Simulation von Elektronendynamik in autoionisierenden Heliumniveaus unter dem Einfluss ultrakurzer Laserpulse

In this work, a model for simulating electron dynamics in strong femtosecond-laser fields was developped. Autoionizing states in helium were examined, where interference with the continuum plays a vital role. Quantum interference effects ocurring after few Rabi cycles in strong laser fields also play an important role in understanding the light-matter-interaction. Fano-resonances and the Stark-shift in the laser field were observed and compared to measurements

Joint halo-mass function for modified gravity and massive neutrinos - I. Simulations and cosmological forecasts

We present a halo-mass function accurate over the full relevant Hu-Sawicki f(R) parameter space based on spherical collapse calculations and calibrated to a suite of modified gravity N-body simulations that include massive neutrinos. We investigate the ability of current and forthcoming galaxy cluster observations to detect deviations from general relativity while constraining the total neutrino mass and including systematic uncertainties. Our results indicate that the degeneracy between massive neutrino and modify gravity effects is a limiting factor for the current searches for new gravitational physics with clusters of galaxies, but future surveys will be able to break the degeneracy

CODEX clusters : Survey, catalog, and cosmology of the X-ray luminosity function

Context. Large area catalogs of galaxy clusters constructed from ROSAT All-Sky Survey provide the basis for our knowledge of the population of clusters thanks to long-term multiwavelength efforts to follow up observations of these clusters.Aims. The advent of large area photometric surveys superseding previous, in-depth all-sky data allows us to revisit the construction of X-ray cluster catalogs, extending the study to lower cluster masses and higher redshifts and providing modeling of the selection function.Methods. We performed a wavelet detection of X-ray sources and made extensive simulations of the detection of clusters in the RASS data. We assigned an optical richness to each of the 24 788 detected X-ray sources in the 10 382 square degrees of the Baryon Oscillation Spectroscopic Survey area using red sequence cluster finder redMaPPer version 5.2 run on Sloan Digital Sky Survey photometry. We named this survey COnstrain Dark Energy with X-ray (CODEX) clusters.Results. We show that there is no obvious separation of sources on galaxy clusters and active galactic nuclei (AGN) based on the distribution of systems on their richness. This is a combination of an increasing number of galaxy groups and their selection via the identification of X-ray sources either by chance or by groups hosting an AGN. To clean the sample, we use a cut on the optical richness at the level corresponding to the 10% completeness of the survey and include it in the modeling of the cluster selection function. We present the X-ray catalog extending to a redshift of 0.6.Conclusions. The CODEX suvey is the first large area X-ray selected catalog of northern clusters reaching fluxes of 10(-13) ergs s(-1) cm(-2). We provide modeling of the sample selection and discuss the redshift evolution of the high end of the X-ray luminosity function (XLF). Our results on z<0.3 XLF agree with previous studies, while we provide new constraints on the 0.3<z<0.6 XLF. We find a lack of strong redshift evolution of the XLF, provide exact modeling of the effect of low number statistics and AGN contamination, and present the resulting constraints on the flat CDM.Peer reviewe

Reconstruction and control of a time-dependent two-electron wave packet

The concerted motion of two or more bound electrons governs atomic1 and molecular2,3 non-equilibrium processes including chemical reactions, and hence there is much interest in developing a detailed understanding of such electron dynamics in the quantum regime. However, there is no exact solution for the quantumthree-body problem, and as a result even the minimal system of two active electrons and a nucleus is analytically intractable4. This makes experimental measurements of the dynamics of two bound and correlated electrons, as found in the helium atom, an attractive prospect.However, although the motion of single active electrons and holes has been observed with attosecond time resolution5-7, comparable experiments on two-electron motion have so far remained out of reach. Here we showthat a correlated two-electron wave packet can be reconstructed froma 1.2-femtosecondquantumbeatamong low-lying doubly excited states in helium.The beat appears in attosecond transient-absorption spectra5,7-9 measured with unprecedentedly high spectral resolution and in the presence of an intensity-tunable visible laser field.Wetune the coupling10-12 between the two low-lying quantum states by adjusting the visible laser intensity, and use the Fano resonance as a phase-sensitive quantum interferometer13 to achieve coherent control of the two correlated electrons. Given the excellent agreement with large-scalequantum-mechanical calculations for thehelium atom, we anticipate thatmultidimensional spectroscopy experiments of the type we report here will provide benchmark data for testing fundamental few-body quantumdynamics theory in more complex systems. Theymight also provide a route to the site-specificmeasurement and control of metastable electronic transition states that are at the heart of fundamental chemical reactionsWe thank E. Lindroth for calculating the dipole moment (2p2|r|sp2,3+), and also A. Voitkiv, Z.-H. Loh, and R. Moshammer for helpful discussions. We acknowledge financial support by the Max-Planck Research Group Program of the Max-Planck Gesellschaft (MPG) and the European COST Action CM1204 XLIC. L. A. and F. M. acknowledge computer time from the CCC-UAM and Mare Nostrum supercomputer centers and financial support by the European Research Council under the ERC Advanced Grant no. 290853 XCHEM, the Ministerio de Economía y Competitividad projects FIS2010-15127, FIS2013-42002-R and ERA-Chemistry PIM2010EEC-00751, and the European grant MC-ITN CORIN

Exploring cosmic origins with CORE: Gravitational lensing of the CMB

Lensing of the CMB is now a well-developed probe of large-scale clustering over a broad range of redshifts. By exploiting the non-Gaussian imprints of lensing in the polarization of the CMB, the CORE mission can produce a clean map of the lensing deflections over nearly the full-sky. The number of high-S/N modes in this map will exceed current CMB lensing maps by a factor of 40, and the measurement will be sample-variance limited on all scales where linear theory is valid. Here, we summarise this mission product and discuss the science that it will enable. For example, the summed mass of neutrinos will be determined to an accuracy of 17 meV combining CORE lensing and CMB two-point information with contemporaneous BAO measurements, three times smaller than the minimum total mass allowed by neutrino oscillations. In the search for B-mode polarization from primordial gravitational waves with CORE, lens-induced B-modes will dominate over instrument noise, limiting constraints on the gravitational wave power spectrum amplitude. With lensing reconstructed by CORE, one can "delens" the observed polarization internally, reducing the lensing B-mode power by 60%. This improves to 70% by combining lensing and CIB measurements from CORE, reducing the error on the gravitational wave amplitude by 2.5 compared to no delensing (in the null hypothesis). Lensing measurements from CORE will allow calibration of the halo masses of the 40000 galaxy clusters that it will find, with constraints dominated by the clean polarization-based estimators. CORE can accurately remove Galactic emission from CMB maps with its 19 frequency channels. We present initial findings that show that residual Galactic foreground contamination will not be a significant source of bias for lensing power spectrum measurements with CORE. [abridged

Exploring cosmic origins with CORE : Effects of observer peculiar motion

We discuss the effects on the cosmic microwave background (CMB), cosmic infrared background (CIB), and thermal Sunyaev-Zeldovich effect due to the peculiar motion of an observer with respect to the CMB rest frame, which induces boosting effects. After a brief review of the current observational and theoretical status, we investigate the scientific perspectives opened by future CMB space missions, focussing on the Cosmic Origins Explorer (CORE) proposal. The improvements in sensitivity offered by a mission like CORE, together with its high resolution over a wide frequency range, will provide a more accurate estimate of the CMB dipole. The extension of boosting effects to polarization and cross-correlations will enable a more robust determination of purely velocity-driven effects that are not degenerate with the intrinsic CMB dipole, allowing us to achieve an overall signal-to-noise ratio of 13; this improves on the Planck detection and essentially equals that of an ideal cosmic variance-limited experiment up to a multipole l similar or equal to 2000. Precise inter-frequency calibration will offer the opportunity to constrain or even detect CMB spectral distortions, particularly from the cosmological reionization epoch, because of the frequency dependence of the dipole spectrum, without resorting to precise absolute calibration. The expected improvement with respect to COBE-FIRAS in the recovery of distortion parameters (which could in principle be a factor of several hundred for an ideal experiment with the CORE configuration) ranges from a factor of several up to about 50, depending on the quality of foreground removal and relative calibration. Even in the case of similar or equal to 1% accuracy in both foreground removal and relative calibration at an angular scale of 1 degrees, we find that dipole analyses for a mission like CORE will be able to improve the recovery of the CIB spectrum amplitude by a factor similar or equal to 17 in comparison with current results based on COBE-FIRAS. In addition to the scientific potential of a mission like CORE for these analyses, synergies with other planned and ongoing projects are also discussed.Peer reviewe

Exploring Cosmic Origins with CORE: Cluster Science

We examine the cosmological constraints that can be achieved with a galaxycluster survey with the future CORE space mission. Using realistic simulationsof the millimeter sky, produced with the latest version of the Planck SkyModel, we characterize the CORE cluster catalogues as a function of the mainmission performance parameters. We pay particular attention to telescope size,key to improved angular resolution, and discuss the comparison and thecomplementarity of CORE with ambitious future ground-based CMB experiments thatcould be deployed in the next decade. A possible CORE mission concept with a150 cm diameter primary mirror can detect of the order of 50,000 clustersthrough the thermal Sunyaev-Zeldovich effect (SZE). The total yield increases(decreases) by 25% when increasing (decreasing) the mirror diameter by 30 cm.The 150 cm telescope configuration will detect the most massive clusters($>10^{14}\, M_\odot$) at redshift $z>1.5$ over the whole sky, although theexact number above this redshift is tied to the uncertain evolution of thecluster SZE flux-mass relation; assuming self-similar evolution, CORE willdetect $\sim 500$ clusters at redshift $z>1.5$. This changes to 800 (200) whenincreasing (decreasing) the mirror size by 30 cm. CORE will be able to measureindividual cluster halo masses through lensing of the cosmic microwavebackground anisotropies with a 1-$\sigma$ sensitivity of $4\times10^{14}M_\odot$, for a 120 cm aperture telescope, and $10^{14} M_\odot$ for a 180 cmone. [abridged

Exploring Cosmic Origins with CORE: The Instrument

We describe a space-borne, multi-band, multi-beam polarimeter aiming at aprecise and accurate measurement of the polarization of the Cosmic MicrowaveBackground. The instrument is optimized to be compatible with the strict budgetrequirements of a medium-size space mission within the Cosmic Vision Programmeof the European Space Agency. The instrument has no moving parts, and usesarrays of diffraction-limited Kinetic Inductance Detectors to cover thefrequency range from 60 GHz to 600 GHz in 19 wide bands, in the focal plane ofa 1.2 m aperture telescope cooled at 40 K, allowing for an accurate extractionof the CMB signal from polarized foreground emission. The projected CMBpolarization survey sensitivity of this instrument, after foregrounds removal,is 1.7 {\mu}K$\cdot$arcmin. The design is robust enough to allow, if needed, adownscoped version of the instrument covering the 100 GHz to 600 GHz range witha 0.8 m aperture telescope cooled at 85 K, with a projected CMB polarizationsurvey sensitivity of 3.2 {\mu}K$\cdot$arcmin

Exploring cosmic origins with CORE : Inflation

We forecast the scientific capabilities to improve our understanding of cosmic inflation of CORE, a proposed CMB space satellite submitted in response to the ESA fifth call for a medium-size mission opportunity. The CORE satellite will map the CMB anisotropies in temperature and polarization in 19 frequency channels spanning the range 60-600 GHz. CORE will have an aggregate noise sensitivity of 1.7 mu K.arcmin and an angular resolution of 5' at 200 GHz. We explore the impact of telescope size and noise sensitivity on the inflation science return by making forecasts for several instrumental configurations. This study assumes that the lower and higher frequency channels suffice to remove foreground contaminations and complements other related studies of component separation and systematic effects, which will be reported in other papers of the series "Exploring Cosmic Origins with CORE." We forecast the capability to determine key inflationary parameters, to lower the detection limit for the tensor-to-scalar ratio down to the 10(-3) level, to chart the landscape of single field slow-roll inflationary models, to constrain the epoch of reheating, thus connecting inflation to the standard radiation-matter dominated Big Bang era, to reconstruct the primordial power spectrum, to constrain the contribution from isocurvature perturbations to the 10(-3) level, to improve constraints on the cosmic string tension to a level below the presumptive GUT scale, and to improve the current measurements of primordial non-Gaussianities down to the f(NL)(local) <1 level. For all the models explored, CORE alone will improve significantly on the present constraints on the physics of inflation. Its capabilities will be further enhanced by combining with complementary future cosmological observations.Peer reviewe

Exploring Cosmic Origins with CORE: Survey requirements and mission design

Future observations of cosmic microwave background (CMB) polarisation havethe potential to answer some of the most fundamental questions of modernphysics and cosmology. In this paper, we list the requirements for a future CMBpolarisation survey addressing these scientific objectives, and discuss thedesign drivers of the CORE space mission proposed to ESA in answer to the "M5"call for a medium-sized mission. The rationale and options, and themethodologies used to assess the mission's performance, are of interest toother future CMB mission design studies. CORE is designed as a near-ultimateCMB polarisation mission which, for optimal complementarity with ground-basedobservations, will perform the observations that are known to be essential toCMB polarisation scienceand cannot be obtained by any other means than adedicated space mission