Found 7 talks width keyword cold dark matter
Twenty years ago, no one convincingly knew the age or the size of the
Universe to within a factor of two. Ten years ago, everyone agreed on
those same two numbers to within 10%. Today, we arguably have brought
the errors down by another factor of two. But that has led to anxiety
rather than euphoria, renewed interest rather than complacency. The
problem is that there are now two independent, competing methods
giving answers of comparable precision and accuracy:
one is a model-based method using the cosmic microwave background
(the CMB), the other is a geometric, parallax-based method using local
measures of distances and expansion velocities. To within about
two-sigma the methods agree. To within about two-sigma the methods
disagree. And basic physics (a fourth neutrino species, perhaps) hangs
in the balance.
I will discuss how this "tension" arose and how it will soon be
relieved. A tie-breaker has been identified and developed, and it is
now being worked on from the ground and from space.
I will review some theoretical ideas in Cosmology different to the standard "Big Bang": the Quasi-steady State model, Plasma Cosmology model, non-cosmological redshifts, alternatives to non-baryonic dark matter and/or dark energy, and others. Some open problems of Cosmology within the standard model will also be summarized.
In the first part of this talk I will present a historical review of the CMB observations, one of the most powerful cosmological probes. Following the first talk of this series, where Jose Alberto described the basic parameters that define the standard cosmological model, I will here summarize the constraints to these parameters that have been derived from these observations. I will also describe the current challenges in this field, in particular the detection of the inflation's B-mode signal through CMB polarization observations, as well as the experiments that have been developed worldwide to this aim, including IAC's QUIJOTE. In the second part, I will focus on the so-called ``missing baryon problem'', i.e. the fact that the half of the expected baryon content of the local universe remains yet undetected. I will describe the theoretical studies that provide hints on where these baryons could be located, and the observational efforts that have been undertaken in this regard.
This is the first talk of a series of four aimed to discuss about Cosmology. Here, I will review the basic concepts of the standard cosmological model, which will be further discussed in the following talks, as well as the observational evidence in support of the Lambda-CDM model. As the subject is very broad, I will focus the discussion on topics related with inflation, dark matter and dark energy. Moreover, I will mainly discuss large scale structure probes.
The distribution of matter in galaxies of different luminosities and Hubble types, as inferred from observations, plays an important role in cosmology, extragalactic astrophysics, astroparticle physics, as well as in a number of issues in high-energy astrophysics, galactic astronomy, star formation and evolution and general relativity. Not withstanding the general successes of the ΛCDM model in explaining the structure and evolution of the universe, there is a growing conviction that the structural properties of the dark and luminous components in galaxies hold important clues about the nature of dark matter and about the processes that are responsible for galaxy formation. This talk is part of an international initiative known as "Dark Matter Awareness Week".The overall purpose of this event is to increase the awareness of the phenomenology of the mass discrepancy phenomenon in galaxies amongst the many scientists currently working with a theoretical, observational, experimental and simulation approach on issues involving dark matter or its alternatives. The content of the talk will be at the level of a journal club talk with an important dose of review.
AbstractThe standard model of cosmology -- the ``Lambda cold dark matter'' model -- is based on the idea that the dark matter is a collisionless elementary particle, probably a supersymmetric particle. This model (which mostly dates back to an early workshop in Santa Barbara in the 1980s) has been famously verified by observations of the cosmic microwave background radiation and the large-scale distribution of galaxies. However, the model has yet to be tested conclusively on the small scales appropriate to most astronomical objects, such as galaxies and clusters. I will review our current understanding of the distribution of dark matter on small scales which derives largely from large cosmological N-body simulations and I will discuss prospects for detecting dark matter, either through its gravitational effect on galaxies and clusters or, more directly, through gamma-ray annihilation radiation.
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- Adaptive Optics the other way round: pre-correcting the uplinkNoelia Martínez ReyWednesday July 24, 2019 - 15:30 (GTC room)