[meteorite-list] New Arecibo Receiver Triggers Quiet Revolution

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed Mar 8 13:10:01 2006
Message-ID: <200603081732.k28HWIs08738_at_zagami.jpl.nasa.gov>

http://www.news.cornell.edu/stories/March06/Arecibo.ALFA.lg.html

New Arecibo receiver triggers quiet revolution that could discover
20,000 galaxies and 1,000 pulsars

By Lauren Gold (lg34_at_cornell.edu)
Cornell University News Service
March 8, 2006

When the Arecibo L-Band Feed Array (ALFA) was installed on a misty
April morning two years ago, it promised to bring phenomenal new
sensitivity to the Arecibo Observatory.

Now, well into an ambitious series of comprehensive sky surveys using
the receiver, astronomers say ALFA is delivering spectacularly: both
by fulfilling the potential of the observatory's 1990s Gregorian
upgrade and ultimately by changing business as usual for researchers
worldwide.

The ALFA system of detectors and associated electronics, jointly
built by National Astronomy and Ionosphere Center (NAIC) and
Australian engineers, is slightly bigger than a washing machine and
has seven feeds -- making it essentially a giant seven-pixel radio
camera that allows researchers to image large swaths of sky and
search for such time-variable phenomena as pulsars seven times more
efficiently than in the past.

In just two years, ALFA has provided a wealth of new data, from
comets passing near the Earth and giant clouds of gas in our own
galaxy, to some of the most distant objects ever detected. It's a
quiet revolution -- but Jim Cordes, Cornell professor of astronomy
and one of the principal scientists behind ALFA's conception, says
the improvements are unparalleled.

"You could very well say it's a new phase for Arecibo," Cordes said.
"We're doing things that are pretty unique to what Arecibo can do --
playing on its strengths."

Cordes uses ALFA to find and observe pulsars, massive rapidly
spinning neutron stars that are ejected in stellar explosions, or
supernovae. The pulsar search could lead to a deeper understanding of
Einstein's theory of relativity.

"ALFA is going to discover probably 1,000 new pulsars that we haven't
seen yet," said former ALFA project manager Stephen Torchinsky. "The
expectation is that we're going to find some exotic objects. We could
use these systems to test the limits of the theory of relativity --
and at the most extreme cases, to find gravitational waves."

ALFA science is divided into three overarching surveys: the pulsar
survey, a survey for sources of neutral hydrogen in the Milky Way and
an extragalactic survey. In terms of sheer quantity of data, it is
providing an abundance, spurring scientists to come up with new ways
of sorting through and managing the constant torrent of information.

"It's like you have seven fire hoses of data coming at you," Cordes
said. "It's really a challenge to deal with."

That challenge is being met in part by scientists at the Cornell
Theory Center, who are creating a computer system to manage vast
amounts of data from such surveys as the Arecibo Legacy Fast ALFA
survey (ALFALFA), a broad extragalactic search for faint cosmic radio
signals from hydrogen clouds.

ALFALFA is expected to detect some 20,000 galaxies from as far away
as 750 million light years over the next six years. Astronomers hope
the survey will lead to the discovery of dark galaxies:
never-before-observed galaxies composed largely of dark matter and
hydrogen gas that could offer valuable information about the way
galaxies form and evolve.

"Without ALFA, a project like this could not have been done," said
Riccardo Giovanelli, Cornell professor of astronomy and ALFALFA
project leader. "It would have been too demanding on a few people."

But part of ALFA's value, say its users, is in the collaborative
style of research it invites. In the receiver's two years of
operation, the number of annual users at Arecibo has jumped by nearly
50 percent -- to 335 users in 2005 from 215 users in 2003. (Other
factors have been involved, but ALFA is credited with the majority of
the increase.) "We're bringing new users to Arecibo," said Martha
Haynes, Goldwin Smith Professor of Astronomy at Cornell and a member
of the ALFALFA team. Many are undergraduates -- evidence that the
receiver is energizing the next generation of astronomers.

Torchinsky, however, worries that ALFA's success could overpower
other research. "It's changed the culture a lot," he said, "but I
don't think it's entirely for the best. ALFA has begun to dominate
astronomy work being done at Arecibo ... making it more difficult for
individual proposals in general. Some good ideas have not been
developed because of this."

But others say the increase in users -- especially young ones --
makes it clear that the change is a good one. And they add that the
receiver's science will benefit researchers well beyond those
currently involved.

"The goal of the major surveys is to produce archival databases that
are accessible to all researchers and will be valuable resources for
many decades to come," said Robert Brown, director of the
Cornell-based NAIC, which manages the Arecibo Observatory for the
National Science Foundation.

It's part of a welcome trend, said Haynes.

"ALFA and the big surveys have changed the way science is being done
at Arecibo," she said. "It's exciting. It's challenging. This is the
modern way of doing astronomy."

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Received on Wed 08 Mar 2006 12:32:18 PM PST