11 research outputs found
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: Mitigation of systematic effects
We present an analysis of the main systematic effects that could impact the measurement of CMB polarization with the proposed CORE space mission. We employ timeline-to-map simulations to verify that the CORE instrumental set-up and scanning strategy allow us to measure sky polarization to a level of accuracy adequate to the mission science goals. We also show how the CORE observations can be processed to mitigate the level of contamination by potentially worrying systematics, including intensity-to-polarization leakage due to bandpass mismatch, asymmetric main beams, pointing errors and correlated noise. We use analysis techniques that are well validated on data from current missions such as Planck to demonstrate how the residual contamination of the measurements by these effects can be brought to a level low enough not to hamper the scientific capability of the mission, nor significantly increase the overall error budget. We also present a prototype of the CORE photometric calibration pipeline, based on that used for Planck, and discuss its robustness to systematics, showing how CORE can achieve its calibration requirements. While a fine-grained assessment of the impact of systematics requires a level of knowledge of the system that can only be achieved in a future study phase, the analysis presented here strongly suggests that the main areas of concern for the CORE mission can be addressed using existing knowledge, techniques and algorithms
Filamentary structures of the cosmic web and the nonlinear Schrödinger type equation
We show that the filamentary type structures of the cosmic web can be modeled as solitonic waves by solving the reaction diffusion system which is the hydrodynamical analogous of the nonlinear Schrödinger type equation. We find the analytical solution of this system by applying the Hirota direct method which produces the dissipative soliton solutions to formulate the dynamical evolution of the nonlinear structure formation
PRISM (Polarized Radiation Imaging and Spectroscopy Mission): an extended white paper
Contains fulltext :
126057.pdf (preprint version ) (Open Access
Exploring Cosmic Origins with CORE: B-mode Component Separation
We demonstrate that, for the baseline design of the CORE satellite mission,
the polarized foregrounds can be controlled at the level required to allow the
detection of the primordial cosmic microwave background (CMB) -mode
polarization with the desired accuracy at both reionization and recombination
scales, for tensor-to-scalar ratio values of . We
consider detailed sky simulations based on state-of-the-art CMB observations
that consist of CMB polarization with and tensor-to-scalar values
ranging from to , Galactic synchrotron, and thermal dust
polarization with variable spectral indices over the sky, polarized anomalous
microwave emission, polarized infrared and radio sources, and gravitational
lensing effects. Using both parametric and blind approaches, we perform full
component separation and likelihood analysis of the simulations, allowing us to
quantify both uncertainties and biases on the reconstructed primordial
-modes. Under the assumption of perfect control of lensing effects, CORE
would measure an unbiased estimate of
after foreground cleaning. In the presence of both gravitational lensing
effects and astrophysical foregrounds, the significance of the detection is
lowered, with CORE achieving a -measurement of
after foreground cleaning and % delensing. For lower tensor-to-scalar
ratios () the overall uncertainty on is dominated by foreground
residuals, not by the 40% residual of lensing cosmic variance. Moreover, the
residual contribution of unprocessed polarized point-sources can be the
dominant foreground contamination to primordial B-modes at this level, even
on relatively large angular scales, . Finally, we report two
sources of potential bias for the detection of the primordial
-modes.[abridged]Comment: 87 pages, 32 figures, 4 tables, expanded abstract. Updated to match
version accepted by JCA
Exploring cosmic origins with CORE: Mitigation of systematic effects
We present an analysis of the main systematic effects that could impact the measurement of CMB polarization with the proposed CORE space mission. We employ timeline-to-map simulations to verify that the CORE instrumental set-up and scanning strategy allow us to measure sky polarization to a level of accuracy adequate to the mission science goals. We also show how the CORE observations can be processed to mitigate the level of contamination by potentially worrying systematics, including intensity-to-polarization leakage due to bandpass mismatch, asymmetric main beams, pointing errors and correlated noise. We use analysis techniques that are well validated on data from current missions such as Planck to demonstrate how the residual contamination of the measurements by these effects can be brought to a level low enough not to hamper the scientific capability of the mission, nor significantly increase the overall error budget. We also present a prototype of the CORE photometric calibration pipeline, based on that used for Planck, and discuss its robustness to systematics, showing how CORE can achieve its calibration requirements. While a fine-grained assessment of the impact of systematics requires a level of knowledge of the system that can only be achieved in a future study phase, the analysis presented here strongly suggests that the main areas of concern for the CORE mission can be addressed using existing knowledge, techniques and algorithms
Exploring Cosmic Origins with CORE: The Instrument
We describe a space-borne, multi-band, multi-beam polarimeter aiming at a
precise and accurate measurement of the polarization of the Cosmic Microwave
Background. The instrument is optimized to be compatible with the strict budget
requirements of a medium-size space mission within the Cosmic Vision Programme
of the European Space Agency. The instrument has no moving parts, and uses
arrays of diffraction-limited Kinetic Inductance Detectors to cover the
frequency range from 60 GHz to 600 GHz in 19 wide bands, in the focal plane of
a 1.2 m aperture telescope cooled at 40 K, allowing for an accurate extraction
of the CMB signal from polarized foreground emission. The projected CMB
polarization survey sensitivity of this instrument, after foregrounds removal,
is 1.7 \muKarcmin. The design is robust enough to allow, if needed, a
downscoped version of the instrument covering the 100 GHz to 600 GHz range with
a 0.8 m aperture telescope cooled at 85 K, with a projected CMB polarization
survey sensitivity of 3.2 \muKarcmin