By Larry Klaes
Tau Zero journalist Larry Klaes here offers a look at a revolutionary telescope that will soon take our vision of the universe into new domains.
In the early half of the next decade, an instrument called the Cornell Caltech Atacama Telescope (CCAT) is planned to examine the Universe through a less-studied region of the electromagnetic spectrum from an observatory in the remote deserts of Chile higher than any current major ground-based facility.
CCAT is the culmination of plans by Cornell University and the California
Institute of Technology (Caltech) initiated in 2004 to jointly conduct submillimeter astronomy with the largest telescope ever conceived for such an endeavor. The 25-meter (82-foot) wide mirror of the CCAT will allow astronomers to see the Cosmos in the area between the infrared and radio realms of the electromagnetic spectrum, an area well beyond the region that is visible to human eyes.
The moisture in Earth’s atmosphere normally blocks light waves coming at our planet from the submillimeter region. This is why CCAT will be built at 18,400 feet atop a dormant volcano named Cerro Chajnantor in Chile’s Atacama Desert. This region of South America is so dry and desolate that robotic Mars rovers have been tested there to approximate conditions on the Red Planet – nearly ideal for a telescope studying the submillimeter wavelengths.
Among the celestial objects astronomers want to study in this realm are
galaxies, especially the ones which formed not long after the Big Bang which created our Universe 13.7 billion years ago, and stars in our Milky Way galaxy with encircling debris disks that may be forming new planets. Even icy bodies in the Kuiper Belt of our outer Solar System will be explored by CCAT to understand how Earth and our neighboring worlds came to be five billion years in the past.
Image: An artist’s rendering of the proposed Cornell Caltech Atacama Telescope that will be built in the Cerro Chajnantor in the Atacama Desert region in Chile. Credit: Cornell University/CCAT.
CCAT will also investigate the mysterious dark matter that makes up the vast majority of the mass in the Universe. Understanding what this material is and how it interacts with clusters of galaxies is of paramount importance to science. The telescope will also look at the equally mysterious dark energy that is apparently causing our reality to expand at an ever-increasing rate.
What will become of our Universe as the galaxies recede from each other is another major goal of understanding for science. For example, the vast islands of stars we call galaxies formed from major clouds of dust and gas. Radiation from these new galaxies was absorbed by all the dust and later re-emitted at longer wavelengths on the electromagnetic spectrum. The radiation was “stretched” to even longer wavelengths as the Universe expanded and galaxies moved further apart from each other until it reached Earth in the submillimeter range. Until recent years and advances in technology, this wavelength was mostly invisible to ground-based telescopes due to its absorption by the aforementioned water that permeates our atmosphere.
The current crop of smaller submillimeter telescopes observe objects in
space a few hundred pixels at one time. CCAT, operating thirty times faster and with a mirror twice as large as its brethren, will observe tens of thousands and eventually millions of pixels at once, creating a clearer picture in the submillimeter realm of the denizens of our Cosmos than ever before.
Complementing CCAT is what will become a collection of eighty large antennae currently being built two thousand feet below the submillimeter telescope’s projected site on Cerro Chajnantor. The Atacama Large Millimeter Array (ALMA) is an interferometer to be operated as a public facility by the National Radio Astronomy Observatory (NRAO) to study the Universe in spectra that include the submillimeter. ALMA will make highly detailed maps of particular regions of space. An image made by CCAT will cover an area of the sky thousands of times larger. Objects of special interest imaged by CCAT will later be examined by ALMA to discern them in finer detail.
The construction of CCAT is expected to begin next year. The first
observations with the telescope are hoped to begin in 2012, with CCAT
becoming fully operational by 2014, about the same time as ALMA.
For more information on CCAT, go here to read the paper presented at the 18th International Symposium on Space Terahertz Technology.
Comments on this entry are closed.
Space radio telescope will be launched very soon.
RadioAstron project is an international collaborative mission to launch a free flying satellite carrying a 10-meter radio telescope in high apogee orbit around the Earth. Launch of the spacecraft is scheduled for 2007. The aim of the mission is to use the space telescope to conduct interferometer observations in conjunction with the global ground radio telescope network in order to obtain images, coordinates, motions and evolution of angular structure of different radio emitting objects in the Universe with the extraordinary high angular resolution.
The orbit of RadioAstron satellite will have apogee radius in the range up to 350 000 km. The spacecraft’s operational lifetime will be no less than five years. Space-ground Very Long Baseline Interferometer (VLBI) measurements with this orbit will provide morphological and coordinate information on galactic and extragalactic radio sources with fringe size up to 8 micro arc second at the shortest wavelength 1.35 cm.
Nice work Larry!
Sub-millimeter/T-ray wavelengths have been hard to observe and generate until some pretty recent advances. The potential for discovery is immense.
I m sure that this new telescope will reveal many new and surprising things about the universe. But as far as dark mater and dark energy goes I am quite skeptical. It makes up most of the universe but we can’t detect it in a laboratory? Sure astronomers needed to create it because the current paradigm does not explain the evidence gathered by telescopes. Rather than rethinking their basic assumptions they math-terbated for a while and came up with dark matter, but that wasn’t enough to fit the evidence so theoretical astronomers math-terbated some more and came up with dark energy in the hope that it will provide the ad hoc solution for a failing paradigm. How much you want to bet that the evidence gathered by new telescopes like this will require the creation of another ad hoc theoretical invention? Maybe they will call it dark either.
Dark mass is the only option if you don’t modify gravity. Dark energy is more model dependent, but there does seem to be an acceleration of the galaxies that doesn’t fit unless there is a cosmological constant.
Now which unwarranted assumption is the better choice of the two? Unseen mass that is only noticed by its gravity, energy that is only known by its acceleration, or some utterly ad hoc fix to gravity as we-know-it from ever more precise measurements in our Solar System? One assumes mass & energy as yet unseen, except by its gravitational effects, and the other assumes an otherwise unsupported fiddling with gravity.
Remember dark mass is OBSERVED – it’s just unexplained. Likewise dark energy. Both come from real observations, not epicycles to fit a theoretical ideal. Cosmologists would rather do without both.
Now I think there may be something to the idea of MOND, at least in its fully relativistic version, but MOND is more likely to be an epicycle than unseen mass. At least we know there can be unseen particles – neutrinos for example, or other things like them – but we don’t have any other reason to think gravity needs modifying.
Any other explanation just hasn’t engaged the data seriously.
If someone would build a dark matter detector or a dark energy antenna I would drop my skepticism. (For example neutrino detectors have been built and they have detected neutrinos)
Dark mass has not been observed, its existence has been inferred from observations. The most common example that I have read about concerns the shape of galaxies. There is not enough gravity from visible matter in the Milky Way to keep it from breaking apart. The assumption in the current paradigm is that gravity is only force that operates on astronomical scales. So to hold the galaxy together astronomers invented dark matter rather than reexamine their assumptions. There is evidence that electromagnetic forces are also operating on astronomical scales.
Electromagnetic forces aren’t strong enough to move stars – unless you believe the electric universe nonsense of Thornhill and co. The kind of charge levels needed to move stars require ridiculous amounts of charge separation which require a huge energy input – from where? Dark energy? Unwarranted assumption after unwarranted assumption – they multiply when you head down such cranky imaginary physics.
Sure magnetic fields have a role to play and they exist in intergalactic space, but galactic rotation curves can’t be explained by them, no way. That was one fundamental flaw in Eric Lerner’s discussion of dark mass which led me to reject the Plasma Universe he advocates – that and other inaccuracies. Magnetic fields DO play a big role in star formation as they de-spin the protostar, thus allowing the planets to form. They probably have a role in the formation history of star-forming regions too, but they don’t explain the rotation curves.
Thanks for the reply, I don’t want to head down a pathway of cranky imaginary physics, which is why I am skeptical of dark matter and dark energy. We should be able to build detectors for them not just infer their existence, right? Other than their gravitational effects there should be some other quality to dark matter and dark energy that should allow us to detect them.
I know that the following is a weak argument by analogy but the shape of the milky way does resemble the heliospheric current. Are astronomers sure that there isn’t a galactic analog to the heliospheric current? Couldn’t that provide the energy to alter the movement of stars?
the link above gives an animation of the heliospheric current. ( I know my question about a galactic current may be ignorant but I hope its not stupid ;-)
What’s the problem with gravitational effects? There are, for example, search strategies ongoing that utilize the estimated position, movement and mass of lumps of dark matter to statistically evaluate gravitational lensing events over extragalactic dense star fields (Magellanic Clouds). Seems like good science to me. How else do you propose to detect this stuff that doesn’t radiate photons (except cold thermal radiation at about the temperature of the CMB)?
And if it’s some form of exotic matter, the interaction with ordinary matter must be exceptionally weak (or we’d know about it by now!). Even so there are people coming up with direct detection strategies. There is something about this in Wikipedia but I didn’t read it in detail.
The solar wind’s flow is a spiral that is flowing outwards while it is also rotating. The spiral arms of galaxies aren’t outflows – that would be measurable the same way their rotation curves are and it’s just not seen. Stars are also too massive compared to galactic fields to be influenced in anyway – gas clouds and star forming regions are a different story, but spiral arms have been successfully modeled via gravitational simulation. Some spirals are caused by tidal forces between two galaxies, but others are just transient patterns that form, fade and reform. They’re not perfectly understood in all their forms, but that’s because galaxies have billions of stars and computers can only simulate a few hundred thousand at a time. But the flat rotation curves that tell us dark matter or MOND are needed are seen in the whole of the galactic disks, not just the arms.
Many galaxies with large amounts of invisible mass aren’t spirals at all and show no discernible electromagnetic influences. Galactic jets are definitely controlled and produced by electromagnetic processes, but the rest of galactic behaviour seems entirely gravitational – either invisible mass or MOND-style modifications. Polarisation of light and other em radiation can also trace the structure and even the strength of galactic fields – what measurements we have so the fields just aren’t strong enough to substitute for extra gravity.
Thanks Adam and Ron,
I will certainly tone down my skepticism of the “dark stuff” and keep and an eye out for results from the dark matter detectors that are being developed. I am not 100% convinced but I am at least 75% less skeptical of the standard explanations.
Well that sounds more like the right mix. No breakthroughs in science are ever made by being too accepting of the consensus. If you’re willing to learn more and question what any source tells you – weighing it up instead of just rejecting it or accepting it too readily – then my efforts at informing you have paid off. Astronomers aren’t idiots collectively that they’re willing to believe any old idea. Both dark matter and MOND have been argued over and analysed for years. Galaxy rotation curves and cluster masses have been a puzzle for decades. Dark energy is only a new discovery, but the data is pretty compelling to those in the know. As a rule astronomers try not to believe any old idea that occurs to them – they first of all want data and good reasons for believing what it’s telling them.
After 10 years, we still can’t find most of the universe
‘Dark energy’ is real, scientists say, though they don’t know what it is
By ROBERT S. BOYD
Sept. 29, 2007, 11:02PM
WASHINGTON — Ten years ago, an unexpected astronomical discovery stunned the scientific world: Two rival teams of astrophysicists claimed that most of the universe is made of an invisible substance they called “dark energy.” Only a tiny fraction, they said, consists of the ordinary atoms that make up stars, chairs and people.
Dark energy has shaken the fields of physics and astronomy, much as Copernicus did 500 years ago when he declared that the Earth revolved around the sun, not the other way around.
The astronomers who made that astonishing claim say their findings have been confirmed repeatedly and made more precise. But they confess that no one — including them — understands what this mysterious dark energy is.
“We don’t know any more today than we did 10 years ago,” Saul Perlmutter, the leader of one of the discovery teams, said at an anniversary conference this month sponsored by NASA.
Mario Livio, a theorist at the Space Telescope Science Institute, a NASA affiliate in Baltimore, said it was shocking to realize that “we don’t have an explanation for 74 percent of everything there is.”
“We need humility,” Livio said. “It’s as if we had no idea what water is, even though water covers three-quarters of the Earth.”
Full article here:
ALMA Project News
High resolution images are available at
A Colossus Gets its Name
Today, the first of the two ALMA antenna transporters was given its
name at a ceremony on the compounds of the manufacturer, the heavy-
vehicle specialist Scheuerle Fahrzeugfabrik GmbH, in Baden-
Wuerttemberg. The colossus, 10 metres wide, 20 metres long and 6
metres high, will be shipped to Chile by the end of the month. The
second one will follow in a few weeks.
The transporter was named ‘Otto’ in honour of Otto Rettenmaier, the
owner of the Scheuerle company. “The rather unusual move to name a
vehicle is a recognition of the remarkable achievement these unique
machines represent,” said Hans Rykaczewski, the European ALMA Project
Manager. “Their sizes alone would justify using superlatives to
describe them. But they are also outstanding as they will operate at
5000 metres altitude, where the air is rare, and they have to be able
to place 115-ton antennas with a precision of a few millimetres,” he
“The ALMA antenna transporters are the proof of the excellence of our
staff and of our ability to build heavy vehicles that are at the
limits of the possible,” said Otto Rettenmaier. “Never in the history
of our company have we had to comply with such exceptional
requirements on material and techniques as we had to do with these
machines. We are proud as a company to have been able to contribute
with such an exceptional piece of technology for astronomical research.”
The ALMA Project, in which ESO leads the construction and the
operations on behalf of Europe, is a giant, international observatory
currently in construction on the high-altitude Chajnantor site in
Chile, which will be composed initially of 66 high-precision
telescopes, operating at wavelengths of 0.3 to 9.6 mm. The ALMA
antennas will be electronically combined and provide astronomical
observations which are equivalent to a single large telescope of
tremendous size and resolution.
The 66 antennas of the array can be placed on 192 different pads,
covering antenna configurations as compact as 150 metres to as wide
as 15 kilometres. Changing the relative positions of the antennas and
thus also the configuration of the array allows for different
observing modes, comparable to using a zoom lens on a camera.
Given their important functions, both for the scientific work and in
transporting high-tech antennas with the required care, the vehicles
must live up to very demanding operational requirements. To address
these, Scheuerle has developed and built two very special
transporters. Building heavy vehicles able to transport with great
precision 115-ton antennas is not a problem per se for this company,
which specialises in building huge transporters. The problem however
was to produce a vehicle able to operate at such a high altitude,
where the two engines will lose about half of their power (compared
to sea level) because of the reduced oxygen content of the air. With
their two 500 kW diesel engines (nearly as much as two Formula 1
engines), the ALMA transporters will be able to move at the speed of
20 km/h when empty and 12 km/h when loaded with an antenna.
Notwithstanding its impressive dimensions, the transporter can be
manoeuvred by a single operator, the precise positioning being made
possible by a hydrostatic system while the electronic 28-wheel drive
allows very precise motions.
“When completed in 2012, ALMA will be the largest and most capable
imaging array of telescopes in the world,” said Massimo Tarenghi, the
ALMA Director. “The ALMA antenna transporters, which are unique
technological jewels, beautifully illustrate how we are actively
progressing towards this goal.”
ALMA will be able to probe the Universe at millimetre and
submillimetre wavelengths with unprecedented sensitivity and
resolution, with an accuracy up to ten times better than the Hubble
Space Telescope, and complementing images made with ESO’s Very Large
ALMA will be the forefront instrument for studying the cool universe
– the relic radiation of the Big Bang, and the molecular gas and dust
that constitute the very building blocks of stars, planetary systems,
galaxies, and life itself.
Because ALMA will observe in the millimetre and submillimetre
wavelengths the atmosphere above the telescope must be transparent.
This requires a site that is high and dry. ALMA will thus be
installed at the 5000m high plateau of Chajnantor in the Atacama
Desert of Chile, the world’s driest area – the next best location to
outer space for these high-accuracy astronomical observations.
The ALMA project is a partnership between Europe, East Asia and North
America in cooperation with the Republic of Chile. ALMA is funded in
Europe by ESO, in East Asia by the National Institutes of Natural
Sciences of Japan in cooperation with the Academia Sinica in Taiwan
and in North America by the U.S. National Science Foundation in
cooperation with the National Research Council of Canada. ALMA
construction and operations are led on behalf of Europe by ESO, on
behalf of East Asia by the National Astronomical Observatory of Japan
and on behalf of North America by the National Radio Astronomy
Observatory, which is managed by Associated Universities, Inc.
ESO, Garching, Germany
The impact of main belt asteroids on infrared–submillitmetre photometry and sources counts
Authors: Cs. Kiss, A. Pal, Th.G. Mueller, P. Abraham
(Submitted on 24 Nov 2007)
Abstract: Among the components of the infrared and submillimetre sky background, the closest layer is the thermal emission of dust particles and minor bodies in the Solar System. This contribution is especially important for current and future infrared and submillimetre space instruments –like those of Spitzer, Akari and Herschel — and must be characterised by a reliable statistical model.
We describe the impact of the thermal emission of main belt asteroids on the 5…1000um photometry and source counts, for the current and future spaceborne and ground-based instruments, in general, as well as for specific dates and sky positions.
We used the statistical asteroid model (SAM) to calculate the positions of main belt asteroids down to a size of 1km, and calculated their infrared and submillimetre brightness using the standard thermal model. Fluctuation powers, confusion noise values and number counts were derived from the fluxes of individual asteroids.
We have constructed a large database of infrared and submillimetre fluxes for SAM asteroids with a temporal resolution of 5 days, covering the time span January 1, 2000 — December 31, 2012. Asteroid fluctuation powers and number counts derived from this database can be obtained for a specific observation setup via our public web-interface.
Current space instruments working in the mid-infrared regime (Akari and Spitzer Space Telescopes) are affected by asteroid confusion noise in some specific areas of the sky, while the photometry of space infrared and submillimetre instruments in the near future (e.g. Herschel and Planck Space Observatories) will not be affected by asteroids. Faint main belt asteroids might also be responsible for most of the zodiacal emission fluctuations near the ecliptic.
Comments: accepted for publication in Astronomy & Astrophysics; Additional material (appendices) and the related web-interface can be found at: “this http URL”
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0711.3824v1 [astro-ph]
From: Csaba Kiss [view email]
[v1] Sat, 24 Nov 2007 08:22:42 GMT (339kb)
High-resolution radio observations of submillimetre galaxies
Authors: A. D. Biggs, R. J. Ivison (Edinburgh)
(Submitted on 18 Dec 2007)
Abstract: We have produced sensitive, high-resolution radio maps of 12 SMGs in the Lockman Hole using combined MERLIN and VLA data at a frequency of 1.4 GHz. Integrating for 350hr yielded an r.m.s. noise of 6.0 uJy/beam and a resolution of 0.2-0.5″. For the first time, wide-field data from the two arrays have been combined in the (u,v) plane and the bandwidth smearing response of the VLA data has been removed. All of the SMGs are detected in our maps as well as sources comprising a non-submm luminous control sample. We find evidence that SMGs are more extended than the general uJy radio population and that therefore, unlike in local ULIRGs, the starburst component of the radio emission is extended and not confined to the galactic nucleus. For the eight sources with redshifts we measure linear sizes between 1 and 8 kpc with a median of 5 kpc. Therefore, they are in general larger than local ULIRGs which may support an early-stage merger scenario for the starburst trigger. X-rays betray AGN in six of the 33 sources in the combined sample. All but one of these are in the control sample, suggesting a lower incidence of AGN amongst the submm-luminous galaxies which is, in turn, consistent with increased X-ray absorption in these dust-obscured starbursts. Only one of our sources is resolved into multiple, distinct components with our high-resolution data. Finally, compared to a previous study of faint radio sources in the GOODS-N field we find systematically smaller source sizes and no evidence for a tail extending to ~4″. Possible reasons for this are discussed.
Comments: In press at MNRAS. 12 pages. High-resolution PDF version available at this http URL
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0712.3047v1 [astro-ph]
From: Rob Ivison [view email]
[v1] Tue, 18 Dec 2007 21:00:16 GMT (373kb)
Chemical and thermal structure of protoplanetary disks as observed with ALMA
Authors: D. Semenov (1), Ya. Pavlyuchenkov (1), Th. Henning (1), S. Wolf (1), R. Launhardt (1) ((1) Max Planck Institute for Astronomy, Heidelberg, Germany)
(Submitted on 9 Jan 2008)
Abstract: We predict how protoplanetary disks around low-mass young stars would appear in molecular lines observed with the ALMA interferometer. Our goal is to identify those molecules and transitions that can be used to probe and distinguish between chemical and physical disk structure and to define necessary requirements for ALMA observations. Disk models with and without vertical temperature gradient as well as with uniform abundances and those from a chemical network are considered. As an example, we show the channel maps of HCO$^+$(4-3) synthesized with a non-LTE line radiative transfer code and used as an input to the GILDAS ALMA simulator to produce noise-added realistic images. The channel maps reveal complex asymmetric patterns even for the model with uniform abundances and no vertical thermal gradient. We find that a spatial resolution of $0.2-0.5\arcsec$ and 0.5–10 hours of integration time will be needed to disentangle large-scale temperature gradients and the chemical stratification in disks in lines of abundant molecules.
Comments: 4 pages, 3 figures, 1 table, accepted for publication to ApJ Letters
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0801.1463v1 [astro-ph]
From: Dmitry Semenov [view email]
[v1] Wed, 9 Jan 2008 16:43:41 GMT (604kb)
Clarifying the Nature of the Brightest Submillimetre Sources via SMA Interferometry
Authors: J. D. Younger, J. S. Dunlop, A. B. Peck, R. J. Ivison, A. D. Biggs, E. L. Chapin, D. L. Clements, S. Dye, T. R. Greve, D. H. Hughes, D. Iono, I. Smail, M. Krips, G. R. Petitpas, D. Wilner, A. M. Schael, C. D. Wilson
(Submitted on 18 Jan 2008)
Abstract: We present high-resolution interferometric imaging of LH850.02, the brightest 850- and 1200-um submillimetre (submm) galaxy in the Lockman Hole, at 890um with the Submillimetre Array (SMA). Our high-resolution submm imaging detects LH850.02 at greater than 6-sigma as a single compact (size less than 1 arcsec or less than 8 kpc) point source and yields its absolute position to ~0.2-arcsec accuracy. LH850.02 has two alternative radio counterparts within the SCUBA beam (LH850.02N & S), both of which are statistically very unlikely to be so close to the SCUBA source position by chance. However, the precise astrometry from the SMA shows that the submm emission arises entirely from LH850.02N, and is not associated with LH850.02S (by far the brighter of the two alternative identifications at 24-um). Fits to the optical-infrared multi-colour photometry of LH850.02N & S indicate that both lie at z~3.3, and are therefore likely to be physically associated. At these redshifts, the 24um-to-submm flux density ratios suggest that LH 850.02N has an Arp 220-type starburst-dominated far-IR SED, while LH 850.02S is more similar to Mrk 231, with less dust-enshrouded star-formation activity, but a significant contribution at 24-um (rest-frame ~5-6um) from an active nucleus. This complex mix of star-formation and AGN activity in multi-component sources may be common in the high redshift ultraluminous galaxy population, and highlights the need for precise astrometry from high resolution interferometric imaging for a more complete understanding.
Comments: submitted to MNRAS
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0801.2764v1 [astro-ph]
From: Joshua Younger [view email]
[v1] Fri, 18 Jan 2008 20:21:31 GMT (81kb)
Submillimeter Spectrum of Formic Acid
Authors: Valerio Lattanzi, Adam Walters, Brian J. Drouin, John C. Pearson
(Submitted on 22 Jan 2008)
Abstract: We have measured new submillimeter-wave data around 600 GHz and around 1.1 THz for the 13C isotopologue of formic acid and for the two deuterium isotopomers; in each case for both the trans and cis rotamer. For cis-DCOOH and cis-HCOOD in particular only data up to 50 GHz was previously available. For all species the quality and quantity of molecular parameters has been increased providing new measured frequencies and more precise and reliable frequencies in the range of existing and near-future submillimeter and far-infrared astronomical spectroscopy instruments such as Herschel, SOFIA and ALMA.
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0801.3422v1 [astro-ph]
From: Valerio Lattanzi [view email]
[v1] Tue, 22 Jan 2008 16:59:34 GMT (1037kb)
Prospects for AGN studies with ALMA
Authors: R. Maiolino
(Submitted on 4 Jun 2008)
Abstract: These lecture notes provide an introduction to mm/submm extragalactic astronomy, focused on AGN studies, with the final goal of preparing students to their future exploitation of the ALMA capabilities.
I first provide an overview of the current results obtained through mm/submm observations of galaxies and AGNs, both local and at high redshift. Then I summarize the main mm/submm facilities that are currently available. ALMA is then presented with a general description and by providing some details on its observing capabilities. Finally, I discuss some of the scientific goals that will be achievable with ALMA in extragalactic astronomy, and for AGN studies in particular.
Comments: 42 pages, 21 figures, Lecture notes for the school “AGN at the highest angular resolution: theory and observations” (Torun), eds. A. Marconi and A. Niedzielski
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0806.0695v1 [astro-ph]
From: Roberto Maiolino [view email]
[v1] Wed, 4 Jun 2008 05:29:55 GMT (1203kb)
The Atacama Desert -World’s Space-Observatory Headquarters
The lunar landscapes of Chile’s Atacama Desert, which stretches for about 650 miles along the Pacific Ocean to the Peruvian Border, is generally considered the driest place on earth, wedged between the rain shadows of the Andes to the east and the coast ranges to the west, while the cold Humboldt Current off the coast suppresses evaporation from the ocean. There are places in the Atacama where there has been no recorded or observed rainfall in the 400+ years since the Spaniards first arrived.
The Atacama Desert’s dry climate and 5,600-meter (about 3.5 miles) altitude make it a unique and ideal mecca for both ground-based reflector and far-infrared astronomy. It’s the next best location to outer space for high-accuracy astronomical observations. The southern hemisphere skies were opened with the construction of the Carnegie 100-inch DuPont telescope at Las Campanas in 1977.
Thirty years later, Cornell and Caltech have announced the “Atacama Telescope Project To Revolutionize Astronomy,” a proposed 25-meter aperture telescope that will be the largest, most precise and highest astronomical facility in the world.
The $100 million Cornell Caltech telescope, to be built in the Cerro Chajnantor region, will take advantage of the rapid development in bolometer array technology (instruments that measures radiant energy) to answer some of the most fundamental questions of cosmology. Radiation at sub-millimeter wavelengths (longer than visible light but shorter than radio waves) is normally difficult to detect from the ground because it is easily absorbed by water in the Earth’s atmosphere. Situating the telescope in the dry Atacama climate eliminates this problem.
Full article here:
Two ALMA radio telescopes pass a major test by working together to
image the planet Mars:
The Atacama Cosmology Telescope: Evidence for Dark Energy from the CMB Alone
Authors: Blake D. Sherwin, Joanna Dunkley, Sudeep Das, John W. Appel, J. Richard Bond, C. Sofia Carvalho, Mark J. Devlin, Rolando Dunner, Thomas Essinger-Hileman, Joseph W. Fowler, Amir Hajian, Mark Halpern, Matthew Hasselfield, Adam D. Hincks, Renee Hlozek, John P. Hughes, Kent D. Irwin, Jeff Klein, Arthur Kosowsky, Tobias A. Marriage, Danica Marsden, Kavilan Moodley, Felipe Menanteau, Michael D. Niemack, Michael R. Nolta, Lyman A. Page, Lucas Parker, Erik D. Reese, Benjamin L. Schmitt, Neelima Sehgal, Jon Sievers, David N. Spergel, Suzanne T. Staggs, Daniel S. Swetz, Eric R. Switzer, Robert Thornton, Katerina Visnjic, Ed Wollack
(Submitted on 2 May 2011)
Abstract: For the first time, measurements of the cosmic microwave background radiation (CMB) alone favor cosmologies with $w=-1$ dark energy over models without dark energy at a 3.2-sigma level. We demonstrate this by combining the CMB lensing deflection power spectrum from the Atacama Cosmology Telescope with temperature and polarization power spectra from the Wilkinson Microwave Anisotropy Probe. The lensing data break the geometric degeneracy of different cosmological models with similar CMB temperature power spectra. Our CMB-only measurement of the dark energy density $\Omega_\Lambda$ confirms other measurements from supernovae, galaxy clusters and baryon acoustic oscillations, and demonstrates the power of CMB lensing as a new cosmological tool.
Comments: 4 pages, 3 figures
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO)
Cite as: arXiv:1105.0419v1 [astro-ph.CO]
From: Blake Sherwin [view email]
[v1] Mon, 2 May 2011 19:52:29 GMT (181kb)