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Proposal Identification No.:

A2940 Arecibo Observatory

Date Received: 2014-Sep-01 14:26:23 William E. Gordon Telescope Observing Time Request COVER SHEET

Section I - General Information
Submitted for Sep 1 2014. This proposal has not been submitted before. Proposal Type: General Category: Sub-Category: Observation Category: Time Requested this semester: Hours already used for this pro ject: Additional Hours required to complete pro ject: Minimum Useful Time: Expected Data Storage: Prop osal Title: ABSTRACT: Regular Astronomy Spectroscopy Extragalactic 50 0 45m less than 100 GB

The gas mass of eleven damped Lyman-alpha systems at z<0.2

Despite 25 years of studies of damped Lyman-alpha absorbers (DLAs), the precursors of today's normal galaxies, the physical properties of the absorbers remain unknown. Low-redshift DLAs allow the exciting possibility of measuring the gas mass, size, and dynamical mass through HI-21cm emission studies, as well as their relations to the SFR, metallicity, etc. So far, this has only been possible for a single DLA, due to the lack of known low-z DLAs. We have searched the HST-COS archive to identify eleven DLAs at z<0.2, and propose here to use the Arecibo L-wide receiver to measure their gas masses via a search for redshifted HI-21cm emission. The observations have been planned so that even non-detections of HI emission will yield tight constraints on the HI mass, ruling out the possibility that the host galaxies are large spiral disks. We request 50 hours of time for this pro ject. Outreach Abstract: Damped Lyman-alpha absorbers (DLAs) are galaxies selected by their absorption signatures in quasar absorption spectra. Since they are selected by absorption, DLA samples are not biased towards bright galaxies, but contain typical galaxies at any redshift. Understanding the nature of DLAs has hence long been an focus of research in galaxy evolution. Unfortunately, almost no DLAs have direct estimates of basic quantities like their mass and size, as few DLAs were known at low redshifts, and the sensitivity of today's telescopes is not sufficient for measurements at significantly higher redshifts. The situation has changed with the new Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope, whose far-ultraviolet sensitivity has made it far easier to detect low-redshift DLAs. We have identified eleven DLAs at z<0.2 in a search of the HST-COS archive and propose to use the Arecibo telescope to measure their HI masses.

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Name Nissim Kanekar Tapasi Ghosh

Institution National Centre for Radio Astrophysics NAIC, Arecibo

E-mail nkanekar@ncra.tifr.res.in tghosh@naic.edu

Phone 912025719246 17878782612

Student no no

Additional Authors
(3) J. X. Prochaska (University of California, Santa Cruz; e-mail: xavier@ucolick.org) mneeleman@physics.ucsd.edu; Graduate student)

(4) Marcel Neeleman (University of California, San Diego; e-mail:

This work is not part of a thesis.

Remote Observing Request

X

Observer will travel to AO Remote Observing In Absentia (instructions to operator)

Section I I - Time Request
The following times are in LST. For these observations night-time is preferred.

Begin End IntervalInterval

Days Needed at This Interval

Time Constraints (Must Be Justified in the Prop osal Text) The proposal requests 4.5 hours of time on each of eleven sources which are at different RAs. The LST rise and set times are listed below. We request night-time scheduling as far as possible, to reduce the chance that the observations might be affected by RFI. Source LST-Rise LST-Set 2

J0951+3307 J1415+1634 J0930+2848 J1512+0128 J1241+2852 J1553+3548 J1619+3342 J1127+2654 J0154+0448 J1659+3735 J1435+3604

08:53:21 12:53:28 08:17:38 14:31:49 11:28:37 15:11:56 15:24:11 10:10:35 00:56:01 16:39:52 13:56:06

10:50:20 15:37:55 10:44:03 15:53:40 13:54:47 16:35:10 17:14:56 12:44:56 02:53:33 17:19:10 15:15:05

Section I I I - Instruments Needed
L-wide Atmospheric Observation Instruments:

Sp ecial Equipment or setup:

none

Section IV - RFI Considerations Frequency Ranges Planned
1180-1413

This proposal requires coordination with Punta Salinas radar within the band 1222-1381 MHz.. This proposal requires coordination with GPS L3 at 1381 MHz.

Section V - Observing List Target List
Ob ject RA Dec LST-Rise LST-Set J0951+3307 09:51:09.1 33:07:46 08:53:21 J1415+1634 14:15:42.9 16:34:14 12:53:28 J0930+2848 09:30:01.9 28:48:58 08:17:38 J1512+0128 15:12:37.1 01:28:46 14:31:49 J1241+2852 12:41:29.6 28:52:12 11:28:37 J1553+3548 15:53:04.9 35:48:29 15:11:56 J1619+3342 16:19:16.5 33:42:38 15:24:11 J1127+2654 11:27:36.4 26:54:51 10:10:35 J0154+0448 01:54:28.0 04:48:18 00:56:01 J1659+3735 16:59:31.9 37:35:29 16:39:52 J1435+3604 14:35:11.5 36:04:37 13:56:06

10:50:20 15:37:55 10:44:03 15:53:40 13:54:47 16:35:10 17:14:56 12:44:56 02:53:33 17:19:10 15:15:05

Details on redshifts and line frequencies are provided in a table with the scientific justification.

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