ALFA: Radio Astronomy in the Multibeam Era The ALFA Project

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1 ALFA: Radio Astronomy in the Multibeam Era The ALFA Project Avinash Deshpande Senior Research Associate Radio Astronomy Group ALFA Scientific Coordinator

2 Arecibo L-Band Feed Array Will revolutionize our ability to survey the sky Brings new observing paradigm to NAIC

3 ALFA Front End 7 feed horns: 1 central + 6 on a ring stepped TE11 mode 25 cm diameter, 26 cm spacing Dewar rotation 200 degrees Polarization: dual linear (> 20 db isolation) Bandwidth: 300 MHz ( MHz) T(sys): 35 K (1.2 GHz) to 25 K (1.5 GHz)

4 ALFA Front End (cont) Beam size Central: 230 X 201 Ave pixel: 231 X 204 Total coverage: 768 X 658 ~25th of a square degree Gain Central: 11 K/Jy Other pixels: K/Jy

5 ALFA Feedhorns and Location in Dome

6 ALFA Front End Construction Contract with Australia Telescope National Facility/CSIRO to design and fabricate front end NAIC effort includes: - antenna controls - IF/LO system - backend(s) - data acquisition and archiving

7 ALFA Construction Schedule Purchase order for front end: r 2002 Delivery at AO expected: Apr 2004 IF/LO system: p 2003 Backends (H/W & S/W): end of 2003 WAPPS (100 MHz): Ap Se 4

8 ALFA Schedule (cont) Pre-commissioning phase -Apr 2004 Jan Test of 7 copies from single pixel Commissioning/integration -Sep 2004 Tests/calibration Sep-Dec 2004 Apr -In

9 Project Management

10 Project Management (cont) Hardware Cost: $ 1,210,000 Front-end Contract Value ($US): $ 713,964 Effort: 10 technical & 6 scientific staff involved ~9 FTE person-years Software Requirements: Control and data acquisition software are NAIC responsibility Data-reduction software will be developed entirely by the respective consortia, and will be made available to the AO and users.

11 Project Management (cont) Post Commissioning: The ALFA system will be maintained by the NAIC and scheduled observing runs by the consortia would begin. The first runs will be treated as test and the ALFA technical team will provide active support to resolve remaining difficulties. The NAIC Director will have input from the ALAC and the DMC. Development on additional back-ends may continue through Full piggy-backing only begins when the additional backends become available.

12 Project Management (cont) Regular local technical meetings Monthly telecons with CSIRO ALFA Advisory Committee Altschuler & Giovanelli Data Management Committee Venkataraman & Cordes

13 ALFA Advisory Committee Advise NAIC Director on ALFA time allocation policies, survey progress review process, consortia guidelines, hardware needs, and other issues Members: Daniel Altschuler (NAIC/AO) co-chair Riccardo Giovanelli (Cornell) co-chair Miller Goss (NRAO), liaison to Visiting Committee Rich Kron (U Chicago/SDSS) Joel Weisberg (Carleton) + Co-chair of Data Management Committee + Avinash Deshpande (ex-officio)

14 ALFA Science Consortia Pulsar (37) - meeting held Nov 1-2, 2002 Extragalactic HI (51) - meeting set for March 15-17, 2003 Galactic HI and continuum (50) - meeting set for March 19-20, 2003 SETI interested in piggy-backing (#): Number of prospective participants

15 ALFA Pulsar Consortium First meeting: Nov 1-2, attendees, international ALFA technical details by NAIC staff Survey parameters & strategies; time requirements Additional back-ends Data storage/porting; computing resources Post-processing (search) s/w; data products Follow-up observations Piggy-back surveys; prospects of parallel surveys Summary available on ALFA web page

16 ALFA Pulsar Consortium (cont) Consortium organization (3 hr session) - Coordination committee (8 members) - Chair elected (Jim Cordes) - Point of contact at AO (Paulo Freire) - Subgroups to work on different issues (5) - Action items Consortium report to NAIC (now available)

17 ALFA: Radio Astronomy in the Multibeam Era ALFA Surveys: A New Paradigm Chris Salter Senior Research Associate Head, Radio Astronomy Group Adjunct Professor of Astronomy

18 ALFA vs Single-Pixel Science Point & Shoot at specific unresolved targets Use the best available single-pixel system. Survey projects ALFA is ~7 times faster than an L-band single-pixel system. Surveying with ALFA Example: Meridian scans at elevation slew rate (2.5 deg/min) D e c (Zenith) R.A.

19 ALFA Will Discover 1000 New Pulsars Understand populations seen in radio and gamma ray bands Test notion that some pulsars are strange (quark) stars Exotic binaries Pulsar-pulsar Pulsar-black hole Test theories of binary evolution Test fundamental physics Survey simulations by J. Cordes, D. Chernoff, and Z. Arzoumanian

20 ALFALFA All-Sky Fast ALFA Survey Past surveys using Arecibo have given discrepant slopes for the faint end of the HI mass function, predicting number counts that differ by a factor of ten No other telescope can match Arecibo s sensitivity The best strategy is to survey a wide area of sky, but it is NOT necessary for this problem to integrate for more than about 5 sec/point

21 ALFALFA: A blind survey Even 1 sec integrations will detect thousands of galaxies ALFALFA will measure the faint end slope and may challenge models of the number and distribution of low mass halos nearby. Survey simulations by R. Giovanelli

22 ALFA: Survey of Virgo Cluster Discovery of optically faint HI rich dwarfs Probe of how gas content varies with local galaxy density Study of apparent filamentary structure (elongation) of cluster itself

23 Recombination Lines Continuu m HI

24 Piggyback ALFA survey Deep pulsar search Deep ZOA HI survey Galactic plane HI SETI A single survey providing data for multiple purposes will challenge hardware and software but optimize telescope usage.