The document discusses detecting dark matter through its annihilation signals across the electromagnetic spectrum. It describes how neutralinos and sterile neutrinos could produce gamma rays, x-rays, and radio emission through various processes. Specific targets are mentioned, including the Galactic center, dwarf galaxies, and galaxy clusters. Future instruments like CTA, SKA, and NuSTAR may help constrain dark matter properties or detect its signals.
PIV EXPERIMENTS ON THE FLOW INDUCED BY A SPHERE SEDIMENTING TOWARDS A SOLID WALLKees Nieuwstad
The motion induced by gravity of solid spheres in a vessel filled with fluid has been investigated experimentally at Reynolds numbers in the range from 1-74 and Stokes numbers ranging from 0.2-17. Trajectories of the spheres have been measured with a focus on start-up behavior, and on impact with a horizontal wall. Two models have been investigated. The first describes the accelerating motion of the sphere. The second model predicts the distance from the wall at which the sphere starts decelerating.
The flow in the vicinity of the sphere was measured by means of PIV. The time scales and flow structures strongly depend on the Reynolds number. Measurements performed are in good agreement with simulations performed at the Kramers Laboratorium.
Automatic high order absorption layers for advective-diffusive systems of equ...Storti Mario
This document discusses automatic higher order absorbing boundary conditions for advective-diffusive systems of equations. It begins by motivating the need for absorbing boundary conditions to prevent non-convergent or unbounded solutions when modeling wave propagation problems. It then reviews existing approaches and their limitations, before proposing a new approach to generate absorbing layers that is automatically computable from the flux function, adjustable to higher orders, and robust. Several example systems where this new approach has been implemented are listed at the end.
Field-flow fractionation (AF4) is a separation technique that uses an external cross-flow to fractionate samples based on differences in size, shape, or density. In AF4, an analyte mixture is injected into a thin channel and separated under the influence of a perpendicular laminar flow. Smaller analytes are eluted faster than larger ones. AF4 coupled with detectors like multi-angle light scattering (MALS) and fluorescence allows characterization of size, shape, and structure of macromolecules, nanoparticles, viruses, liposomes, and protein aggregates with high resolution.
1) Angles can be measured in degrees, minutes, or radians. Trigonometric functions relate to the sides of a right triangle and depend on the angle of rotation.
2) Positive angles are measured clockwise from the positive x-axis, negative angles counterclockwise.
3) The value of a trig function for any angle can be determined using a calculator, right triangles, or trig identities involving reference angles.
The document discusses using an effective field theory (EFT) approach to test general relativity (GR) through gravitational wave detections. It outlines using the EFT method called non-relativistic GR (NRGR) to calculate post-Newtonian corrections and measure deviations from GR. NRGR translates corrections to binary inspiral into Feynman diagrams and provides tools to calculate radiation and conservative dynamics. Measuring the quadrupole formula through detections could probe the non-linearities and vertices of GR.
This document presents an algorithm called Fractional Fourier Transform (FXT) to remove spectral leakage caused by non-coherent sampling of sinewaves. The algorithm works by "twisting" the time/frequency space to accommodate fractional periods. It was shown through simulations and ADC testing to automatically correct for frequency drift, maintain spectral resolution, and conserve SNR. The FXT algorithm allows using non-coherent oscillators for testing applications like ADC or waveform recorders.
PIV EXPERIMENTS ON THE FLOW INDUCED BY A SPHERE SEDIMENTING TOWARDS A SOLID WALLKees Nieuwstad
The motion induced by gravity of solid spheres in a vessel filled with fluid has been investigated experimentally at Reynolds numbers in the range from 1-74 and Stokes numbers ranging from 0.2-17. Trajectories of the spheres have been measured with a focus on start-up behavior, and on impact with a horizontal wall. Two models have been investigated. The first describes the accelerating motion of the sphere. The second model predicts the distance from the wall at which the sphere starts decelerating.
The flow in the vicinity of the sphere was measured by means of PIV. The time scales and flow structures strongly depend on the Reynolds number. Measurements performed are in good agreement with simulations performed at the Kramers Laboratorium.
Automatic high order absorption layers for advective-diffusive systems of equ...Storti Mario
This document discusses automatic higher order absorbing boundary conditions for advective-diffusive systems of equations. It begins by motivating the need for absorbing boundary conditions to prevent non-convergent or unbounded solutions when modeling wave propagation problems. It then reviews existing approaches and their limitations, before proposing a new approach to generate absorbing layers that is automatically computable from the flux function, adjustable to higher orders, and robust. Several example systems where this new approach has been implemented are listed at the end.
Field-flow fractionation (AF4) is a separation technique that uses an external cross-flow to fractionate samples based on differences in size, shape, or density. In AF4, an analyte mixture is injected into a thin channel and separated under the influence of a perpendicular laminar flow. Smaller analytes are eluted faster than larger ones. AF4 coupled with detectors like multi-angle light scattering (MALS) and fluorescence allows characterization of size, shape, and structure of macromolecules, nanoparticles, viruses, liposomes, and protein aggregates with high resolution.
1) Angles can be measured in degrees, minutes, or radians. Trigonometric functions relate to the sides of a right triangle and depend on the angle of rotation.
2) Positive angles are measured clockwise from the positive x-axis, negative angles counterclockwise.
3) The value of a trig function for any angle can be determined using a calculator, right triangles, or trig identities involving reference angles.
The document discusses using an effective field theory (EFT) approach to test general relativity (GR) through gravitational wave detections. It outlines using the EFT method called non-relativistic GR (NRGR) to calculate post-Newtonian corrections and measure deviations from GR. NRGR translates corrections to binary inspiral into Feynman diagrams and provides tools to calculate radiation and conservative dynamics. Measuring the quadrupole formula through detections could probe the non-linearities and vertices of GR.
This document presents an algorithm called Fractional Fourier Transform (FXT) to remove spectral leakage caused by non-coherent sampling of sinewaves. The algorithm works by "twisting" the time/frequency space to accommodate fractional periods. It was shown through simulations and ADC testing to automatically correct for frequency drift, maintain spectral resolution, and conserve SNR. The FXT algorithm allows using non-coherent oscillators for testing applications like ADC or waveform recorders.
The document provides an overview of bonding, molecular vibrations, and lattice vibrations in crystals. It discusses different types of bonding including ionic, covalent, metallic, and secondary bonding. It examines the periodic table and how elements form bonds. It also covers crystal structures, unit cells, X-ray diffraction, and how bonding influences material properties like melting temperature and elastic modulus. Finally, it summarizes vibrational frequencies of molecules and lattice vibrations in crystals using the harmonic approximation.
AACIMP 2010 Summer School lecture by Anton Chizhov. "Physics, Chemistry and Living Systems" stream. "Neuron-Computer Interface in Dynamic-Clamp Experiments. Models of Neuronal Populations and Visual Cortex" course. Part 2.
More info at http://summerschool.ssa.org.ua
Apresentação do professor Pedro Grande, da seção UFRGS do Instituto Nacional de Engenharia de Superfície. Palestra convidada do Simpósio Engenharia de Superfície do X Encontro da SBPMAT. Realizada no dia 26 de setembro de 2011 em Gramado (RS).
1. The document discusses various types of waveguides used to transmit electromagnetic waves, including rectangular waveguides, circular waveguides, coaxial lines, optical waveguides, and parallel-plate waveguides.
2. It describes the properties of parallel-plate waveguides, including their TE and TM modes. The TE modes have the electric field parallel to the plates, while the TM modes have the magnetic field parallel to the plates.
3. Cutoff frequencies are discussed, below which modes do not propagate. The cutoff wavelength is the wavelength at which the phase constant is zero.
Neuron-computer interface in Dynamic-Clamp experimentsSSA KPI
AACIMP 2010 Summer School lecture by Anton Chizhov. "Physics, Chemistry and Living Systems" stream. "Neuron-Computer Interface in Dynamic-Clamp Experiments. Models of Neuronal Populations and Visual Cortex" course. Part 1.
More info at http://summerschool.ssa.org.ua
The document summarizes potential discoveries at the LHC beyond the Standard Model. It discusses:
1) Searches for new constituents like excited neutrinos that may appear as single particles produced via Z, W, or gamma decays.
2) Searches for new quark singlets with charges of -1/3 that could be discovered if pair produced and decaying to bosons and jets.
3) Searches for new up-type quark doublets that could be discovered if pair produced and decaying to W bosons and jets. The document outlines possible mass ranges and luminosities needed for discovery.
4) It notes how new quark discoveries could enhance the search for the Higgs boson
This document discusses trions, which are charged exciton-electron complexes, and their properties. It covers:
1. Trions can exist in singlet or triplet spin states at low electron densities. Modulation doping is used to control electron density in quantum wells.
2. Trions appear in optical spectra and their binding energy depends on the quantum well width. Magnetic fields affect the trion energy levels and allow determination of electron concentration.
3. At high electron densities, combined exciton-electron and trion-electron processes influence photoluminescence spectra. Trion Zeeman splitting also occurs in magnetic fields.
Coercivity weighted Langevin magnetisation: A new approach to interpret super...Dhanesh Rajan
This document summarizes a new approach called "coercivity weighted Langevin magnetization" that more accurately models the superparamagnetic and nonsuperparamagnetic behavior of single domain magnetic nanoparticles. It presents results showing how coercivity and remanence in the single domain regime can be predicted as functions of particle size, temperature, and measurement frequency. The new model combines steady and time-varying magnetization dynamics and considers factors affecting the superparamagnetic state. It defines the transition between superparamagnetic and nonsuperparamagnetic states more precisely and allows direct calculation of coercivity-weighted magnetization and susceptibility.
Simulation of Magnetically Confined Plasma for Etch Applicationsvvk0
The document describes computational optimization of plasma uniformity in a magnetically enhanced capacitively coupled plasma (CCP) reactor for disk etch applications. Initial simulations using a two-dimensional hybrid plasma equipment model (HPEM) showed non-uniform electron density and radical distributions in a CFP plasma with the magnet placed 125 mm from the substrate. The distance between the magnet and substrate was increased to 113 mm, which improved the uniformity of the electron density, CFx radical densities, and plasma potential above the substrate. Further simulations varying the magnet distance found that plasma density and F radical density decreased with smaller magnet-substrate gaps. The study demonstrates optimization of plasma uniformity through computational modeling of magnetic field and plasma transport parameters.
This document discusses quantum theory and the electronic structure of atoms. It begins by introducing properties of waves and electromagnetic radiation. It then covers early discoveries and models in atomic structure, including Planck's quantization of energy, Einstein's explanation of the photoelectric effect using photons, Bohr's model of electron orbits, de Broglie's proposal that electrons exhibit wave-particle duality, and Schrodinger's wave equation describing electron probability distributions. The document concludes by discussing how the Schrodinger equation is used to determine electron configurations and orbital diagrams for atoms.
Talk given at Cambridge DAMTP on Friday, 20 June 2008. Describes recent work on understanding what is necessary to embed accelerating cosmology in higher-dimensional theory.
The document discusses an approach to measuring the electric dipole moment (EDM) of the neutron. It aims to increase the statistical sensitivity to below 10-27 e·cm and systematic sensitivity to below 10-27 e·cm through several methods including increasing UCN density, using a buffer gas to suppress nuclear spin relaxation, using a spherical coil geometry, and implementing various shielding techniques. It also acknowledges collaborators from other institutions. The key ideas are to measure the neutron EDM through Ramsey's method of separated oscillatory fields in a static electric field, and to improve statistical and systematic uncertainties through technical upgrades and experimental design choices.
Spectroscopic ellipsometry is a technique for investigating the optical properties and electrodynamics of materials. It has several advantages over other optical techniques:
1) It provides an exact numerical inversion with no need for Kramers-Kronig transformations, allowing consistency checks.
2) Measurements are non-invasive and highly reproducible as they do not require reference samples.
3) It is very sensitive to thin film properties due to its ability to measure at oblique angles of incidence.
Ellipsometry has been used to study phenomena like superconductivity in cuprates and pnictides by measuring changes in spectral weight, and collective charge ordering in oxide superlattices.
This document summarizes a class lecture on global illumination techniques for computer graphics. It discusses ray tracing and path tracing to solve the rendering equation through Monte Carlo integration. Radiosity for diffuse interreflection using form factors is covered. Participating media and photon mapping are also summarized. The next class will cover acceleration structures to speed up ray tracing computations. Project 4 is assigned, involving implementing a simple ray tracer.
Benchmark Calculations of Atomic Data for Modelling ApplicationsAstroAtom
This document summarizes benchmark calculations of atomic data for modeling applications. It discusses numerical methods like close-coupling and distorted-wave approaches for calculating atomic collision data. It provides selected results on energy levels, oscillator strengths, and electron-impact excitation cross sections. It also discusses applications to modeling neon discharges and takes a closer look at ionization calculations and examples. The document concludes by discussing the production and assessment of atomic data and outlines challenges in obtaining reliable data from both experiments and calculations.
This document discusses machine learning concepts including supervised vs. unsupervised learning, clustering algorithms, and specific clustering methods like k-means and k-nearest neighbors. It provides examples of how clustering can be used for applications such as market segmentation and astronomical data analysis. Key clustering algorithms covered are hierarchy methods, partitioning methods, k-means which groups data by assigning objects to the closest cluster center, and k-nearest neighbors which classifies new data based on its closest training examples.
The document provides an overview of bonding, molecular vibrations, and lattice vibrations in crystals. It discusses different types of bonding including ionic, covalent, metallic, and secondary bonding. It examines the periodic table and how elements form bonds. It also covers crystal structures, unit cells, X-ray diffraction, and how bonding influences material properties like melting temperature and elastic modulus. Finally, it summarizes vibrational frequencies of molecules and lattice vibrations in crystals using the harmonic approximation.
AACIMP 2010 Summer School lecture by Anton Chizhov. "Physics, Chemistry and Living Systems" stream. "Neuron-Computer Interface in Dynamic-Clamp Experiments. Models of Neuronal Populations and Visual Cortex" course. Part 2.
More info at http://summerschool.ssa.org.ua
Apresentação do professor Pedro Grande, da seção UFRGS do Instituto Nacional de Engenharia de Superfície. Palestra convidada do Simpósio Engenharia de Superfície do X Encontro da SBPMAT. Realizada no dia 26 de setembro de 2011 em Gramado (RS).
1. The document discusses various types of waveguides used to transmit electromagnetic waves, including rectangular waveguides, circular waveguides, coaxial lines, optical waveguides, and parallel-plate waveguides.
2. It describes the properties of parallel-plate waveguides, including their TE and TM modes. The TE modes have the electric field parallel to the plates, while the TM modes have the magnetic field parallel to the plates.
3. Cutoff frequencies are discussed, below which modes do not propagate. The cutoff wavelength is the wavelength at which the phase constant is zero.
Neuron-computer interface in Dynamic-Clamp experimentsSSA KPI
AACIMP 2010 Summer School lecture by Anton Chizhov. "Physics, Chemistry and Living Systems" stream. "Neuron-Computer Interface in Dynamic-Clamp Experiments. Models of Neuronal Populations and Visual Cortex" course. Part 1.
More info at http://summerschool.ssa.org.ua
The document summarizes potential discoveries at the LHC beyond the Standard Model. It discusses:
1) Searches for new constituents like excited neutrinos that may appear as single particles produced via Z, W, or gamma decays.
2) Searches for new quark singlets with charges of -1/3 that could be discovered if pair produced and decaying to bosons and jets.
3) Searches for new up-type quark doublets that could be discovered if pair produced and decaying to W bosons and jets. The document outlines possible mass ranges and luminosities needed for discovery.
4) It notes how new quark discoveries could enhance the search for the Higgs boson
This document discusses trions, which are charged exciton-electron complexes, and their properties. It covers:
1. Trions can exist in singlet or triplet spin states at low electron densities. Modulation doping is used to control electron density in quantum wells.
2. Trions appear in optical spectra and their binding energy depends on the quantum well width. Magnetic fields affect the trion energy levels and allow determination of electron concentration.
3. At high electron densities, combined exciton-electron and trion-electron processes influence photoluminescence spectra. Trion Zeeman splitting also occurs in magnetic fields.
Coercivity weighted Langevin magnetisation: A new approach to interpret super...Dhanesh Rajan
This document summarizes a new approach called "coercivity weighted Langevin magnetization" that more accurately models the superparamagnetic and nonsuperparamagnetic behavior of single domain magnetic nanoparticles. It presents results showing how coercivity and remanence in the single domain regime can be predicted as functions of particle size, temperature, and measurement frequency. The new model combines steady and time-varying magnetization dynamics and considers factors affecting the superparamagnetic state. It defines the transition between superparamagnetic and nonsuperparamagnetic states more precisely and allows direct calculation of coercivity-weighted magnetization and susceptibility.
Simulation of Magnetically Confined Plasma for Etch Applicationsvvk0
The document describes computational optimization of plasma uniformity in a magnetically enhanced capacitively coupled plasma (CCP) reactor for disk etch applications. Initial simulations using a two-dimensional hybrid plasma equipment model (HPEM) showed non-uniform electron density and radical distributions in a CFP plasma with the magnet placed 125 mm from the substrate. The distance between the magnet and substrate was increased to 113 mm, which improved the uniformity of the electron density, CFx radical densities, and plasma potential above the substrate. Further simulations varying the magnet distance found that plasma density and F radical density decreased with smaller magnet-substrate gaps. The study demonstrates optimization of plasma uniformity through computational modeling of magnetic field and plasma transport parameters.
This document discusses quantum theory and the electronic structure of atoms. It begins by introducing properties of waves and electromagnetic radiation. It then covers early discoveries and models in atomic structure, including Planck's quantization of energy, Einstein's explanation of the photoelectric effect using photons, Bohr's model of electron orbits, de Broglie's proposal that electrons exhibit wave-particle duality, and Schrodinger's wave equation describing electron probability distributions. The document concludes by discussing how the Schrodinger equation is used to determine electron configurations and orbital diagrams for atoms.
Talk given at Cambridge DAMTP on Friday, 20 June 2008. Describes recent work on understanding what is necessary to embed accelerating cosmology in higher-dimensional theory.
The document discusses an approach to measuring the electric dipole moment (EDM) of the neutron. It aims to increase the statistical sensitivity to below 10-27 e·cm and systematic sensitivity to below 10-27 e·cm through several methods including increasing UCN density, using a buffer gas to suppress nuclear spin relaxation, using a spherical coil geometry, and implementing various shielding techniques. It also acknowledges collaborators from other institutions. The key ideas are to measure the neutron EDM through Ramsey's method of separated oscillatory fields in a static electric field, and to improve statistical and systematic uncertainties through technical upgrades and experimental design choices.
Spectroscopic ellipsometry is a technique for investigating the optical properties and electrodynamics of materials. It has several advantages over other optical techniques:
1) It provides an exact numerical inversion with no need for Kramers-Kronig transformations, allowing consistency checks.
2) Measurements are non-invasive and highly reproducible as they do not require reference samples.
3) It is very sensitive to thin film properties due to its ability to measure at oblique angles of incidence.
Ellipsometry has been used to study phenomena like superconductivity in cuprates and pnictides by measuring changes in spectral weight, and collective charge ordering in oxide superlattices.
This document summarizes a class lecture on global illumination techniques for computer graphics. It discusses ray tracing and path tracing to solve the rendering equation through Monte Carlo integration. Radiosity for diffuse interreflection using form factors is covered. Participating media and photon mapping are also summarized. The next class will cover acceleration structures to speed up ray tracing computations. Project 4 is assigned, involving implementing a simple ray tracer.
Benchmark Calculations of Atomic Data for Modelling ApplicationsAstroAtom
This document summarizes benchmark calculations of atomic data for modeling applications. It discusses numerical methods like close-coupling and distorted-wave approaches for calculating atomic collision data. It provides selected results on energy levels, oscillator strengths, and electron-impact excitation cross sections. It also discusses applications to modeling neon discharges and takes a closer look at ionization calculations and examples. The document concludes by discussing the production and assessment of atomic data and outlines challenges in obtaining reliable data from both experiments and calculations.
This document discusses machine learning concepts including supervised vs. unsupervised learning, clustering algorithms, and specific clustering methods like k-means and k-nearest neighbors. It provides examples of how clustering can be used for applications such as market segmentation and astronomical data analysis. Key clustering algorithms covered are hierarchy methods, partitioning methods, k-means which groups data by assigning objects to the closest cluster center, and k-nearest neighbors which classifies new data based on its closest training examples.
- The document discusses methods for characterizing dark energy and modified gravity models in a model-independent way using cosmological observations.
- Due to the "dark degeneracy" between dark matter and dark energy, it is not possible to separately measure the properties of dark matter and dark energy without assuming a specific model class.
- Observables like the Hubble parameter H(z) and gravitational potentials can be reconstructed from the data, but this does not break the degeneracy between dark matter and dark energy contributions.
- The scale-dependence of quantities like the gravitational potentials and growth rate can be used to test and constrain broad classes of dark energy and modified gravity models in a more model-independent way.
Seminar by Prof Bruce Bassett at IAP, Paris, October 2013CosmoAIMS Bassett
This document discusses the rise of machine learning and artificial intelligence in astronomy due to a massive increase in data from upcoming surveys. It will produce around an exabyte of data per day, far more than has been produced throughout human history. This raises issues around preparing students, and how science may be done. The document discusses using machine learning for tasks like supernova identification and classification. It also discusses challenges like ensuring machine learning results are trustworthy, and whether this can truly replace human genius. It explores the idea of a universal language for scientific theories that could be searched algorithmically.
The 21cm line from neutral hydrogen can be used to study cosmology during the first billion years of the universe. This includes the Dark Ages when no structures formed, the Cosmic Dawn when the first luminous objects formed, and the Epoch of Reionization when these objects reionized the intergalactic medium. Current and future 21cm experiments like LOFAR, MWA, PAPER, and HERA aim to detect the signal from these eras but face challenges in calibrating the instruments and subtracting bright foreground sources. Some progress has been made in placing upper limits on the signal and constraining the heating of the intergalactic medium by X-rays, but a clear detection of the signal is still needed
The document discusses the cosmic dawn and reionization period in the early universe. It describes the evolution from the dark ages after recombination to the epoch of reionization around z=6-20. Key aspects discussed include understanding the sources and sinks of ionizing photons that drove reionization, and challenges in modeling this period due to the large parameter space and scales involved, from single stars to the entire universe. Seminumerical simulations are presented as an efficient method to model reionization and predict 21cm signals.
A short introduction to massive gravity... or ... Can one give a mass to the ...CosmoAIMS Bassett
1. The document discusses massive gravity and proposes that giving the graviton a small mass could potentially explain dark matter and dark energy without needing to introduce those concepts.
2. It reviews several models of massive gravity, including the Dvali-Gabadadze-Porrati model, which produces cosmic acceleration similar to dark energy. Kaluza-Klein theory is also discussed as producing massive gravitons.
3. Nonlinear extensions of the Pauli-Fierz theory are examined, finding solutions only with singularities. The "Goldstone" description of massive gravity is introduced as a way to better understand nonlinear effects like the Vainshtein mechanism.
This document summarizes recent research on how the sizes and densities of galaxies have changed over time. Studies have found that galaxies at high redshift had smaller sizes than present-day galaxies of the same mass, often by a factor of 2-3 within 1 kpc and over 100 times within the effective radius. Various mechanisms are discussed for how galaxies could have grown, including minor mergers which could increase size more than mass over time. The document also examines constraints on the amount of growth massive galaxies could have experienced through mergers between redshifts of 0.8 to 0.1 based on the luminosity and stellar mass functions remaining largely unchanged over this period.
Cluster abundances and clustering Can theory step up to precision cosmology?CosmoAIMS Bassett
This document discusses improvements to the Press-Schechter theory for modeling the abundances and clustering of dark matter halos. It proposes that modeling halo collapse as requiring the density to "step up" above a critical density threshold at progressively larger spatial scales provides a better approximation than assuming fully correlated or uncorrelated densities. This "stepping up" approach requires only 2-point statistics and can be applied to non-Gaussian fields. The document also suggests that modeling the distribution of density slopes at peak positions provides a way to match halo counts through an Excursion Set Peaks model.
This document discusses gravitational lensing and some of the challenges involved in measuring it. Gravitational lensing causes the apparent deflection of light from distant background sources as it passes massive foreground objects. Precise measurements of lensing effects can provide information about dark matter distributions and the geometry and growth of the universe. However, there are three main problems: accurately measuring galaxy shapes used to detect lensing distortions, determining reliable photometric redshifts for galaxies, and accounting for intrinsic alignments of galaxy orientations unrelated to lensing.
Testing cosmology with galaxy clusters, the CMB and galaxy clusteringCosmoAIMS Bassett
This document summarizes a presentation on testing cosmology using galaxy clusters, the cosmic microwave background, and galaxy clustering. It discusses combining measurements of cosmic growth and expansion from these sources to constrain departures from general relativity. Models are presented for linear, time-dependent departures from GR. Constraints on parameters like the growth index γ are shown from combinations of clusters, CMB, and galaxy data. Tightening constraints are achieved by adding baryon acoustic oscillation, supernova, and Hubble constant data. The document also briefly discusses using cluster counts to constrain primordial non-Gaussianity.
This document discusses galaxy formation and evolution from cosmological simulations and models. It summarizes that galaxy formation is driven by the hierarchical growth of dark matter halos, gas accretion via cold filamentary streams or hot spherical halos, and feedback regulating star formation. Galaxy properties like star formation rates and metallicities are set by the balance between gas inflow and outflow.
Spit, Duct Tape, Baling Wire & Oral Tradition: Dealing With Radio DataCosmoAIMS Bassett
The document discusses the process of creating radio interferometers and summarizing data from them. It begins with an overview of how a normal reflector telescope can be broken up and transformed into an interferometer by replacing the optical path with electronics and correlating signals between antenna elements. It then discusses some of the challenges in summarizing interferometer data, including missing information due to an incomplete coverage of the uv-plane, measurement errors that distort the signals, and direction-dependent effects that vary with time, antenna, and direction. The document introduces the concept of the Radio Interferometer Measurement Equation (RIME) to formally describe these direction-dependent distortions.
The document summarizes the MeerKAT radio telescope project in South Africa, including:
- MeerKAT will be the largest radio telescope in the southern hemisphere and one of the largest in the world, establishing a legacy for Africa. It is an SKA precursor project.
- The specifications for MeerKAT including the number of antennas, maximum baseline, bandwidth, frequency range, and survey plans.
- MeerKAT will initially consist of 64 antennas in 2016, expanding over time. It aims to carry out a number of surveys for HI, pulsars, galaxies, and fast/slow transients.
- Opportunities are outlined for students and faculty to get involved in radio astronomy research
This document provides guidance on reducing interferometric radio astronomy data from the Karoo Array Telescope (KAT-7) using the Common Astronomy Software Applications (CASA). It describes the multi-step process of calibration and imaging required to produce an image from the visibility measurements made by an interferometer. The key steps involve: 1) converting the raw data from HDF5 format to a measurement set, 2) loading and inspecting the data, 3) flagging bad or corrupted data, 4) solving for the complex gain calibration terms using calibrator sources, 5) splitting the data for source and calibrator, 6) deconvolving the dirty image using CLEAN to account for incomplete uv-coverage. Trouble
From Darkness, Light: Computing Cosmological ReionizationCosmoAIMS Bassett
1) Reionization occurred between redshifts of 10-6, beginning around 10 billion years ago and ending around 1 billion years ago.
2) Observations of the CMB and galaxies at z>6 provide constraints but questions remain about the sources and topology of reionization.
3) Cosmological simulations of reionization must model structure formation, radiation transport, and non-equilibrium chemistry and physics to help address open questions.
WHAT CAN WE DEDUCE FROM STUDIES OF NEARBY GALAXY POPULATIONS?CosmoAIMS Bassett
Studies of nearby galaxy populations using large optical surveys like SDSS have provided insights into galaxy formation and evolution. Key findings include identifying characteristic scales where baryon conversion peaks at halo masses of ~10^12 solar masses and galaxies transition from blue to red at stellar masses of ~10^10 solar masses. While surveys have constrained stellar populations and traced dark matter halos, they have not well constrained gas accretion onto galaxies, gas outflows, or the influence of black holes on galaxy evolution.
Binary pulsars provide an excellent tool to test theories of gravity. The document describes several binary pulsar systems and how measurements of their orbital parameters over time have allowed for high-precision tests of general relativity in strong gravitational fields. Specifically, the double pulsar system PSR J0737-3039A/B has enabled measurements that agree with general relativity predictions to within 0.05% precision by measuring parameters like periastron advance and gravitational redshift effects.
Cross Matching EUCLID and SKA using the Likelihood RatioCosmoAIMS Bassett
1) The document discusses using a likelihood ratio technique to identify counterparts between low-resolution radio data from surveys like SKA and optical/infrared data from surveys like Euclid.
2) The likelihood ratio technique calculates probabilities that potential counterparts are true matches versus random alignments based on positional offsets and magnitude distributions.
3) Applying the technique to simulated lower-resolution radio data shows a 3-5% loss in identified counterparts compared to high-resolution data, with the worst effects for faint radio sources. However, the vast majority of identified counterparts remain the same.
The document discusses using machine learning techniques to classify astronomical objects from large surveys. It notes that surveys are producing huge amounts of data that conventional methods cannot fully process. Machine learning can be used to help classify objects and sort candidates. Specifically, the document discusses using machine learning on photometric data from the Sloan Digital Sky Survey (SDSS) to identify low-redshift quasars. It notes challenges including the large size and dimensionality of the data, and proposes using a boosted ensemble method to learn weights for different regions of feature space rather than trying to estimate probabilities. This would help classify objects from the SDSS into categories like quasars, stars or galaxies.
What is an RPA CoE? Session 2 – CoE RolesDianaGray10
In this session, we will review the players involved in the CoE and how each role impacts opportunities.
Topics covered:
• What roles are essential?
• What place in the automation journey does each role play?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
GlobalLogic Java Community Webinar #18 “How to Improve Web Application Perfor...GlobalLogic Ukraine
Під час доповіді відповімо на питання, навіщо потрібно підвищувати продуктивність аплікації і які є найефективніші способи для цього. А також поговоримо про те, що таке кеш, які його види бувають та, основне — як знайти performance bottleneck?
Відео та деталі заходу: https://bit.ly/45tILxj
"Choosing proper type of scaling", Olena SyrotaFwdays
Imagine an IoT processing system that is already quite mature and production-ready and for which client coverage is growing and scaling and performance aspects are life and death questions. The system has Redis, MongoDB, and stream processing based on ksqldb. In this talk, firstly, we will analyze scaling approaches and then select the proper ones for our system.
"NATO Hackathon Winner: AI-Powered Drug Search", Taras KlobaFwdays
This is a session that details how PostgreSQL's features and Azure AI Services can be effectively used to significantly enhance the search functionality in any application.
In this session, we'll share insights on how we used PostgreSQL to facilitate precise searches across multiple fields in our mobile application. The techniques include using LIKE and ILIKE operators and integrating a trigram-based search to handle potential misspellings, thereby increasing the search accuracy.
We'll also discuss how the azure_ai extension on PostgreSQL databases in Azure and Azure AI Services were utilized to create vectors from user input, a feature beneficial when users wish to find specific items based on text prompts. While our application's case study involves a drug search, the techniques and principles shared in this session can be adapted to improve search functionality in a wide range of applications. Join us to learn how PostgreSQL and Azure AI can be harnessed to enhance your application's search capability.
Northern Engraving | Nameplate Manufacturing Process - 2024Northern Engraving
Manufacturing custom quality metal nameplates and badges involves several standard operations. Processes include sheet prep, lithography, screening, coating, punch press and inspection. All decoration is completed in the flat sheet with adhesive and tooling operations following. The possibilities for creating unique durable nameplates are endless. How will you create your brand identity? We can help!
How information systems are built or acquired puts information, which is what they should be about, in a secondary place. Our language adapted accordingly, and we no longer talk about information systems but applications. Applications evolved in a way to break data into diverse fragments, tightly coupled with applications and expensive to integrate. The result is technical debt, which is re-paid by taking even bigger "loans", resulting in an ever-increasing technical debt. Software engineering and procurement practices work in sync with market forces to maintain this trend. This talk demonstrates how natural this situation is. The question is: can something be done to reverse the trend?
AI in the Workplace Reskilling, Upskilling, and Future Work.pptxSunil Jagani
Discover how AI is transforming the workplace and learn strategies for reskilling and upskilling employees to stay ahead. This comprehensive guide covers the impact of AI on jobs, essential skills for the future, and successful case studies from industry leaders. Embrace AI-driven changes, foster continuous learning, and build a future-ready workforce.
Read More - https://bit.ly/3VKly70
QR Secure: A Hybrid Approach Using Machine Learning and Security Validation F...AlexanderRichford
QR Secure: A Hybrid Approach Using Machine Learning and Security Validation Functions to Prevent Interaction with Malicious QR Codes.
Aim of the Study: The goal of this research was to develop a robust hybrid approach for identifying malicious and insecure URLs derived from QR codes, ensuring safe interactions.
This is achieved through:
Machine Learning Model: Predicts the likelihood of a URL being malicious.
Security Validation Functions: Ensures the derived URL has a valid certificate and proper URL format.
This innovative blend of technology aims to enhance cybersecurity measures and protect users from potential threats hidden within QR codes 🖥 🔒
This study was my first introduction to using ML which has shown me the immense potential of ML in creating more secure digital environments!
This talk will cover ScyllaDB Architecture from the cluster-level view and zoom in on data distribution and internal node architecture. In the process, we will learn the secret sauce used to get ScyllaDB's high availability and superior performance. We will also touch on the upcoming changes to ScyllaDB architecture, moving to strongly consistent metadata and tablets.
"What does it really mean for your system to be available, or how to define w...Fwdays
We will talk about system monitoring from a few different angles. We will start by covering the basics, then discuss SLOs, how to define them, and why understanding the business well is crucial for success in this exercise.
[OReilly Superstream] Occupy the Space: A grassroots guide to engineering (an...Jason Yip
The typical problem in product engineering is not bad strategy, so much as “no strategy”. This leads to confusion, lack of motivation, and incoherent action. The next time you look for a strategy and find an empty space, instead of waiting for it to be filled, I will show you how to fill it in yourself. If you’re wrong, it forces a correction. If you’re right, it helps create focus. I’ll share how I’ve approached this in the past, both what works and lessons for what didn’t work so well.
Essentials of Automations: Exploring Attributes & Automation ParametersSafe Software
Building automations in FME Flow can save time, money, and help businesses scale by eliminating data silos and providing data to stakeholders in real-time. One essential component to orchestrating complex automations is the use of attributes & automation parameters (both formerly known as “keys”). In fact, it’s unlikely you’ll ever build an Automation without using these components, but what exactly are they?
Attributes & automation parameters enable the automation author to pass data values from one automation component to the next. During this webinar, our FME Flow Specialists will cover leveraging the three types of these output attributes & parameters in FME Flow: Event, Custom, and Automation. As a bonus, they’ll also be making use of the Split-Merge Block functionality.
You’ll leave this webinar with a better understanding of how to maximize the potential of automations by making use of attributes & automation parameters, with the ultimate goal of setting your enterprise integration workflows up on autopilot.
Session 1 - Intro to Robotic Process Automation.pdfUiPathCommunity
👉 Check out our full 'Africa Series - Automation Student Developers (EN)' page to register for the full program:
https://bit.ly/Automation_Student_Kickstart
In this session, we shall introduce you to the world of automation, the UiPath Platform, and guide you on how to install and setup UiPath Studio on your Windows PC.
📕 Detailed agenda:
What is RPA? Benefits of RPA?
RPA Applications
The UiPath End-to-End Automation Platform
UiPath Studio CE Installation and Setup
💻 Extra training through UiPath Academy:
Introduction to Automation
UiPath Business Automation Platform
Explore automation development with UiPath Studio
👉 Register here for our upcoming Session 2 on June 20: Introduction to UiPath Studio Fundamentals: https://community.uipath.com/events/details/uipath-lagos-presents-session-2-introduction-to-uipath-studio-fundamentals/
In the realm of cybersecurity, offensive security practices act as a critical shield. By simulating real-world attacks in a controlled environment, these techniques expose vulnerabilities before malicious actors can exploit them. This proactive approach allows manufacturers to identify and fix weaknesses, significantly enhancing system security.
This presentation delves into the development of a system designed to mimic Galileo's Open Service signal using software-defined radio (SDR) technology. We'll begin with a foundational overview of both Global Navigation Satellite Systems (GNSS) and the intricacies of digital signal processing.
The presentation culminates in a live demonstration. We'll showcase the manipulation of Galileo's Open Service pilot signal, simulating an attack on various software and hardware systems. This practical demonstration serves to highlight the potential consequences of unaddressed vulnerabilities, emphasizing the importance of offensive security practices in safeguarding critical infrastructure.
The Microsoft 365 Migration Tutorial For Beginner.pptxoperationspcvita
This presentation will help you understand the power of Microsoft 365. However, we have mentioned every productivity app included in Office 365. Additionally, we have suggested the migration situation related to Office 365 and how we can help you.
You can also read: https://www.systoolsgroup.com/updates/office-365-tenant-to-tenant-migration-step-by-step-complete-guide/
What is an RPA CoE? Session 1 – CoE VisionDianaGray10
In the first session, we will review the organization's vision and how this has an impact on the COE Structure.
Topics covered:
• The role of a steering committee
• How do the organization’s priorities determine CoE Structure?
Speaker:
Chris Bolin, Senior Intelligent Automation Architect Anika Systems
Conversational agents, or chatbots, are increasingly used to access all sorts of services using natural language. While open-domain chatbots - like ChatGPT - can converse on any topic, task-oriented chatbots - the focus of this paper - are designed for specific tasks, like booking a flight, obtaining customer support, or setting an appointment. Like any other software, task-oriented chatbots need to be properly tested, usually by defining and executing test scenarios (i.e., sequences of user-chatbot interactions). However, there is currently a lack of methods to quantify the completeness and strength of such test scenarios, which can lead to low-quality tests, and hence to buggy chatbots.
To fill this gap, we propose adapting mutation testing (MuT) for task-oriented chatbots. To this end, we introduce a set of mutation operators that emulate faults in chatbot designs, an architecture that enables MuT on chatbots built using heterogeneous technologies, and a practical realisation as an Eclipse plugin. Moreover, we evaluate the applicability, effectiveness and efficiency of our approach on open-source chatbots, with promising results.
QA or the Highway - Component Testing: Bridging the gap between frontend appl...zjhamm304
These are the slides for the presentation, "Component Testing: Bridging the gap between frontend applications" that was presented at QA or the Highway 2024 in Columbus, OH by Zachary Hamm.
QA or the Highway - Component Testing: Bridging the gap between frontend appl...
Colafrancesco - Dark Matter Dectection 2
1. CTICS 2012 Jan 25th, 2012
Dark Matter detection (2)
Sergio Colafrancesco
Wits University - DST/NRF SKA Research Chair
INAF - OAR
Email: Sergio.Colafrancesco@wits.ac.za
Email
Sergio.Colafrancesco@oa-roma.inaf.it
1
2. Outline
Multi-epoch
The Dark Matter Timeline
The present
Multi-Scale + M3
Galactic center
Galactic structures
Galaxy Clusters
The Future
The DM search challenge
2
3. Viable DM candidates: signals
Neutralinos Sterile ν’s
Annihilation Radiative decay: line
νs → να + γ
DM annihilation flux DM decay flux
1 ρ DM ( r )
2
1 ρ DM ( r )
F ∝ 2 2
〈σ V 〉 Astro physics F ∝ 2
〈 Γ rad 〉
DL Mχ DL Mv
dE
× [ f ann ( E ; χ )] Particle physics [ ]
dE
× Eγ ( M v )
dν dν
3
4. Viable DM candidates: signals
Neutralinos Sterile ν’s
Annihilation Radiative decay: line
νs → να + γ
Ms
Inverse Compton scattering
π0 Mχ
Synchr.
Particle physics
Bremsstrahlung
4
6. High frequency
X-rays p
bremsstrahlung
Ha oces
Ha ces
ICS
prr
po
drr se
γ+γ
d o se
γCMB e± π0
on s
niic s
c
Le
Le
π± χ
pt
pt
on
on
χ p Gamma rays
iic
e±
cp
(π0 decay)
e±
pr
e±
ro
γCMB
oc
cees
Gamma rays
ssse
bremsstrahlung
es
Low frequency B
s
ICS
Radio emission SZ effect
ICS
Synchrotron 6
7. Covering the whole e.m. spectrum
χχ
annihilation
products
Br Br
on e e m
t
tr
fec
o m .+
hr .+ IC
Ef
IC S
c IC S+
IC
yn S π0
SZ
S
S
7
8. Leptons: e± equilibrium spectrum
∂ ne ( E , r ) ∂
− ∇ [ D( E )∇ ne ( E , r )] − [ be ( E )ne ( E , r )] = Qe ( E , r )
∂t ∂E
Production Equilibrium
Qe ( E , r ) ne ( E , r )
Diffusion E losses
D( E ) = D0 E γ B − γ be ( E ) = bIC + bsync + bCoul + bbrem
8
9. Solution: complete
Mχ
1 ˆ
ne ( E , r ) =
b( E ) ∫
E
dE ′G (r , λ − λ ′ )Qe ( E , r )
NFW04
Galaxy clusters
Galaxies
(r ′ ) 2 (rn′ + r ) 2 nχ (r ′ )
Rh 2
1 +∞
(r ′ − rn ) 2
ˆ=
G
[4π ∆ λ ]1/ 2
∑− ∞ (− 1) n ∫ dr ′ ' exp −
rn r 4∆ λ
− exp −
2
4 ∆ λ nχ ( r )
n= 0
[Colafrancesco, Profumo & Ullio 2006-2007] 9
10. Energy losses vs. Diffusion
2
E Rh
τ loss = τ D =
b( E , B, nth ) D( E )
B increase nth decrease
Rh decrease
10
11. Solution: qualitative
Vsource τD
ne ( E , r ) = [ Qe ( E , r )τ loss ] ⋅ ⋅
Vsource + Vdiffusion τ D + τ loss
VD VD
Vs Vs
τ loss « τ D τ loss » τ D
Vsource τ D
ne ( E , r ) = [ Qe ( E , r )τ loss ] ne ( E , r ) = [ Qe ( E , r )τ loss ] ⋅ ⋅
Vdiffusion τ loss
Galaxy clusters Galaxies 11
12. Neutralino DM: SED
−8
τ π ± ≈ 2.6 ⋅ 10 s Synch. ICS on CMB π0 decay τ 0 ≈ 8.4 ⋅ 10− 17 s
π
Coma DUAL
Mχ=40 GeV Fermi
_
bb
CTA
NuSTAR
Secondary products Prompt
leptons hadrons
.
.
10-30-31 ←SKA (1GHz) 12
17. The Galactic Center
Multi-ν
Galactic center region across the spectrum:
red: radio 90 cm (VLA); green: mid-infrared; blue: X-ray (1-8 keV; Chandra ACIS-I)
17
18. The Galactic Center: a close up
Galactic Center (Survey) Multiwavelength Close-Up
A multiwavelength close-up of the recent massive star-forming region near the Galactic center.
The color image, plotted also in standard Galactic coordinates, is a composite of 20-cm radio
continuum (red); 25-µm mid-infrared (green); and 6.4-keV line emission (blue). 18
19. Galactic Center demography
Crowded, active environment
HESS CTA
Fermi (1GeV)
EGRET source
Central Black Hole
X-ray source SNR Sgr A East non-thermal filaments (radio)
19
20. The GC region DM challenge
Gondolo 1998
Gondolo & Silk 1999
…
Cesarini et al. 2003
…
De Boer et al. 2005
…
Hooper et al. 2008
…
Borriello et al. 2008
Regis & Ullio 2008
Crocker et al. 2010
Sgr-A SED in quiescent radio + X-ray stage
[Regis & Ullio 2008]
20
21. The GC region DM challenge: limits
Constraints from radio + γ-rays
• Radio: constrain to ~ GeV-TeV mass
• γ-rays: constrain to ≤ GeV mass
• ν’s : constrain to > 10 TeV mass
Borriello et al. 2008
Radio + EGRET
[Crocker et al. 2010]
Radio + HESS
[Regis & Ullio 2008]
21
22. The GC region DM challenge: limits
Fermi-LAT results on the diffuse γ-ray emission improves DM limits
→ by a factor ~ 20-50
[Abazajian et al. 2010]
Caveats
• modelling of diffuse foregrounds (Galactic, Extra-Galactic)
• unresolved point-like sources (PSR, MCs, AGNs, Starburst gal., Clusters, GRBs,..)
• data analysis techniques (Likelihood vs. photon counts) 22
23. The GC region DM challenge: HESS
Search for a DM annihilation signal
from the Galactic Center halo with
H.E.S.S. (arXiv:1103.3266v)
Thermal Dark Matter
23
24. The GC region DM challenge
Strongest constraints from SKA + CTA
• Radio: constrain to ~ GeV-TeV mass
• γ-rays: constrain to ~ GeV-TeV mass VLA
• ν’s : constrain to > 10 TeV mass
T
G RE
io +E
Rad ES
S
o +H
R adi
S
H ES
+
K AT
M eer
SKA CTA
P1 C TA
-28 A +
SK P2
A
SK
-29 24
25. The GC region DM challenge: uncertainties
B-field at GC
• from 4 to 1000 µG
• > 50µG (radio + γ-rays)
[Crocker et al. 2010]
Diffusion
DM density profile
DM dynamics at GC
DM vs. BH
Astrophysical sources
[Regis & Ullio 2008]
Stationary & Transient
25
26. The GC Haze
Radio emission due to secondary e±
is spatially extended (ν-dependent)
Radio halo (haze)
RH size decreases with increasing ν
ICS emission due to secondary e±
is spatially extended (ν-dependent)
IC halo (haze)
ICH size decreases with increasing ν
The angular size for the equilibrium n.
density of high-E e± is much broader
than the γ-ray flux from π0 decays
π0 halo (haze) = DM source
πH size smaller than RH / ICH size 26
27. WMAP vs. Fermi haze
Cosmic ray electrons interacting
with the Galactic magnetic field
cosmic ray electrons interacting
with the ISRF to produce ICS
27
28. GC hazes: puzzles or certainties
Dark Matter
- DM (W±,bb) is not the
origin of Fermi haze
- DM (e±) can fit the
Fermi haze with a
boost factor ~ 100 DM prediction Fermi data
→ multi-ν problems Galprop (Dobler et al. 2009)
ms Pulsars
- 50 % energy
conversion in e±
- 30,000 msP in GC
- msP not resolved
in radio and gamma.
→ Haze of unresolved [Malyshev et al. 2010]
point-like sources 28
36. The Dwarf Galaxies DM challenge
Vsource τD
Sub-galactic size systems ne ( E , r ) = [ Qe ( E , r )τ loss ] ⋅ ⋅
- R ~ kpc Vsource + Vdiffusion τ D + τ loss
- No gas
- Little dust VD
- No Crs
- 1 (or 2) stellar populations Vs
- M/L ~ 500 - 3500
τ loss » τ D
+ Ideal systems to probe DM
Vsource τ D
+ Clean multi-ν features ne ( E , r ) = [ Qe ( E , r )τ loss ] ⋅ ⋅
Vdiffusion τ loss
but…
Iν
- Strong diffusion effects
- Low signals r
36
37. Dwarf Sph. galaxies & DM constraints
σv VD
I (ν ) ∝ B ⊗ De ⊗ n ( Ee ,ν , r ) 2
2
e
Mχ
VS
γ
De = D0 ( Ee / B)
Spectrum
B χ Brightness
37
38. ATCA → MeerKAT → SKA
ATCA
MeerKAT
SKA
ATCA MeerKAT
SKA
38
39. Dark Matter search @ radio
121.5 hr @ ATCA
to observe 6 dwarf galaxies
[S.C. et al. 2011]
Constraints on DM parameter space
Segue-3 Carina
Fermi 2yr
ATCA 121hr
MeerKAT
SKA-P1
39
40. Expectations: the HXR range
Normalization fixed by the lack of HXR and radio profiles are different
detection in ATCA (F1.3GHz < 10µJy) HXR and –ray profiles are similar
σV=4 10-28 cm3/s
Draco
σV=4 10-28 cm3/s
0.1µG π0
ICS
Synch
1µG no diff
diff
ATCA
NuSTAR DUAL
40
41. SZE from DM annihilation
Inverse Compton Scattering
∆ TCMB
of CMB photons ≈ g ( x; M χ ) ⋅ ∫ d ⋅ Pe
by secondary DM electrons TCMB
DM halo
SKA-P2 (0.1-45 GHz)
MeerKAT (0.7-30 GHz)
• Measure radio (low ν) & ICS emission (high ν) from DM halos
• Disentangle electron population and B-field → Fradio/FICS = UB/UCMB
41
•
56. Clusters of galaxies
Integrated spectrum Brightness distribution
(30 MHz-5 GHz) (@ 1.4 GHz)
I (ν ) ∝ B ⊗ De ⊗ ne2 ( Ee ,ν , r ) σ v B S (ν ) ∝ B ⊗ De ⊗ ne2 ( Ee ,ν , r ) σ v
Coma
χ su
b-h
alo
s
[Colafrancesco, Profumo & Ullio 2006] 56
57. Galaxy clusters: DM challenge
Baryons + Cosmic Rays
Dark Matter
DM only CRs only
57
59. A Dark Temptation
Explain HXR in cluster as DM annihilation signals
A3627 More than 20 clusters with Hard X-ray excess
at E> 20 keV (Swift-BAT data, BeppoSAX data)
Equally fit with:
- Two temperature (thermal) plasma
- Thermal plasma + non-thermal power-law
AGN emission or ICS from DM / CR interaction
OPHIUCHUS
59
61. DM & heating
DM models that fit the HXR flux
of galaxy clusters produce also
an excess heating of the gas.
Heating ICS
DM annih. heating
Th. Brem. cooling
[Colafrancesco & Marchegiani 2009] 61
62. Dark temptations never go away...
Normalized to F(E> 0.1 GeV) Possible detection for texp> 4Msec
[Jeltema & Profumo arXiv:1108.1407]
62
63. HXR – Gamma vs. HXR - Radio
Normalized to F(ν=1.4GHz) GeV experiments are far from
With known B=5µG DM signal detections
σV=7·10-21 cm3/s σV=10-25 cm3/s
5µG
5µG
1µG
1µG
0.2µG
0.2µG
HXR – Radio correlation provides stronger constraints on DM
(MeerKAT/SKA vs. NuSTAR/DUAL combined obs. @ Wits University)
63
64. DM signal profiles: HXR-Radio-gamma
A2163 Hydra
σV=7·10-21 cm3/s σV=10-25 cm3/s
Sπ0(1 GeV) Sπ0(1 GeV)
SICS(50 keV) Ssynch(1.4 GHz) SICS(50 keV)
Ssynch(1.4 GHz)
B=5 µG B=1 µG
NuSTAR DUAL NuSTAR DUAL
There is a spatial signature of DM signals visible in the HXRs
Clear HXR-radio correlations at large angular scales (> 1 arcmin)
No clear HXR-gamma correlation at all angular scales 64
65. DM & γ-rays: Fermi limits
Neutralino upper limits from 2 recent preprints:
Q.Yuan et al. 2010 (arXiv:1002.0197)
Fermi-LAT collaboration 2010 (arXiv:1002.2239)
no substructures substructures
… but very optimistic upper limits (no CRs, no AGNs, no gal.,65…)
66. DM models & non-thermal phenomena
Coma Coma Coma
CTA CTA CTA
SKA SKA SKA
66
69. Modelling the Perseus cluster
RG (3C84)
Mini RH
Sy 1.5 NGC1275
Blazar Blazar
core
1
2 3
[Colafrancesco et al. 2010]] 69
70. DM @ γ-rays: disentangling CRs, AGN, DM
Possibility to detect γ-rays from Perseus
• in low-states of the central AGN
• in the outer parts of the cluster (>780kpc)
Perseus + NGC1275
[Colafrancesco & Marchegiani 2010]
[Abdo et al.+S.C. 2009]
heating high
DM
low
70
73. Exploring DM universes
Direct
Detection
Techniques
p-χ cross-section
9 orders
of mag. in
direct detection
cross-section
usually
not shown
Neutralino χ mass 73
74. Exploring DM universes
Direct
Detection
Underground detectors
SKA CTA Fermi Astrophysics
Indirect Detection
74
75. Exploring DM universes
Direct
DM detectors + Astrophysics LHC + Astrophysics
Detection
SKA
SKA CTA Fermi
Indirect Detection 75
78. Sterile neutrinos: limits
d ed
lu
E xc
Excluded by Ly-α
Bullet cluster
[Watson et al. 2006 (astro-ph/0605424)]
[Colafrancesco 2007] 78
79. [Yuksel et al. 2007]
[Colafrancesco 2007]
DUAL
NHXM Coma constraints from
20-80 keV emission
NEXT
nuStar
79
80. Sterile neutrinos and GC lines
Fact:
Excess of the intensity in the 8.7 keV line (at the energy of
the FeXXVI Lyγ line) in the spectrum of the Galactic Center
observed by the Suzaku X-ray mission.
Not easily explained by standard ionization and
recombination processes.
Proposed issue:
the origin of this excess is via decays of sterile neutrinos with
m ~ 17.4 keV and mixing angle sin2(2θ) =(4.1±2.2)×10−12
[Prokhorov & Silk 2010]
But:
- possible non-standard ionization and recombination processes
80
83. Pamela and ATIC
Charge-dependent solar Rapid climb above 10 GeV
modulation important indicates the presence of a
below 5-10 GeV primary source of cosmic
ray positrons!
Pamela
ATIC
Astrophysical expectation
(secondary production) 83
84. HESS and Fermi
Fermi and HESS do not confirm ATIC: Astrophysics can explain PAMELA:
→ consistent with bkgd. expectations - Pulsars
- SN remnants
- Diffusion effects
Fermi Collaboration (2009)
[Zhang, Cheng (2001); Hooper et al. (2008)
Yuksel et al. (2008); Profumo (2008)
Fermi LAT Collaboration (2009)]
84
85. Outline
Multi-epoch
The Dark Matter Timeline
The present
Multi-Scale
DM search at various astronomical scales
• Galactic center
• Galactic structures
• Galaxy Clusters
The Future
The DM search challenge
85
86. Neutralino DM: Hidden DM !?!
Experimental Frustration
• No direct evidence (DAMA vs. other underground experiments)
• No photonic signals (only upper limits from Multi-ν analysis)
• No particle signal (Pamela → ATIC: embarassing results)
What do we really know about dark matter?
Pause All solid evidence is gravitational
Also solid evidence against strong and EM interactions
The anomalies (DAMA, PAMELA, ATIC, …) are not easily explained
@ by canonical WIMPs → go beyond MSSM WIMP model
A reasonable 1st order guess:
Return Dark Matter has no SM gauge interactions, i.e., it is hidden
[Kobsarev, Okun, Pomeranchuk (1966); many others]
What one seemingly loses: [Feng et al. 2009]
Esc Connection to central problems of particle physics
Non-gravitational signals
86
The WIMP miracle
87. … some conclusions
• Astrophysical (e.m.) search is a crucial probe for the DM nature.
• Multi3-4 search in optimal astrophysical laboratories is the key
issue but is challenging.
• The temptation to explain every astrophysical anomaly as due to
DM is pushing DM search towards a fundamentalist approach
rather than to search for the its fundamental nature.
• The possible lack of DM evidence should be considered
positively as the necessity to explore in further details the basic
laws of the Universe
→ Gravity field modification on cosmological scales…
87
88. DM … or Modified Gravity !?!
Dark Matter
Could MOG explain also the dynamics
of the bullet cluster ?
J. Moffat says, "If the multi-billion dollar laboratory experiments now underway succeed
in directly detecting dark matter, then I will be happy to see Einstein and Newtonian
gravity retained. However, if dark matter is not detected and we have to conclude that
it does not exist, then Einstein and Newtonian gravity must be modified to fit the
extensive amount of astronomical and cosmological data, such as the bullet cluster,
that cannot otherwise be explained.
88