physics4me

physicsgg

Posts Tagged ‘Planck

Revealing the Cosmic Microwave Background with Planck

leave a comment »


This animation illustrates the painstaking work performed by cosmologists in the Planck Collaboration to extract the Cosmic Microwave Background from the data collected by Planck. The first image in the sequence shows the sources of emission detected on the whole sky at the microwave and sub-millimetre wavelengths probed by Planck, which range from 11.1 mm to 0.3 mm (corresponding to frequencies between 27 GHz and 1 THz).
The different sources of emission include:
– discrete emission from individual galactic and extragalactic sources;
– diffuse radio emission from interstellar material in the Milky Way, which is mostly due to synchrotron radiation emitted by electrons that spiral along the lines of the Galactic magnetic field, but also comprises bremsstrahlung radiation, emitted by electrons that are slowed down in the presence of protons, as well as emission from spinning dust grains;
– diffuse emission due to the thermal emission from interstellar dust in the Milky Way;
– and, finally, the Cosmic Microwave Background.

The cosmologists had to remove all possible contamination due to emission by foreground sources before they could fully explore the Cosmic Microwave Background data and compare them to cosmological models.

Two CMB anomalous features hinted at by Planck’s predecessor, Nasa’s WMAP, are confirmed in the new high-precision data. One is an asymmetry in the average temperatures on opposite hemispheres of the sky (indicated by the curved line), with slightly higher average temperatures in the southern ecliptic hemisphere and slightly lower average temperatures in the northern ecliptic hemisphere. This runs counter to the prediction made by the standard model that the universe should be broadly similar in any direction we look. There is also a cold spot that extends over a patch of sky that is much larger than expected (circled). In this image the anomalous regions have been enhanced with red and blue shading to make them more clearly visible http://www.guardian.co.uk/science/picture/2013/mar/21/planck-most-detailed-map-universe-cosmic-microwave?CMP=twt_fd#zoomed-picture

Two CMB anomalous features hinted at by Planck’s predecessor, Nasa’s WMAP, are confirmed in the new high-precision data. One is an asymmetry in the average temperatures on opposite hemispheres of the sky (indicated by the curved line), with slightly higher average temperatures in the southern ecliptic hemisphere and slightly lower average temperatures in the northern ecliptic hemisphere. This runs counter to the prediction made by the standard model that the universe should be broadly similar in any direction we look. There is also a cold spot that extends over a patch of sky that is much larger than expected (circled). In this image the anomalous regions have been enhanced with red and blue shading to make them more clearly visible (guardian.co.uk)

Read more at http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=51551

Written by physicsgg

March 22, 2013 at 6:08 am

Planck All-Sky Images Show Cold Gas and Strange Haze

leave a comment »

All-sky image of molecular gas and three molecular cloud complexes seen by Planck
This all-sky image shows the distribution of carbon monoxide (CO), a molecule used by astronomers to trace molecular clouds across the sky, as seen by Planck.
Molecular clouds, the dense and compact regions throughout the Milky Way where gas and dust clump together, represent one of the sources of foreground emission seen by Planck. The vast majority of gas in these clouds consists of molecular hydrogen, and it is in these cold regions that stars are born. Since cold molecular hydrogen does not easily radiate, astronomers trace these cosmic cribs across the sky by targeting other molecules, which are present there in very low abundance but radiate quite efficiently. The most important of these tracers is CO, which emits a number of rotational emission lines in the frequency range probed by Planck’s High Frequency Instrument.
Emission lines affect a very limited range of frequencies compared to the broad range to which each of Planck’s detectors is sensitive, and are usually observed using spectrometers. But some CO lines are so bright, they actually dominate the total amount of light collected by certain detectors on Planck when they are pointed towards a molecular cloud.
This is the first all-sky map of CO ever compiled. The largest CO surveys thus far have concentrated on mapping the full extent of the Galactic Plane, where most clouds are concentrated, leaving large areas of the sky unobserved. Credits: ESA/Planck Collaboration
Read more: nasa.gov

Written by physicsgg

February 13, 2012 at 7:29 pm

Posted in ASTRONOMY, ASTROPHYSICS

Tagged with

The microwave sky after one year of Planck operations

leave a comment »

The nine Planck foreground full-sky maps

Aniello Mennella, for the Planck Collaboration
The ESA Planck satellite, launched on May 14th, 2009, is the third generation space mission dedicated to the measurement of the Cosmic Microwave Background (CMB), the first light in the Universe.
Planck observes the full sky in nine frequency bands from 30 to 857 GHz and is designed to measure the CMB anisotropies with an unprecedented combination of sensitivity, angular resolution and control of systematic effects. In this presentation we summarise the Planck instruments performance and discuss the main scientific results obtained after one year of operations in the fields of galactic and extragalactic astrophysics….
…. Read more: http://arxiv.org/PS_cache/arxiv/pdf/1110/1110.2051v1.pdf

Written by physicsgg

October 11, 2011 at 6:51 am