dark matter detectors'. For the first time, the kinematic map provided by Gaia will have the precision necessary to detect these perturbations.
Dark matter has been a mystery for many decades, it is very exciting that so much progress is now possible within ten years.
Organisations
People |
ORCID iD |
Nicola Cristiano Amorisco (Principal Investigator / Fellow) |
Publications
Saifollahi T
(2022)
Implications for galaxy formation models from observations of globular clusters around ultradiffuse galaxies
in Monthly Notices of the Royal Astronomical Society
He Q
(2022)
Galaxy-galaxy strong lens perturbations: line-of-sight haloes versus lens subhaloes
in Monthly Notices of the Royal Astronomical Society
Deason A
(2022)
Dwarf stellar haloes: a powerful probe of small-scale galaxy formation and the nature of dark matter
in Monthly Notices of the Royal Astronomical Society
Cao X
(2022)
Systematic Errors Induced by the Elliptical Power-law model in Galaxy-Galaxy Strong Lens Modeling
in Research in Astronomy and Astrophysics
Amorisco N
(2022)
Halo concentration strengthens dark matter constraints in galaxy-galaxy strong lensing analyses
in Monthly Notices of the Royal Astronomical Society
Amorisco N
(2021)
Cold dark matter subhaloes at arbitrarily low masses
Description | Talk at Durham University, title: Constraining the dark matter halo mass function with Deep Learning |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Postgraduate students |
Results and Impact | This (online) presentation was aimed at presenting a range of new Machine Learning techniques to the community at Durham University involved in Dark Matter studies. Between 15 and 25 attendees including postgraduate students, PDRAs and staff. |
Year(s) Of Engagement Activity | 2020 |
Description | Talk at Durham University, title: Experiments in Machine-Rewinding Hierarchical Assembly |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Postgraduate students |
Results and Impact | This (online) presentation was aimed at introducing my research project to the Astronomy community at Durham University. I described techniques and initial results. Between 40 and 50 attendees including postgraduate students, PDRAs and staff. |
Year(s) Of Engagement Activity | 2020 |