A brief Intro
 
I work in Cosmology, that is, the branch of Astrophysics that studies our Universe as a whole: its beginning, its growth and its evolution until it reaches its present stage. In particular, my research has focused on the Cosmic Microwave Background (CMB) radiation.
 
In the standard model of our Universe, matter and radiation were coupled at the very early times: by then the Universe was so small and dense that light could not freely propagate due to constant encounters with electrons. This not only kept both species in thermal equilibrium, but also attached the evolution of small inhomogeneities in the matter distribution to equivalent inhomogeneities in the radiation field. These small clumps in the matter and energy distribution are regarded as the seeds of current structures like galaxies and clusters of galaxies. 
 
When the Universe was about 380,000 years old, most electrons recombined with protons to form hydrogen (the most abundant element in our Universe), so light did not find any more electrons in its way and could propagate without being scattered. The CMB is that "light", that, after crossing the whole visible Universe, is reaching us carrying precious physical information about the energy inhomogeneities of the Universe during its youngest ages. The statistical properties of these inhomogeneities (that today can be measured as tiny fluctuations in the CMB radiation intensity and polarization) provide a unique insight of how the Universe was during the epoch of recombination, and permit testing existing theories of the Universe origin and evolution.
 
Further, since the CMB radiation has crossed the evolving Universe, it has had the chance to interact with changing and growing structures such as clouds of metals produced by the first stars, clusters of galaxies, varying in time gravitational potentials, etc. All these processes have left their imprint on the CMB radiation (in the form of secondary anisotropies), and our goal is to identify and interpret them.
 
Galaxies are supossed to arise through gravitational collapse in those formerly slightly overdense regions that interacted with the CMB radiation before the epoch of recombination. Relatively simple physics describing that interation is able to predict the existence of a preferred distance between matter particles that arises as a consequence of the cross-talk to the CMB radiation field at early cosmological times. If the angle subtended by that distance can be measured at different cosmological epochs (i.e., at different distances from the observer), then this would provide a unique insight on how  the universe has been expanding during those epochs. In other words, this would shed light on the nature of Dark Energy, the misterious energetic component that seems to be accelerating the universal expansion.
 
This is the major driver for the J-PAS survey to be conducted at the Observatorio Astrofísico de Javalambre (OAJ), situated in Teruel (Spain). However, this survey should enable addressing a huge amount of other, first line, scientific problems, ranging from asteroids, planet search, stellar evolution, galactic science, galaxy evolution, QSOs and Cosmology.
 
 
 
My research lines
 
I have spent most of my research efforts in the study of the CMB anisotropies, although since I am at CEFCA  I am slowly gearing into the analysis of Large Scale Structure and its cosmological implications. I would divide my research interests in three different points:
 
     1.- On the intrinsic CMB temperature anisotropies:
 
    •    Hydrogen recombination and the generation of the intrinsic CMB temperature angular power spectrum.
    •    Cross-correlation of weak frequency dependent signals with the CMB field.
    •    Primordial Magnetic Fields (PMF) and their effect on CMB intensity and polarization.
    •    Excursion set statistics in gaussian fields (such as the CMB) and its application in fast Power Spectrum estimation.
  
      2.- On the secondary CMB temperature anisotropies:
 
    •    Interaction of CMB radiation with the first metals and molecules generated during the Dark Ages and subsequent reionization.
    •    Temperature anisotropies introduced in the CMB by hot electron plasma via the thermal Sunyaev-Zel'dovich effect (tSZ).
    •    Temperature anisotropies introduced in the CMB by peculiar velocities of electron clouds via the kinematic Sunyaev-Zel'dovich effect (kSZ). Study of bulk flows and their link to Dark Energy.
    •    Imprint of the merging galaxy cluster population on the CMB field via the Rees-Sciama effect.
    •    Interaction of CMB photons with evolving gravitational potentials via the Integrated Sachs-Wolfe effect (ISW). Cross talk of the ISW with other secondary effects.
 
      3.- On the analysis of the Large Scale Structure in the Universe
 
    •    Estimation of 2D and 3D power spectrum of the galaxy distribution. Cosmological implications
 
 
Major Projects
 
I am currently involved in several major projects.
 
    1.-The J-PAS survey will be conducted in the OAJ, with the purpose of setting constraints on Dark Energy. For that, J-PAS will sweep  8,500 square degrees of the equatorial northern sky up to z~1.1 for Luminous Red Galaxies and z~3 for QSOs; and charcterize the matter distribution within that cosmological volume. I am leading CEFCA’s Cosmology group in this collaboration.
 
     2.- Planck: This is a major european effort to map the intensity and polarization CMB anisotropies. It consists of two instruments: the Low Frequency Instrument (LFI, 30 - 70 GHz), and the High Frequency Instrument (HFI, 100 - 850 GHz). It was launched on May 18th 2009. I am co-leading the ISW project within Planck, leading the work package on bulk flows and diffuse kSZ effect.  I am also involved in many other projects related to diffuse baryons, reionization and primordial magnetic fields.
 
    3.- ALHAMBRA: This is a deep 2.5 square degree survey conducted in the Calar Alto Observatory (Almería, Spain), and its multi narrow filter camera can be seen as a precursor of that of J-PAS.
 
    4.- BOSS: This Sloan survey is measuring cosmological structure up to z~0.7-0.8 for the Luminous Red Galaxies (LRGs) and still deeper for sources like QSOs. Photometric redshifts obtained from 5 bands are trained with a vast spectroscopic sample.
 
    5.-The Atacama Cosmology Telescope is a collaboration led by Princeton University in the U.S. The goal is to measure with unprecedented sensitivity the small scale range of the CMB temperature fluctuations.
 
 
 
 
 
 
Research Interests
© Carlos Hernández Monteagudo, 2014