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Title: THE ALFALFA H I ABSORPTION PILOT SURVEY: A WIDE-AREA BLIND DAMPED Ly{alpha} SYSTEM SURVEY OF THE LOCAL UNIVERSE

Abstract

We present the results of a pilot survey for neutral hydrogen (H I) 21 cm absorption in the Arecibo Legacy Fast Arecibo L-Band Feed Array (ALFALFA) Survey. This project is a wide-area 'blind' search for H I absorption in the local universe, spanning -650 km s{sup -1} < cz < 17, 500 km s{sup -1} and covering 517.0 deg{sup 2} (7% of the full ALFALFA survey). The survey is sensitive to H I absorption lines stronger than 7.7 mJy (8983 radio sources) and is 90% complete for lines stronger than 11.0 mJy (7296 sources). The total redshift interval sensitive to all damped Ly{alpha} (DLA) systems (N{sub H{sub i}}{>=}2 Multiplication-Sign 10{sup 20} cm{sup -2}) is {Delta}z = 7.0 (129 objects, assuming T{sub s} = 100 K and covering fraction unity); for super-DLAs (N{sub H{sub i}}{>=}2 Multiplication-Sign 10{sup 21} cm{sup -2}) it is {Delta}z = 128.2 (2353 objects). We re-detect the intrinsic H I absorption line in UGC 6081 but detect no intervening absorption line systems. We compute a 95% confidence upper limit on the column density frequency distribution function f(N{sub H{sub i}},X) spanning four orders of magnitude in column density, 10{sup 19} (T{sub s} /100 K) (1/f) cm{sup -2}<N{sub H{sub I}}<10{supmore » 23}(Ts/100 K)(1/f) cm{sup -2}, that is consistent with previous redshifted optical DLA surveys and the aggregate H I 21 cm emission in the local universe. The detection rate is in agreement with extant observations. This pilot survey suggests that an absorption line search of the complete ALFALFA survey-or any higher redshift, larger bandwidth, or more sensitive survey, such as those planned for Square Kilometer Array pathfinders or a low-frequency lunar array-will either make numerous detections or will set a strong statistical lower limit on the typical spin temperature of neutral hydrogen gas.« less

Authors:
;  [1]; ;  [2]
  1. Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, 389 UCB, Boulder, CO 80309-0389 (United States)
  2. Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States)
Publication Date:
OSTI Identifier:
21612633
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 742; Journal Issue: 1; Other Information: DOI: 10.1088/0004-637X/742/1/60; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; DENSITY; DISTRIBUTION FUNCTIONS; GALAXIES; QUASARS; RED SHIFT; UNIVERSE; COSMIC RADIO SOURCES; FUNCTIONS; PHYSICAL PROPERTIES; SORPTION

Citation Formats

Darling, Jeremy, Macdonald, Erin P., Haynes, Martha P., and Giovanelli, Riccardo, E-mail: jdarling@colorado.edu, E-mail: e.macdonald@physics.gla.ac.uk, E-mail: haynes@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu. THE ALFALFA H I ABSORPTION PILOT SURVEY: A WIDE-AREA BLIND DAMPED Ly{alpha} SYSTEM SURVEY OF THE LOCAL UNIVERSE. United States: N. p., 2011. Web. doi:10.1088/0004-637X/742/1/60; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Darling, Jeremy, Macdonald, Erin P., Haynes, Martha P., & Giovanelli, Riccardo, E-mail: jdarling@colorado.edu, E-mail: e.macdonald@physics.gla.ac.uk, E-mail: haynes@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu. THE ALFALFA H I ABSORPTION PILOT SURVEY: A WIDE-AREA BLIND DAMPED Ly{alpha} SYSTEM SURVEY OF THE LOCAL UNIVERSE. United States. doi:10.1088/0004-637X/742/1/60; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Darling, Jeremy, Macdonald, Erin P., Haynes, Martha P., and Giovanelli, Riccardo, E-mail: jdarling@colorado.edu, E-mail: e.macdonald@physics.gla.ac.uk, E-mail: haynes@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu. Sun . "THE ALFALFA H I ABSORPTION PILOT SURVEY: A WIDE-AREA BLIND DAMPED Ly{alpha} SYSTEM SURVEY OF THE LOCAL UNIVERSE". United States. doi:10.1088/0004-637X/742/1/60; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21612633,
title = {THE ALFALFA H I ABSORPTION PILOT SURVEY: A WIDE-AREA BLIND DAMPED Ly{alpha} SYSTEM SURVEY OF THE LOCAL UNIVERSE},
author = {Darling, Jeremy and Macdonald, Erin P. and Haynes, Martha P. and Giovanelli, Riccardo, E-mail: jdarling@colorado.edu, E-mail: e.macdonald@physics.gla.ac.uk, E-mail: haynes@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu},
abstractNote = {We present the results of a pilot survey for neutral hydrogen (H I) 21 cm absorption in the Arecibo Legacy Fast Arecibo L-Band Feed Array (ALFALFA) Survey. This project is a wide-area 'blind' search for H I absorption in the local universe, spanning -650 km s{sup -1} < cz < 17, 500 km s{sup -1} and covering 517.0 deg{sup 2} (7% of the full ALFALFA survey). The survey is sensitive to H I absorption lines stronger than 7.7 mJy (8983 radio sources) and is 90% complete for lines stronger than 11.0 mJy (7296 sources). The total redshift interval sensitive to all damped Ly{alpha} (DLA) systems (N{sub H{sub i}}{>=}2 Multiplication-Sign 10{sup 20} cm{sup -2}) is {Delta}z = 7.0 (129 objects, assuming T{sub s} = 100 K and covering fraction unity); for super-DLAs (N{sub H{sub i}}{>=}2 Multiplication-Sign 10{sup 21} cm{sup -2}) it is {Delta}z = 128.2 (2353 objects). We re-detect the intrinsic H I absorption line in UGC 6081 but detect no intervening absorption line systems. We compute a 95% confidence upper limit on the column density frequency distribution function f(N{sub H{sub i}},X) spanning four orders of magnitude in column density, 10{sup 19} (T{sub s} /100 K) (1/f) cm{sup -2}<N{sub H{sub I}}<10{sup 23}(Ts/100 K)(1/f) cm{sup -2}, that is consistent with previous redshifted optical DLA surveys and the aggregate H I 21 cm emission in the local universe. The detection rate is in agreement with extant observations. This pilot survey suggests that an absorption line search of the complete ALFALFA survey-or any higher redshift, larger bandwidth, or more sensitive survey, such as those planned for Square Kilometer Array pathfinders or a low-frequency lunar array-will either make numerous detections or will set a strong statistical lower limit on the typical spin temperature of neutral hydrogen gas.},
doi = {10.1088/0004-637X/742/1/60; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
journal = {Astrophysical Journal},
number = 1,
volume = 742,
place = {United States},
year = {Sun Nov 20 00:00:00 EST 2011},
month = {Sun Nov 20 00:00:00 EST 2011}
}