Observations - February, 2012
Abstracts
The Arecibo Galaxy Environments Survey (AGES) (A2048)
PI ò?? Dr. Jonathan I Davies, Cardiff University, UK
Proposal Date: January 27, 2006
Abstract: In this Extragalactic ALFA consortium proposal we are requesting 2000 hours of observing time over a 4 year period. The survey is specifically designed to investigate various galactic environments to higher sensitivity with better spatial, and velocity resolution than previous, fully sampled, 21cm multi-beam surveys. We have chosen specific objects in the nearby Universe upon which to centre our observations,Òš but will also use the full depth of the survey to quantify the HI properties of more distant galaxies. Our science goals include: the HI mass function in different environments, the contribution of neutral gas to the baryonic mass density, the nature of and link between high velocity hydrogen clouds and dwarf galaxies, the identification of gaseous tidal features as signatures of galaxy interactions and mergers, the low column density extent of galaxies, a comparison with atomic hydrogen detected by QSO absorption lines, the identification of isolated neutral gas clouds, the spatial distribution and properties of HI-selected galaxies and comparisons with numerical models of galaxy formation. Top
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The Alfa Ultra-Deep Survey: Deep HI Observations at 0<z<0.16 (A2133)
PI ò?? Dr. Wolfram Freudling, Space Telescope - European Coordinating Facility
Proposal Date: June 8, 2008
Abstract: The improved spatial and spectral survey capabilities available with ALFA opened a new era of high sensitivity observations for the Arecibo telescope. In a precursor experiment, we have demonstrated that it is possible to achieve noise of less than 50micro-Jy with integration times of about 40 hours per pointing, which translates into a HI mass sensitivity of a few 10E8 Msun at a redshift of about 0.16. We propose to use the new 200 MHz spectrometer available in late 2005 to carry out a blind HI survey with unprecedented sensitivity of 50micro-Jy for the redshift range of 0<z<0.16 over a total area of 0.36 square degrees. The ò??ALFA Ultra Deep Surveyò?? (AUDS) survey is more than an order of magnitude more sensitive than other HI surveys currently being carried out at Arecibo. The main scientific goals of the survey are to investigate the evolution of HI gas in the universe and explore the low-density gas around the edges of galaxies. The survey will be the deepest ò??blindò?? HI survey ever conducted. It will provide for the first time a direct link between HI absorption line measurements at high and intermediate redshifts and 21-cm emission line measurements at low redshifts. The expected number of HI detections at z>0.1 will be larger than that of all previous targeted and blind surveys combined. Top
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A Cm-wavelength Search for Prebiotic (and Other) Molecules in Arp 220-like Starburst Galaxies (A2334)
PI ò?? Dr. Christopher J Salter, NAIC
Co-PI ò?? Dr. Tapasi Ghosh
Proposal Date: June 1st, 2007
Abstract: Our on-going Arecibo line search (Project A2234) of the prototypical starburst/megamaser galaxy, Arp 220, has revealed a spectrum rich in molecular transitions. These include the ò??pre-bioticò?? molecules, methanimine (CH2NH) in emission, three v2=1 absorption lines of HCN, and possibly formic acid (HCOOH). In particular, the (rest) frequency range 4450-5300 MHz contains methanimine, formaldehyde, CH and formamide (NH2CHO) in emission, plus HCN (v2=1, J=4) and three lines of excited-OH in absorption. Our results mark the first distant extragalactic detection of methanimine, a molecule with high relevance to the origins of life. Further, the strong, but previously undetected, cm-wave HCN v2=1 direct l-type lines can aid the study of dense molecular gas and active star-forming regions in starburst galaxies. Consequently, we now propose observing the 4450-5300 MHz band towards 21 ò??Arp-220ò??-like galaxies, chosen such that emission and absorption lines of the strength found in Arp 220 would be clearly detected in them. Top
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GASS - The GALEX Arecibo SDSS Survey (A2335)
PI ò?? Dr. David Schiminovich, Columbia University
Co-PI ò?? Dr. Barbara Cantinella
Proposal Date: June 1st, 2007
Abstract: We propose the GALEX Arecibo SDSS Survey (GASS) a large targeted survey designed to measure the HI content of about 1000 galaxies at redshift 0.025<z<0.05 uniformly selected from the SDSS spectroscopic and GALEX imaging surveys to have stellar mass greater than 1e10 Msun. Our selected mass range straddles the recently identified ò??transition massò?? (3e10 Msun) above which galaxies show a marked decrease in their present to past-averaged star formation rates. GASS will produce the first statistically significant sample of massive ò??transitionò?? galaxies with homogeneously measured stellar masses, star formation rates and gas properties. By observing these galaxies down to a low gas mass fraction limit (1.5%), GASS will provide new insight into the physical mechanisms that shape the stellar mass function, regulate gas accretion and quench further galaxy growth by conversion of gas into stars. GASS will be of considerable legacy value not only in isolation but also by complementing on-going HI-selected surveys. Top
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Do the fundamental constants change with time? (A2525)
PI ò?? Dr. Nissim Kanekar, National Radio Astronomy Observatory
Co-PI ò?? Dr. Tapasi Ghosh
Proposal Date: September 30, 2009
Abstract: We propose to use the Arecibo L-band receiver to obtain deep, high resolution spectra in the redshifted 18cm satellite OH lines from the z = 0.247 source, PKS1413+135. The conjugate nature of the lines implies that these high-precision redshift measurements can be used to probe changes in the fine structure constant , the proton-electron mass ratio ÞÌ and the proton gyromagnetic ratio gp between z=0.247 and today. The sensitivity of the proposed observations to changes in and gp will be the highest from any astronomical technique and with the fewest systematics. The observations will directly confirm or deny the presence of a velocity offset between the satellite OH lines, tentatively detected (at 2.6 significance) in earlier Arecibo and WSRT spectra. If confirmed, this would be evidence for changes in , ÞÌ or gp, providing an avenue to probe new and fundamental physics. Our total time request is 160 hours, including all calibration. Top
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Are molecular clouds magnetically subcritical or supercritical overall? A survey of Zeeman observations of OH in absorption II. (A2600)
PI ò?? Dr. Kristen L Thompson, University of Kentucky
Co-PI ò?? Dr. Thomas Troland
Proposal Date: September 30, 2011
Abstract: Although much Zeeman work has been done to study the effect of magnetic fields on molecular cloud cores, very little is known about fields in the general envelopes of molecular clouds. Are molecular clouds as a whole magnetically subcritical or supercritical?Using Arecibo, Thompson and Troland have begun the first systematic observational survey to address this question using the Zeeman effect in OH absorption toward extra-galactic continuum sources that lie behind molecular clouds. In this first survey we have studied 7 lines-of-sight. However, the Zeeman effect can only reveal the line-of-sight magnetic field, which makes this study inherently statistical in nature. To obtain statistically meaningful results for this project, we require magnetic field information for more than 7 lines-of-sight. We have identified 26 additional extra-galactic sources. We will chose about 10 of these sources based upon a short survey of OH optical depths and conduct Zeeman observations, spending about 20 hours on each source. Top
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Surveying the Zone of Avoidance with ALFA: Outer Galaxy Region (A2611)
PI ò?? Dr. Patricia Henning, University of New Mexico
Co-PI ò?? Dr. Travis McIntyre
Proposal Date: December 10th, 2010
Abstract: We propose to survey the Zone of Avoidance (ZOA) deeply at 21-cm using the ALFA system, mapping hidden galaxies and large-scale structures at low Galactic latitudes. Mapping galaxies in the ZOA is one of four large blind surveys endorsed by the Extragalactic ALFA consortium, and is the only low-Galactic latitude project so endorsed. Our project A2152, to conduct deep observations commensally with PALFA, received an ò??Aò?? grade, and was to observe both the inner and outer Galaxy regions. We are proceeding commensally with PALFA (P2130) in the inner Galaxy region, and propose here that ZOA become primary project in the outer Galaxy region. We refer to our A2152 proposal for full scientific justification. Top
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A truly promising attempt to discover 6.7 GHz methanol masers outside the Local Group (A2622)
PI ò?? Dr. Andrea Tarchi, INAF - Osservatorio Astronomico di Cagliari
Co-PI ò?? Dr. Paola Castangia
Proposal Date: February 4th, 2011
Abstract: Taking profit of the large collecting area of the Arecibo telescope and the availability of the C-high receiver, we propose a very sensitive search for 6.7 GHz methanol masers in a promising sample of nearby galaxies outside the Local Group. The aim of this project is to detect strong Galactic-type CH3OH masers in the closest galaxies of the sample and to investigate the possible existence in any of the target galaxies of methanol kilomaser and megamaser sources, like those produced by H2O and OH. Any detection would constitute the first confident discovery of a methanol maser outside the Local Group and would open up the chance for interferometric follow-ups aimed at deriving proper motions and distances of galaxies. Top
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A search for radio emission from ultracool dwarfs (A2623)
PI ò?? Dr. Alexander Wolszczan, Penn State University
Co-PI ò?? Dr. Matthew Route
Proposal Date: February 4th, 2011
Abstract: We propose to continue our nearly completed pilot project (a2471) and use the Arecibo telescope with its C-band receiver and the Mock spectrometer to conduct a survey of ultracool dwarfs in search for a burst component of radio emission from these objects. The design of our search has been guided by the unexpected detection of gigahertz radio emission from several ultracool dwarfs, including our own recent first detection of polarized bursts from a T7 brown dwarf, J1047+21. The objectives of this project are to increase the number of detections of ultracool dwarfs to explore the mechanism of both the magnetic field and the radio emission generation in these objects. We are particularly excited about a possibility to explore the brown dwarf - massive planet boundary using magnetic fields as a diagnostic tool. A possibility to probe magnetic fields of the coolest, lowest-mass dwarfs may shed new light on the much debated transition from brown dwarfs to planets, the associated differences in structure, and the most proper way to distinguish between these two types of objects. Top
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HI Absorption Line Study Toward The Perseus Molecular Cloud (A2644)
PI ò?? Dr. Min-Young Lee, University of Wisconsin-Madison
Co-PI ò?? Dr. Snezana Stanimirovic
Proposal Date: June 3, 2011
Abstract: Recent analytical model for H2 formation in giant molecular clouds by Krumholz et al. (2009; KMT09) predicts that the minimum HI surface density = 6ò??10 solar mass/pc2 (at solar metallicity) is required for shielding H2 against photodissociation. We propose HI absorption measurements toward 19 radio continuum sources behind the Perseus molecular cloud to test KMT09ò??s prediction. Our preliminary estimate of the HI surface density using the GALFAò??HI emission data and under the assumption of optically thin HI gas shows that HI surface density is almost constant across Perseus with a value of 6ò??8 solar mass/pc2. However, the HI surface density may be underestimated due to the existence of high optical depth gas. With the proposed HI absorption and GALFAò??HI emission spectra we will derive the optical depth correction for the GALFAò??HI data for Perseus to test the KMT09ò??s prediction. Top
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Continuing the Monitoring of High Latitude OH/IR Stars (A2645)
PI ò?? Dr. Murray Lewis
Proposal Date: June 1st, 2011
Abstract: This is a proposal to continue the monitoring of OH masers in high latitude OH/IR stars. It is only ever accorded scraps of time, most in the daytime / twilight gaps of the telescope schedule. Nevertheless, it has resulted in a number of discoveries, including the identification of both ò??deadò?? OH/IR stars, stars with revived masers, and a star that has changed from a classic double-peaked to single-peaked spectrum, among others. The proposal seeks to continue this fruitful study, in part by filling in gaps in pulsation-phase coverage that result from the episodic (rather than regular) availability of time. There are two institutional byproducts: (i) more telescope hours are used gainfully, and (ii) OH observations are continued in the 1612 MHz band adjacent to the Iridium satellite band, which helps to maintain the record of this bandò??s importance to astronomers. Top
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Pilot Observations for a Drift-Scan Pulsar Search at 327 Mhz (P1693)
PI ò?? Dr. Paulo C. Freire, NAIC
Co-PI ò?? Dr. James Cordes
Proposal Date: June 1st, 2002
Abstract: We request 100hr of telescope time to conduct a pilot drift-scan pulsar search using the new 327 MHz Gregorian receiver and the Wideband Arecibo Pulsar Processor (WAPP). Using a 30-MHz band expected to be available from the new receiver, we will be twice as sensitive to nearby low-DM pulsars as the present 430-MHz drift-scan surveys for pulsars with average spectral indices. The number detectable at 327 MHz should increase by at least a factor of 2. If these expectations are confirmed, we intent to propose a more ambitious all-sky 327-MHz drift-scan survey, which would complement future ALFA (Arecibo L-Band Feed Array) pulsar surveys that would favor pulsars with flatter spectra. Top
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An ALFA Pulsar Survey of the Galactic Plane (P2030)
PI ò?? Dr. James Cordes, Cornell University
Co-PI ò?? Dr. Fernando Camilo
Proposal Date: October 1st, 2004
Abstract: We propose the first year of a large-scale survey of the Galactic plane using ALFA. Primary emphasis will be on the inner Galaxy but we also propose a search of the Galactic anticenter region. Areciboò??s high gain and wide-band spectrometers allow surveys of much greater volumes (per unit solid angle) than the eminently successful Parkes Multibeam Survey, particularly for short-period pulsars. The survey will thus find not only a large sample of pulsars, but also rare objects that are especially useful for probing fundamental aspects of neutron stars, testing theories of gravity, and detecting gravitational backgrounds, among other enterprises. We estimate that with our eventual software processing, we will discover a pulsar about every 1.5 hr of on-sky observing time. In addition, our analysis also will detect transient signals from pulsars that are intermittent or from other kinds of objects. Preliminary observations in 2004 Aug-Sep have yielded discovery of eight new pulsars in a quick-look analysis, including one from detection of its single pulses. Many more are expected in the data we already have. Given the pace of observations so far, our ability to glean from them new pulsar discoveries, and our expectation that full resolution code will complete the processing of precursor-survey data by the end of 2005 January, a comprehensive pulsar survey using existing WAPP spectrometers can be initiated on or after 2005 Feb 1. Top
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Expansion of the NANOGrav Pulsar Timing Array (P2554)
PI ò?? Dr. Paulo C Freire, Max-Planck-Institut fur Radioastronomie
Proposal Date: February 11, 2010
Abstract: Timing 3 new millisecond pulsars found in previously unidentified Fermi sources. Apart from assisting with finding the timing solutions and detect the gamma-ray pulsations, we want to check the timing precision of these pulsars with Arecibo. Preliminary indications are that at least two of these pulsars might be suitable for inclusion in the pulsar timing array now being used to attempt to detect very low-frequency gravitational waves. Top
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Expansion of the NANOGrav Pulsar Timing Array (P2624)
PI ò?? Dr. Paul B. Demorest, NRAO
Co-PI ò?? Dr. David J. Nice
Proposal Date: February 4, 2011
Abstract: Direct detection of grav