The Arecibo Zone of Avoidance Survey (ALFAZOA)

The Extragalactic ALFA Zone of Avoidance team is mapping the distribution of low-Galactic-latitude galaxies and large scale structures through detection of galaxies' 21-cm emission with ALFA. This Zone of Avoidance (ZOA) survey finds new HI galaxies which lie hidden behind the Milky Way, and also provides redshifts and other HI parameters for partially-obscured galaxies known at other wavelengths. In this way, we are illuminating the large scale structure in the local Universe in the low-Galactic-latitude sky where it is currently poorly mapped. The ZOA survey is one of the Extragalactic ALFA projects, and proceeds in tandem with Galactic ALFA and Pulsar ALFA projects. This "commensal" style of observing, using multiple backends simultaneously, increases enormously the scientific throughput of the telescope, making very efficient use of observing hours, particularly important during the popular Galactic time. The survey proceeds in two phases: shallow and deep.

Results from the Shallow Survey

The observations for the shallow survey (rms ~5-7 mJy) are complete, and were conducted in commensal mode with Galactic ALFA projects, mapping about 1000 square degrees, 30° ≤ l ≤ 75°, |b| ≤ 10°. We have cataloged about 450 galaxies, including previously unrecognized dwarfs (McIntyre et al. 2011).

Sources from the ALFA ZOA shallow survey

Figure: Galaxies revealed by the ALFA ZOA shallow survey (blue circles) shown with previously-known LEDA galaxies within 12,000 km/s, and galaxies from low-Galactic-latitude Parkes surveys (red points).

The ALFAZOA deep survey

We are surveying the ZOA in both the inner (30° ≤ l ≤ 75°) and outer (175° ≤ l ≤ 210°) Galaxy, with Pulsar and Galactic Radio Recombination Line commensal partners. The effective integration time for the deep survey is 5 minutes per beam, reaching 1 mJy rms. The higher sensitivity and increased velocity coverage of this deep phase puts us on track to detect about 1500 galaxies over the ZOA, including low HI mass objects in the local universe, and HI galaxies at large distances. Galaxies with recession velocities near 20,000 km/s have been discovered in our first completed field, 15 square degrees centered at l = 192°, b = -2°.

Detectability of HI galaxies in the ALFA 
ZOA surveys

Figure: Curves show predicted sensitivity to HI mass for the shallow and deep surveys, assuming 6 σ detection of a galaxy with 200 km/s linewidth. Actual detections to date are overlaid. The deep detections are from a completed 15 square degree field in the outer Galaxy, a small fraction of the total area to be observed. The gap at ~16,000 km/s is due to RFI.

We are able to trace large-scale structure to large distances across the plane in this region. The wedge plot shows how our survey continues the mapping of known large-scale sturcutres behind the Milky Way, and discovers new features.

Wedge plot from the deep survey

Figure: ALFA ZOA Deep Survey detections in a 15 square degree portion of the survey shown in Galactic latitude vs. velocity wedge (blue circles) with 2MRS galaxies (black dots) and structures indicated from surveys above and below the plane (red circles and labels, Erdoğdu et al. 2006).

Detection from the ALFAZOA deep survey

Figure: HI spectrum showing a two-horned profile of one of our HI detections from the Deep survey, and the low noise (1 mJy) flat baselines we achieve.

ALFAZOA Data Release

* Publicly available data

Publications and Proceedings

* The ALFA ZOA Deep Survey: First Results. McIntyre, T. P., Henning, P. A., Minchin, R. F., Momjian, E., Butcher, Z., 2015, AJ, 150, 28.
ADS Bibcode: 2015AJ....150...28M.

* Discovery and Follow-up of a Nearby Galaxy from the Arecibo Zone of Avoidance Survey. McIntyre, T. P., Minchin, R. F., Henning, P. A., Kaur, A., & Parton, B., 2011, ApJL, 739, 26.
ADS Bibcode: 2011ApJ...739L..26M.

* The Arecibo L-band Feed Array Zone of Avoidance Survey I: Precursor Observations through the Inner and Outer Galaxy. Henning, P. A., Springob, C. M., Minchin, R. F., Momjian, E., Catinella, B., McIntyre, T., Day, F., Muller, E., Koribalski, B., Rosenberg, J. L., Schneider, S., Staveley-Smith, L., van Driel, W., 2010, AJ, 139, 2130.
ADS Bibcode: 2010AJ....139.2130H.

* The Arecibo Zone of Avoidance Survey: First Results. McIntyre, T. P., Minchin, R., & Henning, P., 2012, AAS meeting 210, #410.03 (McIntyre Dissertation Abstract).
ADS Bibcode: 2012AAS...21941003M.

* The ALFA Zone of Avoidance Survey: Results from the Precursor Observations. Springob C. M., Henning, P. A., Catinella, B., Day, F., Minchin, R., Momjian, E., Koribalski, B., Masters, K. L., Muller, E., Pantoja, C., Putman, M., Rosenberg, J. L, Schneider, S., Staveley-Smith, L., 2008, IAU Symp. 244.
ADS Bibcode: 2008IAUS..244..383S
Download PDF of the poster

* Abstracts from AAS posters:
January 2012 (Truebenbach et al.)
May 2011 (McIntyre et al.)
January 2011 (McIntyre et al.)
January 2008 (Lamm et al.)
January 2007 (Springob et al.)
June 2006 (Henning et al.)

The ALFA ZOA Team

Catinella, Barbara UWA
Butcher, Zhon UMass
Henning, Trish (PI) UNM
Koribalski, Baerbel ATNF
McIntyre, Travis UNM
Momjian, Emmanuel NRAO
Minchin, Robert NAIC
Putman, Mary Columbia U.
Rosenberg, Jessica GMU
Schneider, Stephen UMass
Springob, Christopher UWA
Staveley-Smith, Lister UWA
van Driel, Wim Paris Obs.
Viaz, Ensieh UWA

Useful links:

*Arecibo Astronomy pages
*E-ALFA pages
*Arecibo Legacy Fast ALFA (ALFALFA) survey project page
*Arecibo Ultra Deep Survey (AUDS) project page
*Arecibo Galaxy Environment Survey (AGES) project page
*Arecibo Observatory Telescope Schedule Database



Last updated: Monday, 05-Oct-2015 10:37:10 AST
R. Minchin