List of all the talks in the archive, sorted by date.
Star formation and supermassive black hole growth in galaxies appear to be self limiting. The mechanisms for self regulation are known as /feedback/. Cosmic rays, the relativistic particle component in interstellar and intergalactic plasma, are among the agents of feedback. Because cosmic rays are virtually collisionless in the plasma environments of interest, their interaction with the ambient medium is primarily mediated by large scale magnetic fields and kinetic scale plasma waves. Because kinetic scales are much smaller than global scales, this interaction is most conveniently described by fluid models. In this paper I discuss the kinetic theory and the classical theory of cosmic ray hydrodynamics (CCRH) which follows from assuming cosmic rays interact only with self excited waves. I generalize CCRH to generalized cosmic ray hydrodynamics (GCRH), which accommodates interactions with extrinsic turbulence, present examples of cosmic ray feedback in galaxies and galaxy clusters, and assess where progress is needed.
The improvement on the Imaging Air Cherenkov Technique led to the discovery of a new class of compact binaries: the gamma-ray binaries. This small class consist of only five members, all of them composed by a massive star and a compact object. The nature of the compact object is unknown for all of them but PSR B1259-63, which contains a pulsar. It is crucial to study and monitor these systems not only to understand their behavior, the scenario accounting for the gamma-ray emission and their nature but also to comprehend why we have not detected more sources of this exclusive family. In this presentation, I will review the state-of-the-art of this field and I will present the observations performed with the MAGIC telescopes in order to unveil the nature of gamma-ray binaries.
Based on radial profiles, disk can be divided into three categories:Type I, classical single exponential (10%); Type II, down-bending joint exponential (60%); Type III, up-bending joint exponential (30%). Milky Way is the benchmark for the research of the disk Galaxy formation and evolution! And the outer disks of galaxies present a unique laboratory for studying the process of disk formation and it can provide us with a direct view of disk assembly in progress. I will introduce my recent work about the milky way outer disk. And some highlights about our group works with LAMOST data will also be mentioned.
China joined SONG in 2009, by contributing a full SONG node. The site is located on the north-eastern part of Qinghai-Tibet
plateau. In order to realize the full capability of the SONG network, and more importantly for Chinese astronomical community
to gain experience of running oversea observing facilities, we proposed to our collaborators to add a wide-field photometry
system on each SONG node based on the same site plan. The sub-net is named 50cm Binocular Network (50BiN), which provides
time-series photometry of simultaneous two-bands (any two of UBVRI-ugriz), and ideally full duty cycle in networked mode
(if the full SONG would be built). The proto-type 50BiN node has been in operation on Chinese site (Delingha) for 3 years.
An overview of the grand science plan, configuration of the network and instruments, as well as some science cases will be
presented in this talk. A brief introduction to the status of ground-based Chinese observing facilities will also be covered.
En 1915 Albert Einstein publica su teoría general de la relatividad y con ella predice la existencia de las llamadas ondas gravitacionales. Cien años después, dos importantísimos hitos científicos relacionados con esta predicción tienen lugar. Primero, el anuncio de la detección directa de ondas gravitacionales confirma la teoría de Einstein, marcando el comienzo de la Astronomía Gravitacional. El segundo hecho clave ha sido el éxito de la misión espacial LISA Pathfinder, satélite que ha probado la tecnología necesaria para los futuros observatorios de ondas gravitacionales en el espacio. Los continuos avances científicos y tecnológicos de las últimas décadas han permitido abrir esta nueva ventana a un universo lleno de revolucionarios descubrimientos que esperan ya ser desvelados.
Phylogenetics, a concept being widely-used in biology, is the reconstruction of evolutionary history by building trees that represent branching patterns and sequences. These trees represent shared history, and it is our contention that this approach can be employed in the analysis of Galactic history, where the shared environment in which stars form provide the basis for tree-building as a methodological tool. In this talk I will discuss how evolutionary trees can be built with twin stars and how this gains new insights into the structure and evolution of the Milky Way.
The standard model of cosmology has been quite successful accounting for a broad range of data - at least until the past few years. But as the quality of cosmological measurements has continued to improve, tension has grown between observations and the predictions of LCDM. In this talk, we will address several "problem" areas, and then focus on the most recent: the emergence of a rather strong non-inflationary signature in the angular correlation function of the microwave background. Inflation is critical to the internal self-consistency of the standard model. Yet after 4 decades, we still lack convincing evidence that it ever happened.
The S-class MESSIER satellite has been designed to explore the extremely low surface brightness universe at UV and optical wavelengths. The two driving science cases target the mildly- and highly non-linear regimes of structure formation to test two key predictions of the LCDM scenario: (1) the detection of the putative large number of galaxy satellites, and (2) the identification of the filaments of the cosmic web. The science requirements imply challenging instrumentation issues which have only recently been solved. The satellite will drift scan the entire sky in 6 bands covering the 200-1000 nm wavelength range to reach the unprecedented surface brightness levels of 34 mag/arcsec^2 in the optical and 37 mag/arcsec^2 in the UV. As usual when uncovering new volumes in parameter space, many important secondary science cases will also result as free by-products and will be discussed in some detail: the actual luminosity function of galaxies, the contribution and role of intracluster light, the fluctuations of the cosmological background radiation at UV and optical wavelengths, the warm molecular hydrogen content of galaxies at z=0.25, time-domain studies of supernovae and tidal disruption events, the chemical enrichment of the interstellar medium through mass loss of red giant stars and the accurate measure of the BAO scale at z=0.7 with over 30 million galaxies detected in Lyman-alpha at this redshift. It will provide the first space-based reference UV-optical photometric catalogue of the entire sky, and synergies with GAIA, EUCLID and WFIRST will also be discussed.
¿Cuáles son los primeros pasos que tenemos que dar en el diseño de una cámara para el espacio?
- TODAY: The Pristine survey: An efficient search for extremely metal-poor starsDr. Kris YouakimTuesday January 23, 2018 - 12:30
- On the evolution of rotation and magnetism from solar-like stars to red giants using Kepler dataDr. Savita MathurThursday February 1, 2018 - 10:30