Found 24 talks width keyword CMB
In cosmology, it is customary to convert observed redshifts into distances in order to study the large scale distribution of matter probes like galaxies and quasars, and to obtain cosmological constraints thereof. In this talk, I describe a new approach which bypasses such conversion and studies the "field of redshifts" as a new cosmological observable, dubbed thereafter as angular redshift fluctuations (ARF). By comparing linear theory predictions to the output of N-body cosmological simulations, I will show how the ARF are actually sensitive to both the underlying density and radial peculiar velocity fields in the universe, and how one can obtain cosmological and astrophysical constraints from them. And since "the prove of the pudding is in the eating", I will demonstrate how ARF provide, under a very simple setup, competitive constraints on the nature of peculiar velocities and gravity from BOSS DR13 data. Furthermore, I will also show that by combining ARF with maps of the cosmic microwave background (CMB), we can unveil the signature of the missing (and moving) baryons, doubling the amount of detected baryons in disparate cosmic epochs ranging from z=0 up to z=5, and providing today's most precise description of the spatial distribution of baryons in the universe.
In this talk, we shall review the impact of the neutrino properties on the different cosmological observables. We shall also present the latest cosmological constraints on the neutrino masses and on the effective number of relativistic species. Special attention would be devoted to the role of neutrinos in solving the present cosmological tensions.
Dr Roger Hoyland has been working at the IAC for the last 21 years on the Cosmic Microwave Background Experiments. He started out as a research assistant at Jodrell Bank, University of Manchester, near his home town. His expertise lies in sensitive microwave radiometer design. He has worked on various projects such as the Tenerife Experiments, The Planck Surveyor Mission and The QUIJOTE project.
This talk is for the general public (even if mostly scientific) and aims to explain some of the misunderstandings and myths about microwave devices that we use in our everyday life. There are many YouTube videos about the effects of microwaves but which do you believe? Does your mobile phone really cause interference in an airplane? Can you really destroy your credit card by carrying it next to your mobile? Does the EMP bomb really exist? All this and more…………….
With the help of several live experiments and some audience participation (be prepared!) you will find out the science behind the myths around mobiles, microwave ovens and other microwave devices.
PS: Please bring along your mobile phone if you have one.
The ``dark flow'' dipole is a statistically significant dipole found at the position of galaxy clusters in filtered maps of Cosmic Microwave Background (CMB) temperature anisotropies. The dipole measured in WMAP 3, 5 and 7 yr data releases was roughly aligned with the all-sky CMB dipole and correlated with cluster X-ray luminosity. We analyzed the final WMAP 9 yr and the first Planck data releases using a catalog of 980 clusters outside the Kp0 mask to test our earlier findings. The dipoles measured on these new data sets are fully compatible with our earlier estimates, being similar in amplitude and direction to our previous results and in disagreement with the results of an earlier study by the Planck Collaboration. Further, in Planck data dipoles are independent of frequency, ruling out the Thermal Sunyaev-Zeldovich as the source of the effect. The signal is dominated by the most massive clusters, with a statistical significance better than 99%, slightly larger than in WMAP. Since both data sets differ in foreground contributions, instrumental noise and other systematics, the agreement between WMAP and Planck dipoles argues against them being due to systematic effects in either of the experiments.
We have learned a great deal about the universe from measurements ofthe cosmic microwave background (CMB). Most of what we have learned so far has been based on the temperature anisotropy combined with measurements of the polarization at angular scales of roughly 10 degrees. We are entering a new era in which the polarization of the CMB will be measured to high accuracy especially at degree angular scales and smaller. With the polarization we can, for example, measure or limit the presence of gravitational radiation from the early universe and determine the sum of the neutrino masses. The polarization will also give us a new way to determine the cosmological parameters. We review recent results on the CMB polarization with anemphasis on those from the Atacama Cosmology Telescope (ACT) project.
On March 17 the team responsible for the BICEP2 experiment, a CMB telescope located in the South Pole, announced the discovery of the primordial B-mode signal in the CMB polarization. This discovery inmediatly had a well-deserved impact in the media world-wide. In fact, it is the first observational confirmation of a prediction from the inflationary model, which was proposed at the beginning of the 80s as a solution for some inconsistencies of the Big Bang model. In this talk I will put this discovery in the context of CMB research, with a historical perspective. I will emphasize the importance of this discovery for Cosmology, and for Fundamental Physics, and will finally comment the prospects for the future, in particular the role of experiments like Quijote that have to confirm this signal.
Next generation of CMB experiments will require a large number of detectors (few tens of thousands) in order to tackle the challenging detection of primordial polarization B modes. Furthermore, high resolution experiments are needed for a detailed study of high redshift objects including clusters of galaxies, proto-clusters and dusty galaxies. Within this context Kinetic Inductance Detectors (KIDs) are a serious alternative to bolometers at millimetre wavelengths. Indeed, KIDs are naturally multiplexed and compact allowing us to construct arrays of thousands of detectors. Furthermore, KIDs present short time constants (below 1 ms) and have been demonstrated to be background limited on ground based observations. The NIKA camera, made of two matrices (200 KIDs each) operated at 140 and 240 GHz, has been installed successfully at the IRAM 30 m telescope in Pico Veleta, Granada. NIKA has provided the first ever scientific quality astrophysical observations with KIDs. In particular RXJ1347.5-1145, a massive intermediate redshift galaxy cluster at z = 0.4516 undergoing a merging event, has been successfully mapped at 12 arcsec resolution by NIKA. NIKA is a general purpose camera and it can be also used for other astrophysical objectives including for example observations of high redshift galaxies and proto-clusters, and detailed intensity and polarisation mapping of star-forming regions in the Galaxy. NIKA is a prototype of the NIKA2 camera that should be installed in 2015 at the IRAM 30 m telescope. NIKA2 should have 2 frequency bands at 150 and 250 GHz with about 5000 detectors in total and polarisation capabilities. NIKA2 will be well-suited for in-depth studies of the Intra Cluster Medium in intermediate to high redshift clusters and the follow-up of clusters and proto-clusters newly discovered by the Planck satellite. Finally, we discuss the possibility of including KIDs in the next generation of CMB satellites as for example PRISM.
About half the baryons in the local Universe could be in the form of a Warm Hot Intergalactic Medium (WHIM). If a large fraction of the gas is ionized, it could produce significant temperature anisotropies in the Cosmic Microwave Background (CMB), generated by the thermal and also the kinematic Sunyaev-Zeldovich effect. We have developed a theoretical framework to describe the mildly non-linear regime of the WHIM that allows us to compute its contribution to CMB anisotropies. We discuss prospective ways of detecting the WHIM contribution using our formalism and discuss our results on PLANCK data and the constraints we set on the WHIM parameters.
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.
1) Overview on Planck and QUIJOTE. R. Rebolo 15 min. 2) The Galaxy as seen by Planck. R. Génova-Santos 15 min. 3) Planck Cosmological Results. J. A. Rubiño-Martín 20 min (times approximate). We will give an overview of two Cosmic Microwave Experiments with a significant involvement of the IAC. The ESA mission Planck has recently released its first set of Cosmological Results. QUIJOTE is a CMB polarization experiment which has recently started scientific operation at Teide Observatory. We will show the first results and the potential of QUIJOTE and we will provide an overview of the Planck mission and its impact on Galactic science and on Cosmology.
« Newer 1 | 2 | 3 Older » Last >>
- TODAY: MARK I: an astronomer's lifetime experimentProf. Teodoro Roca CortésTuesday November 30, 2021 - 10:30 GMT (Museo de la Ciencia y el Cosmos)
- The multiple routes of galaxy transformation across the cosmic epochsProf. Roberto MaiolinoThursday December 2, 2021 - 10:30 GMT (Aula)