Archeops

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Archeops
Archeops gondola at launch.jpg
The Archeops gondola being launched
Alternative namesARCHEOPS Blue pencil.svg
Wavelength 143, 217, 353, 545 GHz (2.096, 1.382, 0.849, 0.550 mm)
First light 1999  Blue pencil.svg
Decommissioned2002  Blue pencil.svg
Telescope style Cosmic microwave background experiment
Radio telescope   Blue pencil.svg
Angular resolution 15 minute of arc  Blue pencil.svg
Website archeops.planck.fr Blue pencil.svg
[ edit on Wikidata]

Archeops was a balloon-borne instrument dedicated to measuring the Cosmic microwave background (CMB) temperature anisotropies. The study of this radiation is essential to obtain precise information on the evolution of the Universe: density, Hubble constant, age of the Universe, etc. To achieve this goal, measurements were done with devices cooled down at 100mK temperature placed at the focus of a warm telescope. To avoid atmospheric disturbance the whole apparatus is placed on a gondola below a helium balloon that reaches 40 km altitude.

Cosmic microwave background Electromagnetic radiation as a remnant from an early stage of the universe in Big Bang cosmology

The cosmic microwave background is electromagnetic radiation as a remnant from an early stage of the universe in Big Bang cosmology. In older literature, the CMB is also variously known as cosmic microwave background radiation (CMBR) or "relic radiation". The CMB is a faint cosmic background radiation filling all space that is an important source of data on the early universe because it is the oldest electromagnetic radiation in the universe, dating to the epoch of recombination. With a traditional optical telescope, the space between stars and galaxies is completely dark. However, a sufficiently sensitive radio telescope shows a faint background noise, or glow, almost isotropic, that is not associated with any star, galaxy, or other object. This glow is strongest in the microwave region of the radio spectrum. The accidental discovery of the CMB in 1964 by American radio astronomers Arno Penzias and Robert Wilson was the culmination of work initiated in the 1940s, and earned the discoverers the 1978 Nobel Prize in Physics.

Universe All of space and time and their contents

TheUniverse is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. While the spatial size of the entire Universe is unknown, it is possible to measure the size of the observable universe. In various multiverse hypotheses, auniverse is one of many causally disconnected constituent parts of a larger multiverse, which itself comprises all of space and time and its contents, or those with differing physical constants, or both.

Contents

Archeops has four bands in the millimeter domain (143, 217, 353 and 545 GHz) with a high angular resolution (about 15 arcminutes) in order to constrain small anisotropy scales, as well as a large sky coverage fraction (30%) in order to minimize the intrinsic cosmic variance.

Instrument and flights

The instrument was designed by adapting concepts put forward for the High Frequency Instrument of Planck surveyor (Planck-HFI) and using balloon-borne constraints. [1] Namely, it consists of an open 3He-4He dilution cryostat cooling spiderweb-type bolometers at 100 mK; cold individual optics with horns at different temperature stages (0.1, 1.6, 10 K) and an off-axis Gregorian telescope.

Bolometer

A bolometer is a device for measuring the power of incident electromagnetic radiation via the heating of a material with a temperature-dependent electrical resistance. It was invented in 1878 by the American astronomer Samuel Pierpont Langley.

The Gregorian telescope is a type of reflecting telescope designed by Scottish mathematician and astronomer James Gregory in the 17th century, and first built in 1673 by Robert Hooke. James Gregory was a contemporary of Isaac Newton, both often worked simultaneously on similar projects. Gregory's design was published in 1663 and pre-dates the first practical reflecting telescope, the Newtonian telescope, built by Sir Isaac Newton in 1668. However, Gregory's design was only a theoretical description and he never actually constructed the telescope. It was not successfully built until five years after Newton's first reflecting telescope.

The CMB signal is measured by the 143 and 217 GHz detectors while interstellar dust emission and atmospheric emission are monitored with the 353 (polarized) and 545 GHz detectors. The whole instrument is baffled so as to avoid stray radiation from the Earth and the balloon.

To cover as far as 30% of the sky, the payload was spinning mostly above the atmosphere, scanning the sky in circles with a fixed elevation of roughly 41 degrees. The gondola, at a float altitude above 32 km, spins across the sky at a rate of 2 rpm which, combined with the Earth rotation, produces a well sampled sky at each frequency.

Archeops flew for the first time in Trapani (Sicily) with four–hours integration time. Then, the upgraded instrument was launched three times from the Esrange base near Kiruna (Sweden) by the CNES during 2 consecutive Winter seasons (2001 and 2002). The last and best flight on Feb. 7th, 2002 yields 12.5 hours of CMB–type data (at ceiling altitude and by night) from a 19–hours total. The balloon landed in Siberia and it was recovered (with its precious data recorded on–board) by a Franco–Russian team with –40 deg.C. weather.

Results

Archeops CMB map Archeops last flight map.jpg
Archeops CMB map

Archeops has linked, for the first time and before WMAP, the large angular scales (previously measured by COBE) to the first acoustic peak region. [2] [3]

Cosmic Background Explorer space observatory

The Cosmic Background Explorer, also referred to as Explorer 66, was a satellite dedicated to cosmology, which operated from 1989 to 1993. Its goals were to investigate the cosmic microwave background radiation (CMB) of the universe and provide measurements that would help shape our understanding of the cosmos.

From its results, inflation motivated cosmologies have been reinforced with a flat Universe (total energy density Ωtot = 1 within 3%). When combined with complementary cosmological datasets regarding the value of Hubble's constant, Archeops gives constraints on the dark energy density and the baryonic density in very good agreement with other independent estimations based on supernovae measurements and big bang nucleosynthesis. [4]

Archeops has given the first polarized maps of the galactic dust emission with this resolution. [5] [6]

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References

  1. ↑ Benoît, A.; et al. (2002). "Archeops: A High Resolution, Large Sky Coverage Balloon Experiment for Mapping CMB Anisotropies". Astroparticle Physics . 17 (2): 101–124. arXiv: astro-ph/0106152 . Bibcode:2002APh....17..101B. doi:10.1016/S0927-6505(01)00141-4.
  2. ↑ Benoît, A.; et al. (2003). "The Cosmic Microwave Background Anisotropy Power Spectrum measured by Archeops". Astronomy and Astrophysics . 399 (3): L19. arXiv: astro-ph/0210305 . Bibcode:2003A&A...399L..19B. doi:10.1051/0004-6361:20021850.
  3. ↑ Tristram, M.; et al. (2005). "The CMB temperature power spectrum from an improved analysis of the Archeops data". Astronomy and Astrophysics . 436 (3): 785. arXiv: astro-ph/0411633 . Bibcode:2005A&A...436..785T. doi:10.1051/0004-6361:20042416.
  4. ↑ Benoît, A.; et al. (2003). "Cosmological constraints from Archeops". Astronomy and Astrophysics . 399 (3): L25. arXiv: astro-ph/0210306 . Bibcode:2003A&A...399L..25B. doi:10.1051/0004-6361:20021722.
  5. ↑ Benoît, A.; et al. (2004). "First Detection of Polarization of the Submillimetre Diffuse Galactic Dust Emission by Archeops". Astronomy and Astrophysics . 424: 571. arXiv: astro-ph/0306222 . Bibcode:2004A&A...424..571B. doi:10.1051/0004-6361:20040042.
  6. ↑ Ponthieu, N.; et al. (2005). "Temperature and polarization angular power spectra of Galactic dust radiation at 353 GHz as measured by Archeops". Astronomy and Astrophysics . 444 (1): 327. arXiv: astro-ph/0501427 . Bibcode:2005A&A...444..327P. doi:10.1051/0004-6361:20052715.
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