Project acronym AIDA
Project An Illumination of the Dark Ages: modeling reionization and interpreting observations
Researcher (PI) Andrei Albert Mesinger
Host Institution (HI) SCUOLA NORMALE SUPERIORE
Call Details Starting Grant (StG), PE9, ERC-2014-STG
Summary "Understanding the dawn of the first galaxies and how their light permeated the early Universe is at the very frontier of modern astrophysical cosmology. Generous resources, including ambitions observational programs, are being devoted to studying these epochs of Cosmic Dawn (CD) and Reionization (EoR). In order to interpret these observations, we propose to build on our widely-used, semi-numeric simulation tool, 21cmFAST, and apply it to observations. Using sub-grid, semi-analytic models, we will incorporate additional physical processes governing the evolution of sources and sinks of ionizing photons. The resulting state-of-the-art simulations will be well poised to interpret topical observations of quasar spectra and the cosmic 21cm signal. They would be both physically-motivated and fast, allowing us to rapidly explore astrophysical parameter space. We will statistically quantify the resulting degeneracies and constraints, providing a robust answer to the question, ""What can we learn from EoR/CD observations?"" As an end goal, these investigations will help us understand when the first generations of galaxies formed, how they drove the EoR, and what are the associated large-scale observational signatures."
Summary
"Understanding the dawn of the first galaxies and how their light permeated the early Universe is at the very frontier of modern astrophysical cosmology. Generous resources, including ambitions observational programs, are being devoted to studying these epochs of Cosmic Dawn (CD) and Reionization (EoR). In order to interpret these observations, we propose to build on our widely-used, semi-numeric simulation tool, 21cmFAST, and apply it to observations. Using sub-grid, semi-analytic models, we will incorporate additional physical processes governing the evolution of sources and sinks of ionizing photons. The resulting state-of-the-art simulations will be well poised to interpret topical observations of quasar spectra and the cosmic 21cm signal. They would be both physically-motivated and fast, allowing us to rapidly explore astrophysical parameter space. We will statistically quantify the resulting degeneracies and constraints, providing a robust answer to the question, ""What can we learn from EoR/CD observations?"" As an end goal, these investigations will help us understand when the first generations of galaxies formed, how they drove the EoR, and what are the associated large-scale observational signatures."
Max ERC Funding
1 468 750 €
Duration
Start date: 2015-05-01, End date: 2021-01-31
Project acronym COEVOLUTION
Project Black holes and their host galaxies: coevolution across cosmic time
Researcher (PI) Debora Sijacki
Host Institution (HI) THE CHANCELLOR MASTERS AND SCHOLARS OF THE UNIVERSITY OF CAMBRIDGE
Call Details Starting Grant (StG), PE9, ERC-2014-STG
Summary Galaxy formation is one of the most fascinating yet challenging fields of astrophysics. The desire to understand
galaxy formation has led to the design of ever more sophisticated telescopes which show a bewildering variety
of galaxies in the Universe. However, the degree to which an interpretation of this wealth of data can succeed
depends critically on having accurate and realistic theoretical models of galaxy formation. While cosmological
simulations of galaxy formation provide the most powerful technique for calculating the non-linear evolution of
cosmic structures, the enormous dynamic range and poorly understood baryonic physics are main uncertainties
of present simulations. This impacts on their predictive power and is the major obstacle to our understanding of
observational data. The objective of this proposal is to drastically improve upon the current state-of-the-art by i)
including more realistic physical processes, such as those occurring at the sphere of influence of a galaxy’s central
black hole and ii) greatly extending spatial dynamical range with the aid of a novel technique I have developed.
With this technique I want to address one of the major unsolved issues of galaxy formation: “How do galaxies and
their central black holes coevolve?” Specifically, I want to focus on three crucial areas of galaxy formation: a) How
and where the very first black holes form, what are their observational signatures, and when is the coevolution with
host galaxies established? b) Is black hole heating solely responsible for the morphological transformation and
quenching of massive galaxies, or are other processes important as well? c) What is the impact of supermassive
black holes on galaxy clusters and can we calibrate baryonic physics in clusters to use them as high precision
cosmological probes? The requested funding is for 50% of the PI’s time and three postdoctoral researchers to
establish an independent research group at the KICC and IoA, Cambridge.
Summary
Galaxy formation is one of the most fascinating yet challenging fields of astrophysics. The desire to understand
galaxy formation has led to the design of ever more sophisticated telescopes which show a bewildering variety
of galaxies in the Universe. However, the degree to which an interpretation of this wealth of data can succeed
depends critically on having accurate and realistic theoretical models of galaxy formation. While cosmological
simulations of galaxy formation provide the most powerful technique for calculating the non-linear evolution of
cosmic structures, the enormous dynamic range and poorly understood baryonic physics are main uncertainties
of present simulations. This impacts on their predictive power and is the major obstacle to our understanding of
observational data. The objective of this proposal is to drastically improve upon the current state-of-the-art by i)
including more realistic physical processes, such as those occurring at the sphere of influence of a galaxy’s central
black hole and ii) greatly extending spatial dynamical range with the aid of a novel technique I have developed.
With this technique I want to address one of the major unsolved issues of galaxy formation: “How do galaxies and
their central black holes coevolve?” Specifically, I want to focus on three crucial areas of galaxy formation: a) How
and where the very first black holes form, what are their observational signatures, and when is the coevolution with
host galaxies established? b) Is black hole heating solely responsible for the morphological transformation and
quenching of massive galaxies, or are other processes important as well? c) What is the impact of supermassive
black holes on galaxy clusters and can we calibrate baryonic physics in clusters to use them as high precision
cosmological probes? The requested funding is for 50% of the PI’s time and three postdoctoral researchers to
establish an independent research group at the KICC and IoA, Cambridge.
Max ERC Funding
1 975 062 €
Duration
Start date: 2015-09-01, End date: 2020-08-31
Project acronym CSINEUTRONSTAR
Project The physics and forensics of neutron star explosions
Researcher (PI) Anna Louise Watts
Host Institution (HI) UNIVERSITEIT VAN AMSTERDAM
Call Details Starting Grant (StG), PE9, ERC-2014-STG
Summary Neutron stars offer a unique environment in which to develop and test theories of the strong force. Densities in neutron star cores can reach up to ten times the density of a normal atomic nucleus, and the stabilizing effect of gravitational confinement permits long-timescale weak interactions. This generates matter that is neutron-rich, and opens up the possibility of stable states of strange matter, something that can only exist in neutron stars. Strong force physics is encoded in the Equation of State (EOS), the pressure-density relation. This is linked to macroscopic observables such as mass M and radius R via the stellar structure equations. By measuring and inverting the M-R relation we can recover the EOS and diagnose the underlying dense matter physics.
This proposal focuses on a very promising technique for simultaneous measurement of M and R. It exploits hotspots (burst oscillations) that form on the neutron star surface when material accreted from a companion star undergoes a thermonuclear explosion (a Type I X-ray burst). As the star rotates, the hotspot gives rise to a pulsation. Relativistic effects then encode information about M and R into the pulse profile. However the mechanism that generates burst oscillations remains unknown, 18 years after their discovery. This is frustrating in terms of our understanding of thermonuclear bursts. It also leads to uncertainties in the precise form of the underlying surface emission pattern (a key factor in the pulse profile fitting process), which must be addressed to cement their reliability as diagnostics of M and R.
This proposal has two objectives. Firstly, to resolve the burst oscillation mechanism via an ambitious programme of theoretical and observational analysis. Secondly, to ensure that burst oscillations are a robust tool for measurement of M and R by determining the effect of the surface pattern uncertainty on pulse profile fitting, independent of efforts to constrain the mechanism.
Summary
Neutron stars offer a unique environment in which to develop and test theories of the strong force. Densities in neutron star cores can reach up to ten times the density of a normal atomic nucleus, and the stabilizing effect of gravitational confinement permits long-timescale weak interactions. This generates matter that is neutron-rich, and opens up the possibility of stable states of strange matter, something that can only exist in neutron stars. Strong force physics is encoded in the Equation of State (EOS), the pressure-density relation. This is linked to macroscopic observables such as mass M and radius R via the stellar structure equations. By measuring and inverting the M-R relation we can recover the EOS and diagnose the underlying dense matter physics.
This proposal focuses on a very promising technique for simultaneous measurement of M and R. It exploits hotspots (burst oscillations) that form on the neutron star surface when material accreted from a companion star undergoes a thermonuclear explosion (a Type I X-ray burst). As the star rotates, the hotspot gives rise to a pulsation. Relativistic effects then encode information about M and R into the pulse profile. However the mechanism that generates burst oscillations remains unknown, 18 years after their discovery. This is frustrating in terms of our understanding of thermonuclear bursts. It also leads to uncertainties in the precise form of the underlying surface emission pattern (a key factor in the pulse profile fitting process), which must be addressed to cement their reliability as diagnostics of M and R.
This proposal has two objectives. Firstly, to resolve the burst oscillation mechanism via an ambitious programme of theoretical and observational analysis. Secondly, to ensure that burst oscillations are a robust tool for measurement of M and R by determining the effect of the surface pattern uncertainty on pulse profile fitting, independent of efforts to constrain the mechanism.
Max ERC Funding
1 499 999 €
Duration
Start date: 2015-06-01, End date: 2020-05-31
Project acronym FirstDawn
Project Imaging the cosmic dawn and the first galaxies with 21cm and atomic line intensity mapping
Researcher (PI) Jonathan Robin Pritchard
Host Institution (HI) IMPERIAL COLLEGE OF SCIENCE TECHNOLOGY AND MEDICINE
Call Details Starting Grant (StG), PE9, ERC-2014-STG
Summary "Modern astrophysics has pushed the observational frontier to a time a billion years after the Big Bang. Lying beyond this frontier is the period when the first stars and galaxies formed, whose light heated and ionized the Universe in the process known as reionization. Understanding this ""epoch of reionization"" would fill in a key missing period in our picture of the history of the Universe. Existing observational techniques have scratched the surface, but new observational techniques are required to truly understand this early period of galaxy formation. My work will lay the theoretical foundations for three novel probes of this period - 21 cm tomography, the 21 cm global signal, and line intensity mapping - that would enable three dimensional maps of the epoch of reionization. If realized through challenging radio-frequency observations, these techniques would transform our understanding of the first galaxies.
Through this ERC starting grant, I will build the theoretical framework needed to predict and interpret observations of line emission from gas in and surrounding the first generation of galaxies. My team will aim to develop models of the interplay between radiation from the first galaxies and the heating, ionization, and illumination of hydrogen gas that lies in the space between galaxies. At the same time, we will build models of the formation and properties of the atomic and molecular gas that fills the space inside galaxies. By combining probes of this ""inner"" and ""outer"" space a complete nature of galaxy formation during the first billion years might be achieved. Analysis of sky averaged 21 cm observations will complement this with a broad overview of galaxies back to a few hundred million years after the big bang. This work will provide a clear theoretical road map to guide the design of next generation radio telescopes, such as the Square Kilometer Array, to achieve this ambitious goal."
Summary
"Modern astrophysics has pushed the observational frontier to a time a billion years after the Big Bang. Lying beyond this frontier is the period when the first stars and galaxies formed, whose light heated and ionized the Universe in the process known as reionization. Understanding this ""epoch of reionization"" would fill in a key missing period in our picture of the history of the Universe. Existing observational techniques have scratched the surface, but new observational techniques are required to truly understand this early period of galaxy formation. My work will lay the theoretical foundations for three novel probes of this period - 21 cm tomography, the 21 cm global signal, and line intensity mapping - that would enable three dimensional maps of the epoch of reionization. If realized through challenging radio-frequency observations, these techniques would transform our understanding of the first galaxies.
Through this ERC starting grant, I will build the theoretical framework needed to predict and interpret observations of line emission from gas in and surrounding the first generation of galaxies. My team will aim to develop models of the interplay between radiation from the first galaxies and the heating, ionization, and illumination of hydrogen gas that lies in the space between galaxies. At the same time, we will build models of the formation and properties of the atomic and molecular gas that fills the space inside galaxies. By combining probes of this ""inner"" and ""outer"" space a complete nature of galaxy formation during the first billion years might be achieved. Analysis of sky averaged 21 cm observations will complement this with a broad overview of galaxies back to a few hundred million years after the big bang. This work will provide a clear theoretical road map to guide the design of next generation radio telescopes, such as the Square Kilometer Array, to achieve this ambitious goal."
Max ERC Funding
1 495 220 €
Duration
Start date: 2015-04-01, End date: 2020-03-31
Project acronym GalNUC
Project Astrophysical Dynamics and Statistical Physics of Galactic Nuclei
Researcher (PI) Bence Kocsis
Host Institution (HI) EOTVOS LORAND TUDOMANYEGYETEM
Call Details Starting Grant (StG), PE9, ERC-2014-STG
Summary We address some of the major unsolved questions of galactic nuclei using methods of condensed matter physics. Galactic nuclei host a central supermassive black hole, a dense population of stars and compact objects, and in many cases a bright gaseous disk feeding the supermassive black hole. The observed stellar distribution exhibits both spherical and counterrotating disk-like structures. Existing theoretical models cannot convincingly explain the origin of the stellar disks. Is there also a “dark cusp” or “dark disk” of stellar mass black holes? Are there intermediate mass black holes in the Galactic center? We examine the statistical physics of galactic nuclei and their long term dynamical evolution. A star orbiting a supermassive black hole on an eccentric precessing orbit covers an axisymmetric annulus. The long-term gravitational interaction between such annuli is similar to the Coulomb interaction between axisymmetric molecules constituting a liquid crystal. We apply standard methods of condensed matter physics to examine these astrophysical systems. The observed disk and spherical structures represent isotropic-nematic phase transitions. We derive the phase space distribution and time-evolution of different stellar components including a population of black holes. Further, we investigate the interaction of a stellar cluster with a gaseous disk, if present. This leads to the formation of gaps, warps, and spiral waves in the disk, the redistribution of stellar objects, and possibly the formation of intermediate mass black holes. We explore the implications for electromagnetic and gravitational wave observatories. Dark disks of black holes could provide the most frequent source of gravitational waves for LIGO and VIRGO. These detectors will open a new window on the Universe; the proposed project will open a new field in gravitational wave astrophysics to interpret the sources. We also explore implications for electromagnetic observations.
Summary
We address some of the major unsolved questions of galactic nuclei using methods of condensed matter physics. Galactic nuclei host a central supermassive black hole, a dense population of stars and compact objects, and in many cases a bright gaseous disk feeding the supermassive black hole. The observed stellar distribution exhibits both spherical and counterrotating disk-like structures. Existing theoretical models cannot convincingly explain the origin of the stellar disks. Is there also a “dark cusp” or “dark disk” of stellar mass black holes? Are there intermediate mass black holes in the Galactic center? We examine the statistical physics of galactic nuclei and their long term dynamical evolution. A star orbiting a supermassive black hole on an eccentric precessing orbit covers an axisymmetric annulus. The long-term gravitational interaction between such annuli is similar to the Coulomb interaction between axisymmetric molecules constituting a liquid crystal. We apply standard methods of condensed matter physics to examine these astrophysical systems. The observed disk and spherical structures represent isotropic-nematic phase transitions. We derive the phase space distribution and time-evolution of different stellar components including a population of black holes. Further, we investigate the interaction of a stellar cluster with a gaseous disk, if present. This leads to the formation of gaps, warps, and spiral waves in the disk, the redistribution of stellar objects, and possibly the formation of intermediate mass black holes. We explore the implications for electromagnetic and gravitational wave observatories. Dark disks of black holes could provide the most frequent source of gravitational waves for LIGO and VIRGO. These detectors will open a new window on the Universe; the proposed project will open a new field in gravitational wave astrophysics to interpret the sources. We also explore implications for electromagnetic observations.
Max ERC Funding
1 511 436 €
Duration
Start date: 2015-08-01, End date: 2020-07-31
Project acronym ImagePlanetFormDiscs
Project Imaging the Dynamical Imprints of Planet Formation in Protoplanetary Discs
Researcher (PI) Stefan Kraus
Host Institution (HI) THE UNIVERSITY OF EXETER
Call Details Starting Grant (StG), PE9, ERC-2014-STG
Summary The gas and dust discs around young stars are thought to be the birthplace of planetary systems and are a key area to study if further progress is to be made on understanding the history of our solar system and our own origins. Once planets have formed in these discs, they dynamically sculpt their environment, for instance by opening tidally-cleared gaps or triggering spiral arms and disc warps. The late stages of this process are likely observed in the “transitional” discs, where regions spanning tens of astronomical units (AU) have been cleared. The aim of this project is to image the planet formation signatures both during the transitional disc and the earlier T Tauri or Herbig Ae/Be stars phase, where the protoplanetary bodies are just starting to carve gaps in the optically thick disc. For this purpose, we will employ the latest generation of near-infrared, mid-infrared, and sub-millimeter interferometric instruments that will allow us to trace a wide range of stellocentric radii, disc scale heights, and dust opacities. We will make use of recent revolutionary advancements in infrared detector technology and equip the CHARA/MIRC 6-telescope beam combiner with a low-read noise camera that will significantly increase the sensitivity of this instrument and enable us to image protoplanetary discs with 2.5 times higher resolution and much higher efficiency than ever before. These quick-look imaging capabilities will enable us to trace time-variable structures in the inner few AU and to investigate their relation to the commonly observed photometric and spectroscopic variability. Our interferometric observations in spectral lines aim to detect the accretion signatures of the young protoplanets themselves. Employing sophisticated radiation hydrodynamics simulations we will achieve an unprecedented global view on protoplanetary disc structure and obtain fundamentally new constraints on theoretical models of planet formation, planet-disc interaction, and disc evolution.
Summary
The gas and dust discs around young stars are thought to be the birthplace of planetary systems and are a key area to study if further progress is to be made on understanding the history of our solar system and our own origins. Once planets have formed in these discs, they dynamically sculpt their environment, for instance by opening tidally-cleared gaps or triggering spiral arms and disc warps. The late stages of this process are likely observed in the “transitional” discs, where regions spanning tens of astronomical units (AU) have been cleared. The aim of this project is to image the planet formation signatures both during the transitional disc and the earlier T Tauri or Herbig Ae/Be stars phase, where the protoplanetary bodies are just starting to carve gaps in the optically thick disc. For this purpose, we will employ the latest generation of near-infrared, mid-infrared, and sub-millimeter interferometric instruments that will allow us to trace a wide range of stellocentric radii, disc scale heights, and dust opacities. We will make use of recent revolutionary advancements in infrared detector technology and equip the CHARA/MIRC 6-telescope beam combiner with a low-read noise camera that will significantly increase the sensitivity of this instrument and enable us to image protoplanetary discs with 2.5 times higher resolution and much higher efficiency than ever before. These quick-look imaging capabilities will enable us to trace time-variable structures in the inner few AU and to investigate their relation to the commonly observed photometric and spectroscopic variability. Our interferometric observations in spectral lines aim to detect the accretion signatures of the young protoplanets themselves. Employing sophisticated radiation hydrodynamics simulations we will achieve an unprecedented global view on protoplanetary disc structure and obtain fundamentally new constraints on theoretical models of planet formation, planet-disc interaction, and disc evolution.
Max ERC Funding
1 648 265 €
Duration
Start date: 2015-07-01, End date: 2020-06-30
Project acronym LITHIUM
Project From planetary birth with aperture masking interferometry to nulling with Lithium Niobate technology
Researcher (PI) Sylvestre Mathieu André Lacour
Host Institution (HI) CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
Call Details Starting Grant (StG), PE9, ERC-2014-STG
Summary Observing the process of planetary accretion is crucial to inform models of planet formation. Most of the key action is expected to happen in the gaps of protostellar disks – a spatial realm over which aperture masking interferometry has demonstrated a unique ability to deliver incisive imaging. Masking offers twin advantages of higher dynamic range at the diffraction limit (lambda/D) than differential imaging, while at the same time giving nearly complete Fourier coverage compared to long baseline interferometry. The founding objective of this proposal is to create expertise and technology to understand the astrophysical phenomena so far only glimpsed in faint detections in stellar gaps such as those published in T Cha (Huelamo et al. 2011), HD142527 (Biller et al. 2012) and FL Cha (Cieza et al. 2013). But the central goal of this project is to further advance the experimental technique. Reaching even higher dynamic range for fainter detections is essential for probing planetary birth. The way to improve the dynamic range is clear: increase the accuracy of the primary closure phase observable. To do so, we will follow two paths. The first will use laboratory experimentations to analyse and understand the sources of bias to the closure phase. The resulting end-product will be better software offered to the community, and better techniques for a next generation of aperture masking devices. The second path is to amplify the closure phase signal by combining nulling with closure phase (Lacour et al. 2014). This second path is the most challenging, but will be an important breakthrough to the field. Nulling is to aperture masking what coronagraphy is to classical imaging. Without a first level of nulling, the aperture masking technique will always be limited by the photon noise due to the stellar light. We propose to build on our experience of Lithium Niobate integrated optics devices to bring aperture masking to a new level of performance in high dynamic range imaging.
Summary
Observing the process of planetary accretion is crucial to inform models of planet formation. Most of the key action is expected to happen in the gaps of protostellar disks – a spatial realm over which aperture masking interferometry has demonstrated a unique ability to deliver incisive imaging. Masking offers twin advantages of higher dynamic range at the diffraction limit (lambda/D) than differential imaging, while at the same time giving nearly complete Fourier coverage compared to long baseline interferometry. The founding objective of this proposal is to create expertise and technology to understand the astrophysical phenomena so far only glimpsed in faint detections in stellar gaps such as those published in T Cha (Huelamo et al. 2011), HD142527 (Biller et al. 2012) and FL Cha (Cieza et al. 2013). But the central goal of this project is to further advance the experimental technique. Reaching even higher dynamic range for fainter detections is essential for probing planetary birth. The way to improve the dynamic range is clear: increase the accuracy of the primary closure phase observable. To do so, we will follow two paths. The first will use laboratory experimentations to analyse and understand the sources of bias to the closure phase. The resulting end-product will be better software offered to the community, and better techniques for a next generation of aperture masking devices. The second path is to amplify the closure phase signal by combining nulling with closure phase (Lacour et al. 2014). This second path is the most challenging, but will be an important breakthrough to the field. Nulling is to aperture masking what coronagraphy is to classical imaging. Without a first level of nulling, the aperture masking technique will always be limited by the photon noise due to the stellar light. We propose to build on our experience of Lithium Niobate integrated optics devices to bring aperture masking to a new level of performance in high dynamic range imaging.
Max ERC Funding
1 851 881 €
Duration
Start date: 2015-03-01, End date: 2020-02-29
Project acronym LOFAR
Project Searching for The Origin of Cosmic Rays and Neutrinos with LOFAR
Researcher (PI) Stijn Buitink
Host Institution (HI) VRIJE UNIVERSITEIT BRUSSEL
Call Details Starting Grant (StG), PE9, ERC-2014-STG
Summary The origin of cosmic rays remains one of the largest mysteries in astrophysics. Innovative and accurate radio measurements of cosmic rays and neutrinos with LOFAR promise to provide new answers.
It is generally believed that ultra-high-energy cosmic rays are produced in extragalactic sources like gamma- ray bursts or active galactic nuclei, while the lower energy cosmic rays come from our own Galaxy. At what energy this transition takes place is still unknown. Here we focus on disentangling Galactic and extragalactic components by studying the mass composition between 10^17 and 10^18 eV, a regime that is also crucial for understanding the origin of the extraterrestrial neutrinos detected by IceCube.
We do this with LOFAR, the first radio telescope that can detect individual cosmic rays with hundreds of antennas. This incredible level of detail allowed us to finally understand the complicated radiation mechanism and to perform the first-ever accurate mass analysis based on radio measurements. Our first data reveal a strong proton component below 10^18 eV, suggesting an early transition to an extragalactic component. With upgrades to our detector and techniques we will be able to improve our sample size by an order of magnitude, resolve more mass components, and identify the origin of high-energy cosmic rays and neutrinos.
The technique may be scaled up to higher energies, measured at the Pierre Auger Observatory, where mass information is needed to correlate cosmic rays with their astrophysical sources and to confirm the nature of the cutoff at ~10^19.6 eV.
We can even search for particles beyond the GZK limit. With the Westerbork telescope we have already set the best limit on cosmic rays and neutrinos above 10^23 eV. With LOFAR we will achieve a much better sensitivity at lower energies, also probing for new physics, like the decays of cosmic strings predicted by supersymmetric theories.
Summary
The origin of cosmic rays remains one of the largest mysteries in astrophysics. Innovative and accurate radio measurements of cosmic rays and neutrinos with LOFAR promise to provide new answers.
It is generally believed that ultra-high-energy cosmic rays are produced in extragalactic sources like gamma- ray bursts or active galactic nuclei, while the lower energy cosmic rays come from our own Galaxy. At what energy this transition takes place is still unknown. Here we focus on disentangling Galactic and extragalactic components by studying the mass composition between 10^17 and 10^18 eV, a regime that is also crucial for understanding the origin of the extraterrestrial neutrinos detected by IceCube.
We do this with LOFAR, the first radio telescope that can detect individual cosmic rays with hundreds of antennas. This incredible level of detail allowed us to finally understand the complicated radiation mechanism and to perform the first-ever accurate mass analysis based on radio measurements. Our first data reveal a strong proton component below 10^18 eV, suggesting an early transition to an extragalactic component. With upgrades to our detector and techniques we will be able to improve our sample size by an order of magnitude, resolve more mass components, and identify the origin of high-energy cosmic rays and neutrinos.
The technique may be scaled up to higher energies, measured at the Pierre Auger Observatory, where mass information is needed to correlate cosmic rays with their astrophysical sources and to confirm the nature of the cutoff at ~10^19.6 eV.
We can even search for particles beyond the GZK limit. With the Westerbork telescope we have already set the best limit on cosmic rays and neutrinos above 10^23 eV. With LOFAR we will achieve a much better sensitivity at lower energies, also probing for new physics, like the decays of cosmic strings predicted by supersymmetric theories.
Max ERC Funding
1 500 000 €
Duration
Start date: 2015-06-01, End date: 2020-05-31
Project acronym new-ppd-environments
Project First-principles global MHD disc simulations: Defining planet-forming environments in early solar systems
Researcher (PI) Oliver Lothar Gressel
Host Institution (HI) LEIBNIZ-INSTITUT FUR ASTROPHYSIK POTSDAM (AIP)
Call Details Starting Grant (StG), PE9, ERC-2014-STG
Summary The aim of this ambitious research project is to produce the most realistic computer simulations of gaseous protoplanetary accretion discs to date, and thereby define in an assertive way the environment that shapes the assembly and early evolution of planetary systems.
In their role as planet nurseries, protoplanetary discs are of key interest to planet formation theory. Their dynamical, radiative and thermodynamic properties critically define the environment for embedded solids: dust grains, pebbles and planetesimals. In short, the building blocks of planet formation. The discs’ dynamics and structure in turn depend critically on the influence of magnetic fields that couple to tenuously ionised and low-density regions. Being comparatively cold and dense, the ionisation state of the disc plasma is dominated by external far-UV, X-Ray, and cosmic-ray radiation, leading to a layered vertical structure – with turbulent, magnetised surface layers and a magnetically-decoupled midplane. This classic ‘dead-zone’ picture is now turned upside-down by previously ignored micro-physical effects. For instance, ambipolar diffusion is predicted to dominate in the tenuous hot corona of the disc. It is expected that parts of the disc will thus be stabilised and a magneto-centrifugal wind will be launched. This has so far only been studied in very simplified local models that are affected by fundamental limitations.
Our understanding of the structure of protoplanetary discs is about to undergo a dramatic shift, and my proposed research is at the forefront of this development. My recent successful work at the interface between MHD dynamics and planet formation theory makes me ideally skilled to lead a research group in this endeavour and to communicate advancements to a wide audience of theoreticians in planet formation. Our ambitious global simulations will furthermore provide realistic templates to interpret new observations made with the ALMA telescope array.
Summary
The aim of this ambitious research project is to produce the most realistic computer simulations of gaseous protoplanetary accretion discs to date, and thereby define in an assertive way the environment that shapes the assembly and early evolution of planetary systems.
In their role as planet nurseries, protoplanetary discs are of key interest to planet formation theory. Their dynamical, radiative and thermodynamic properties critically define the environment for embedded solids: dust grains, pebbles and planetesimals. In short, the building blocks of planet formation. The discs’ dynamics and structure in turn depend critically on the influence of magnetic fields that couple to tenuously ionised and low-density regions. Being comparatively cold and dense, the ionisation state of the disc plasma is dominated by external far-UV, X-Ray, and cosmic-ray radiation, leading to a layered vertical structure – with turbulent, magnetised surface layers and a magnetically-decoupled midplane. This classic ‘dead-zone’ picture is now turned upside-down by previously ignored micro-physical effects. For instance, ambipolar diffusion is predicted to dominate in the tenuous hot corona of the disc. It is expected that parts of the disc will thus be stabilised and a magneto-centrifugal wind will be launched. This has so far only been studied in very simplified local models that are affected by fundamental limitations.
Our understanding of the structure of protoplanetary discs is about to undergo a dramatic shift, and my proposed research is at the forefront of this development. My recent successful work at the interface between MHD dynamics and planet formation theory makes me ideally skilled to lead a research group in this endeavour and to communicate advancements to a wide audience of theoreticians in planet formation. Our ambitious global simulations will furthermore provide realistic templates to interpret new observations made with the ALMA telescope array.
Max ERC Funding
1 392 763 €
Duration
Start date: 2015-06-01, End date: 2020-05-31
Project acronym PRIMCHEM
Project Primitive chemistry in planetary atmospheres: From the upper atmosphere down to the surface
Researcher (PI) Nathalie, Marie Carrasco
Host Institution (HI) UNIVERSITE DE VERSAILLES SAINT-QUENTIN-EN-YVELINES.
Call Details Starting Grant (StG), PE9, ERC-2014-STG
Summary The presence of organic compounds was essential to the emergence of life on Earth 3.5 to 3.8 billion years ago. Such compounds may have had several different origins; amongst them the ocean-atmosphere coupled system (the primordial soup theory), or exogenous inputs by meteorites, comets and Interplanetary Dust Particles.
Titan, the largest moon of Saturn, is the best known observable analogue of the Early Earth. I recently identified a totally new source of prebiotic material for this system: the upper atmosphere. Nucleobases have been highlighted as components of the solid aerosols analogues produced in a reactor mimicking the chemistry that occurs in the upper atmosphere. The specificity of this external layer is that it receives harsh solar UV radiations enabling the chemical activation of molecular nitrogen N2, and involving a nitrogen rich organic chemistry with high prebiotic interest.
As organic solid aerosols are initiated in the upper atmosphere of Titan, a new question is raised that I will address: what is the evolution of these organic prebiotic seeds when sedimenting down to the surface? Aerosols will indeed undergo the bombardment of charged particles, further UV radiation, and/or coating of condensable species at lower altitudes. I expect possible changes on the aerosols themselves, but also on the budget of the gas phase through emissions of new organic volatiles compounds. The aerosols aging may therefore impact the whole atmospheric system.
An original methodology will be developed to address this novel issue. The successive aging sequences will be experimentally simulated in chemical reactors combining synchrotron and plasma sources. The interpretation of the experimental results will moreover be supported by a modelling of the processes. This complementary approach will enable to decipher the aerosols evolution in laboratory conditions and to extrapolate the impact on Titan atmospheric system.
Summary
The presence of organic compounds was essential to the emergence of life on Earth 3.5 to 3.8 billion years ago. Such compounds may have had several different origins; amongst them the ocean-atmosphere coupled system (the primordial soup theory), or exogenous inputs by meteorites, comets and Interplanetary Dust Particles.
Titan, the largest moon of Saturn, is the best known observable analogue of the Early Earth. I recently identified a totally new source of prebiotic material for this system: the upper atmosphere. Nucleobases have been highlighted as components of the solid aerosols analogues produced in a reactor mimicking the chemistry that occurs in the upper atmosphere. The specificity of this external layer is that it receives harsh solar UV radiations enabling the chemical activation of molecular nitrogen N2, and involving a nitrogen rich organic chemistry with high prebiotic interest.
As organic solid aerosols are initiated in the upper atmosphere of Titan, a new question is raised that I will address: what is the evolution of these organic prebiotic seeds when sedimenting down to the surface? Aerosols will indeed undergo the bombardment of charged particles, further UV radiation, and/or coating of condensable species at lower altitudes. I expect possible changes on the aerosols themselves, but also on the budget of the gas phase through emissions of new organic volatiles compounds. The aerosols aging may therefore impact the whole atmospheric system.
An original methodology will be developed to address this novel issue. The successive aging sequences will be experimentally simulated in chemical reactors combining synchrotron and plasma sources. The interpretation of the experimental results will moreover be supported by a modelling of the processes. This complementary approach will enable to decipher the aerosols evolution in laboratory conditions and to extrapolate the impact on Titan atmospheric system.
Max ERC Funding
1 487 500 €
Duration
Start date: 2015-09-01, End date: 2021-08-31
