ALFA Galactic Studies

Radio observations of the Milky Way are of vital importance for understanding what really occurs within galaxies. The unique sensitivity of Arecibo's 305m dish is now enhanced 7-fold with ALFA to provide an unprecedented new tool for the investigation of star formation and evolution, the recycling of material between stars and the interstellar medium (ISM), the large-scale transfer of energy among the different components of the ISM, and the evolution of elemental abundances over cosmic timescales. These phenomena can be observed with ALFA over the portion of the Galactic sky between declinations of -1.33 and +38.03 degrees, marked below in red.

The background image is 21cm line emission from neutral atomic hydrogen (H I). The line peak brightness is shown to emphasize high-latitude features. This all-sky map is from Kalberla et al. (2005), who combined 25m and 30m telescope observations from Dwingeloo and Argentina. Arecibo can observe about 32% of this area, but with 10 times the angular resolution and 5 times the velocity resolution in the H I line!

The ALFA sky coverage nicely complements the CGPS, VGPS, and SGPS components of the International Galactic Plane Survey shown in the map. ALFA can observe the Galactic disk in both the inner and outer Galaxy in the first and third quadrants, supplementing the superior IGPS angular resolution in the plane with better sensitivity and spectral resolution. And unlike the IGPS, Galactic ALFA surveys will also cover a large, continuous area off the plane, where isolated clouds and disk-halo energy exchanges can be studied.

ALFA is open to all telescope users through the normal proposal process. A consortium was formed in 2003 to conduct large surveys of the Galactic ISM with ALFA. The consortium is open to new members, but membership is not required to use ALFA. However, telescope users are encouraged to consult the documentation assembled by the consortium for general use.

One particular strength of ALFA is commensal observing, in which multiple backends can be used in parallel, enabling different science projects to use the same telescope pointing simultaneously. Commensal observing is especially powerful for sky surveys. A number of ALFA surveys are being observed commensally with each other to maximize the scientific return per hour of telescope time. The same option exists for smaller proposals.

Organization

To exploit the full mapping power of ALFA for Galactic ISM studies, the Galactic ALFA (GALFA) Consortium was formed in 2003. A set of guidelines governs the functioning of this consortium. Various tasks are assigned to working groups and coordinated via an adopted organizational scheme. The different types of observations and science that the Consortium plans to address are described in the following section on survey groups.

Membership

Membership in the GALFA Consortium is open to all interested parties irrespective of institutional affiliation, career level, expertise or scientific background. Individuals wishing to use ALFA for Galactic studies are not required to be members of the GALFA Consortium. However, anyone who wishes to contribute is encouraged to join. Most consortium members are associated with a particular survey group, as indicated in the current membership list. If you wish to join a GALFA project team (see list), please contact the relevant Principal Investigator.

Meetings

The GALFA Consortium has held 3 organizational meetings. The links below include presentations and other materials generated for each meeting.

	GALFA-1: 2003 March 21-23, Arecibo Observatory
	GALFA-2: 2003 June 18, Boston University
	GALFA-3: 2004 August 29, Arecibo Observatory

In addition to these general consortium meetings, the various GALFA sub-consortia concerned with specific surveys have regular teleconferences and occasional face-to-face meetings to discuss survey technical details, logistics, and science. For further information about these sub-consortia, please see the following section on survey groups.

Data Products and Availability

All GALFA Consortium data have a proprietary period of 18 months. The Consortium is responsible for subsequent production of finished data products of the completed surveys. These data products will be made publicly available through the National Virtual Observatory.

The GALFA White Paper (PDF) outlines the ISM science that the Consortium plans to pursue. This science will be addressed by three separate sub-consortia, each focused on a particular observational tracer of interstellar matter and processes. Brief descriptions of each group are given below. Please follow the links for further information.

H I 21cm Line Emission and Absorption (GALFA - H I)

Full-Stokes Radio Continuum Emission (GALFA - CON)

Radio Recombination Line Emission (GALFA - RRL)

As noted above, all GALFA data will be made publicly available after an 18-month proprietary period. This period is counted from the time that final data products are generated. Preliminary data products are for internal consortium use only. Exceptions may be made in the case of external collaborations approved by the relevant sub-consortium, with the proviso that the external parties are clearly aware that the data are not in their final state and are subject to change as pipeline processing is refined.

For specific details on data availability, potential users are encouraged to contact one of the following individuals:

	Galactic H I Line Data : Steven Gibson
	Full-Stokes Continuum Data : Russ Taylor
	Recombination-Line Data : Yervant Terzian

Although GALFA surveys are only just beginning, a number of exciting results have already emerged. The image above shows the first GALFA H I map. The links below give more details on this and several other results.

GALFA publications are listed below in reverse-chronological order. Two AAS special sessions have been devoted to ALFA and GALFA presentations.

Refereed Papers

	``Velocity Spectrum for H I at High Latitudes'', Chepurnov, A., Lazarian, A., Stanimirovic, S., Peek, J. E. G., & Heiles, C., submitted [astro-ph/0611462]
	``The Many Streams of the Magellanic Stream'', Stanimirovic, S., Hoffman, S., Heiles, C., Douglas, K. A., Putman, M., & Peek, J. E. G., 2008, ApJ, 680, 276 [arXiv:0802.1349]
	``A New Technique for Heterodyne Spectroscopy: Least-Squares Frequency Switching (LSFS)'', Heiles, C. 2007, PASP, 119, 643 [arXiv:0707.2399]
	``Reconstructing Deconstruction: High-Velocity Cloud Distance through Disruption Morphology'', Peek, J. E. G., Putman, M. E., McKee, C. F., Heiles, C., & Stanimirovic, S. 2006, ApJ, 656, 907 [astro-ph/0610429]
	``First Results from the Arecibo Galactic H I Survey: The Disk/Halo Interface Region in the Outer Galaxy'', Stanimirovic, S., Putman, M., Heiles, C., Peek, J. E. G., Goldsmith, P. F., Koo, B.-C., Krco, M. Lee, J.-J., Mock, J., Muller, E., Pandian, J. D., Parsons, A., Tang, Y., Werthimer, D. 2006, ApJ, 653, 1210 [astro-ph/0609137]

Conference Proceedings

	``Mapping Hydrogen in the Galaxy, Galactic Halo, and Local Group with ALFA: The GALFA-H I Survey Starting with TOGS'', Gibson, S. J., Douglas, K. A., Heiles, C., Korpela, E. J., Peek, J. E. G., Putman, M., & Stanimirovic, S. 2008, in The Evolution of Galaxies through the Neutral Hydrogen Window, at Arecibo Observatory, Puerto Rico, February 1-3; to be published in AIP conference proceedings, edited by R. Minchin & E. Momjian [arXiv:0805.0017v1]
	``A Sharper View of MBM 53-55 in GALFA H I Emission'', Gibson, S. J., Korpela, E. J., Stanimirovic, S., Heiles, C., Douglas, K. A., Peek, J. E. G., & Putman, M. 2007, Bull. A.A.S., 39, 988 [#211, #139.18] [Electronic Poster]
	``How Far Is the Tip of the Magellanic Stream?'', Stanimirovic, S., Hoffman, S., Heiles, C., Douglas, K., Putman, M., & Peek, J. 2007, Bull. A.A.S., 39, 988 [#211, #139.17]
	``The Many Streams of the Magellanic Stream'', Hoffman, S. M., Stanimirovic, S., Heiles, C., Douglas, K. A., Putman, M., & Peek, J. E. G. 2007, Bull. A.A.S., 39, 985 [#211, #139.04]
	``Halo Gas of M33'', Putman, M. E., Peek, J. E. G., Douglas, K. A., Heiles, C., Gibson, S. J., Korpela, E. J., & Stanimirovic, S., 2007, Bull. A.A.S., 40, ?? [#211, #095.34]
	``H I in Local Group Dwarf Galaxies'', Grcevich, J., Putman, M., & Peek, J. E. G. 2007, Bull. A.A.S., 39, 895 [#211, #095.07]
	``The Atomic Component of the Taurus Molecular Cloud Complex: Measurements and Implications'', Krco, M., Goldsmith, P. F., & Brown, R. L. 2007, Bull. A.A.S., 39, 780 [#211, #029.02]
	``Hidden Galactic Accretion: The Discovery of Low-Velocity Halo Clouds'', Peek, J. E. G., Putman, M. Sommer-Larsen, J., Heiles, C., Stanimirovic, S., Douglas, K., Gibson, S., & Korpela, E. J., 2007, Bull. A.A.S., 39, 760 [#211, #014.08]
	``Mapping the Galaxy in H I with GALFA'', Peek, J. E. G., Stanimirovic, S., Putman, M. E., Heiles, C., Douglas, K., Korpela, E., & Gibson, S. J., Mapping the Galaxy and Nearby Galaxies, Ishigaki Island, Okinawa, Japan, 2006 June 26-30
	``Recent Results from GALFA: `GoldenEye' on Disk/Halo Interfaces'', Stanimirovic, S. 2006, Bull. A.A.S., 38, 110 [#208, #34.02]
	``ALFA Surveys as Complements to Other Major Surveys'', Haynes, M. P. 2005, Bull. A.A.S., 37, 1489 [#207, #192.08], part of Special Session 192
	``GALFACTS: A Full-Stokes Continuum Survey of the Arecibo Sky'', Gibson, S. J. 2005, Bull. A.A.S., 37, 1489 [#207, #192.07], part of Special Session 192
	``GALFA-H I : The First 1000 Square Degrees'', Goldston, J. E., & GALFA-H I Consortium 2005, Bull. A.A.S., 37, 1489 [#207, #192.06], part of Special Session 192
	``Optimized Mapping Modes and Algorithms for ALFA'', Goldston, J. 2004, Bull. A.A.S., 36, 1476 [#205, #78.08], part of Special Session 205
	``GALFA Hardware and Calibration Techniques'', Heiles, C., Goldston, J., Mock, J., Parsons, A., Stanimirovic, S., & Werthimer, D. 2004, Bull. A.A.S., 36, 1476 [#205, #78.07], part of Special Session 205
	``Arecibo Survey of Radio Recombination Lines'', Terzian, Y. 2004, Bull. A.A.S., 36, 1476 [#205, #78.06], part of Special Session 205
	``A Full-Stokes ALFA Continuum Survey'', Taylor, A. R. 2004, Bull. A.A.S., 36, 1475 [#205, #78.05], part of Special Session 205
	``ALFA and HVCs: If Jodie Foster Knew What She Could Discover Now . . .'', Putman, M. E. 2004, Bull. A.A.S., 36, 1475 [#205, #78.04], part of Special Session 205
	``Using ALFA to Study H I and Molecular Clouds'', Arce, H. G., & GALFA-H I Consortium 2004, Bull. A.A.S., 36, 1475 [#205, #78.03], part of Special Session 205
	``A New Era of Galactic H I Science with ALFA'', Stanimirovic, S., & GALFA-H I Collaboration 2004, Bull. A.A.S., 36, 1475 [#205, #78.02], part of Special Session 205
	``Introduction to ALFA and the GALFA Consortium'', Goldsmith, P. F. 2004, Bull. A.A.S., 36, 1475 [#205, #78.01], part of Special Session 205

GALFA Memos and Documents

	Science Documents, Observing Proposals, and Consortium Policy
	Observing Procedures and Data Processing Software
	Hardware Details (Spectrometer Backends, etc.)

Other ALFA Memos and Documents

	General ALFA Technical Memos
	E-ALFA Memos and Documents
	P-ALFA Memos and Documents

Other Arecibo Materials

	Arecibo Technical Memos
	Arecibo Observatory Astronomy Reference Pages
	Phil Perillat's Arecibo Resources
	Arecibo Observatory 305m Telescope Schedule
	Control Interface Module for Arecibo (CIMA; telescope control software)

External Links

	U. Michigan - Turn On GALFA Survey (TOGS) website
	U. Calgary - Galactic ALFA Continuum Transit Survey (GALFACTS) website
	Arecibo Obs. - Inner Galaxy ALFA (I-GALFA) survey website

Project Details

For more details on a specific survey project, please contact that project's Principal Investigator:

	GALFA - H I : see the GALFA - H I projects table
	GALFA - CON : Russ Taylor
	GALFA - RRL : Yervant Terzian

General GALFA Information

For further information on GALFA generally, please contact Steven Gibson.