radio astronomy at arecibo

NAIC’s 2009 Program Plan & Budget PresentationOctober 2008

RADIO ASTRONOMY AT ARECIBO

Chris Salter (for Murray Lewis)


Arecibo Astronomy Observing Parameters

-- 80% of astronomy telescope time for large (≥300 hr) survey projects:

currently all using ALFA or LBW receivers.

-- 20% of astronomy telescope time for other astronomy projects.

-- Frequency coverage: 327 & 430 MHz, 1.1-10 GHz via 6 receivers + ALFA.


ALFA: The Arecibo L-band Feed Array

• Installed Apr 2004, surveys initiated Feb 2005

• 7 beams × 2 poln (linear) = 14 pixels

• Bandwidth = 1225-1525 MHz

• Unmatched sensitivity: SEFD = ≈3 Jy

• HPBW=3.3′ × 3.8′ on 11′ × 13′ ellipse

• Commensal operations for sky surveys

•ALFA consortia self-organized by community


Current Arecibo Survey Projects

• Pulsar Search: PALFA Survey, commensal with ZoA & RRL.

• Galactic λ21-cm HI: Individual-area GALFA Surveys; I-GALFA commensal with GALFACTS & ZoA.

• Extragalactic λ21-cm HI: ALFALFA, AGES, AUDS, commensal with GALFA-TOGS.

• Continuum: GALFACTS (Full-Stokes), commensal with GALFA-TOGS2 & ZoA.

• Single-Pixel Surveys: (a) Zeeman-effect survey of magnetic fields in ULIRGS, (b) GASS (GALEX Arecibo SDSS Survey) survey of HI in 1000 massive galaxies.


PALFA -- Search for Low-b Pulsars

• PSR Period = 2.15 ms

• Binary Period = 95 day

• Orbital Eccentricity = 0.44

• PSR mass = 1.68±0.01Mo → implications for EOS of cold ultra-dense matter.

J1903+0327

• Until now, using 100-MHz bandwidth with the WAPP spectrometer.

• From 2009 will migrate to the Mock spectrometer giving 300-MHz bandwidth.

• So far, 162 PSRs detected; 46 are new.

• Some PSRs detected via periodicity analysis, some by strong single pulses.

• Three high-DM, msec PSRs discovered.

• Vela-like PSR likely associated with a TeV γ-ray source.

• Eight sporadic pulsars/Rotating RAdio Transients (RRATs).


Pulsar Timing Array: Gravitational Wave Search

• Now investigating astrophysically interesting parameter space.

• Requires well-distributed array of highly-stable pulsars.

• Negligible cost compared with LIGO and LISA.


Red = Optical only; Blue = HI only; Green = both.

07:30 < RA < 16:30 & 08° < Dec < 16°5670 galaxies with cz < 8000 km/s

ALFALFA – Arecibo Legacy Fast ALFA Survey • Will cover 7000 deg2. 0o<Dec<+36o, 22h<RA<3h & 7.5h<RA<16.5h.

• 8×sensitivity, 4×angular resolution, 3×spectral resolution, 1.6×velocity coverage of HIPASS.

• 59% of requested time received.

• Large part of Virgo cluster complete to 2×107 Mo.

• Cataloging HVCs of Milky Way & M33.

•Undergraduate-ALFALFA “Groups of Galaxies” project.

• Continuous increase in number of ALFALFA-based projects.

• Leo & Virgo regions of Local Supercluster at cz<2000 kms-1, “Great Wall” at cz>6000 kms-1.

• In Perseus-Pisces Void, not one galaxy detected wih HI where 38 are expected!


Parkes HIPASS survey: Zwaan et al. 2003

?

• Previous surveys have detected few (if any) objects with low HI.

• At low mass end, HIMF estimates differ by > factor of 10 : Rosenberg & Schneider (2000) versus Zwaan et al. (1997)

ALFALFA & AGES: HI Census → HI Mass Function

• ALFALFA makes ≈8000 detections in an area where HIPASS detected 290!

• Large number of detections of galaxies with MHI < 108 Mo.


HI emission from Disk Galaxies at z~0.2• Sample from SDSS based on 0.16<z<0.27, Hα emission line strength, inclination >45o,

disk morphology, and relative isolation.

• 41 galaxies targeted with L–band wide, yielding 26 detections + 8 tentative ones with HI masses of 3 − 8 × 1010 Mּס.

• ON-source integration time 1 − 4 hr per object.


GALFA-HI: The Tip of the Magellanic Stream (MS)

• Four large-scale HI streams extending over 20o, with different morphologies and velocity gradients.

• Extensive population of clouds (Δθ≈3.5′−10′) likely due to thermal instabilities as MS trails through the Galactic Halo

• The above supports a tidal model for the MS.

• The observations suggest a distance to the tip of the MS≈70 kpc.


• TOGS/TOGS2 map large areas of sky in HI at no overhead in observing time. • Used to study, (a) correlation of HI and dust content of HVCs, (b) HI clouds surrounding M33 attributed to tidal interaction of M33 with M31, (c) HI content of Local Group dwarf galaxies, (d) HI shell around a nearby molecular cloud complex, and (e) HI content of globular clusters.

GALFA-TOGS HI Wide-Area Survey(Commensal with ALFALFA & AGES)

TOGS = “Turn On GALFA Spectrometer!”


GALFACTS (GALFA Continuum Transit

Survey) • Full-Stokes, all-Arecibo-sky, continuum

survey.• Use of original multi-beam CLEAN.• Bandwidth = 300 MHz → Faraday

tomography, Ip(x, y, RM).• Catalog Poln. Percentage, Position

Angle & RM of 50,000 sources → Galactic Magnetic Field Studies.

• Thermal-nonthermal separation of low-b Galactic continuum emission.

• Studies of discrete Galactic radio sources (e.g. SNRs & HII regions).

• Studies of the Galactic Loops.• Foreground removal for Planck full-

Stokes CMB study.• GALFA-TOG2 HI commensal project. • Calibration run in Oct 2008 was first

scheduled observations with Mock spectrometers. Full GALFACTS survey begins November 2008.

(GALFACTS pilot study of Perseus Molecular Cloud region)


Red Dwarf “Pulsars” – TVLM 513

• Arecibo provides the wide bandwidth and high spectral resolution not available with the VLA → dynamic spectra of the pulses from TVLM 513.

• Pulses resolved in both time and frequency → Brightness temperature > 1015 K for this electron cyclotron maser emission.

• Radio emission occurs at electron cyclotron frequency → magnetic field strength of kiloGauss.

• HSA (including Arecibo) used for VLBI follow-up observations.


Spectral Scan of Arp 220: 1.1 – 10 GHz

(HST:Optical)

(VLA:Radio λ 6cm)

• Arp 220 is an Ultra-luminous Infra-Red Galaxy (ULIRG) galaxy at a distance of 78 Mpc.

• It is the result of a collision between 2 galaxies now in the final stages of merging.

• It is forming stars at 100 times the rate of the Milky Way.


Line detections in IC 860: (Top) HCN v2=1, J=4 and excited-OH (4660 MHz) absorption lines: (Bottom) H2CO and CH2NH emission lines,

Pre-biotic Molecules and Other Lines in ULIRGs(a) Arp 220 (b) Other ULIRGs

v2=1 direct l-type absorption lines of HCN (J = 4, 5 and 6). An excitation temperature of ~135 K is implied. Non-detection of the J=2 level is likely to be due is to free-free absorption in the foreground ionized ISM.

Emission from the 110–111 methanimine (CH2NH) multiplet, likely to represent weak maser emission.

Latest News: Detection of v2=1, J=3, HCN in Arp 220 (2645 MHz) gives a line-center optical depth, ~ 3 at 1630 MHz. Also CH triplet (3.3 GHz), λ4-cm absorption lines of OH and hydrogen recombination lines down to 3 GHz.

IC 860

H109α recombination line in NGC 3628


Arecibo VLBI Highlights -- 2008

+ + +

• Continued High Sensitivity Array (HSA) operations.

• Continued EVN and Global Array operations

• Ultra-wideband VLBI with GBT at 4 Gbit/sec data rate.

• Successful eVLBI operations at 512 Mbit/sec.

• Participation in first four-continent eVLBI array.

http://www.naic.edu/


eVLBI at 512-Mbit/sec

• First trans-atlantic eVLBI fringes at a data rate of 512 Mbits/sec.


Ultra-Wideband VLBI (UVLBI)

• The ultra-sensitive Arecibo-GBT baseline was used to search for the anticipated weak central images in 8 gravitational-lens systems.

• 2 × Mk5B VLBI recorders and a digital backend were loaned by Haystack Observatory allowing 4-Gbit/sec data rates.

• In a 10-sec integration on the Ar-Gb baseline, a signal-to-noise ratio of 1700:1 was achieved on a 122 mJy compact source.

• The noise level is 230/√T(sec) μJy/beam.

• This is the “most sensitive radio interferometry in history!”


Expected Developments over 2008-9

• Mock spectrometer availability will enable a number of ALFA projects to begin or upgrade capabilities (GALFACTS/TOGS2, RRL, AUDS, PALFA, Z0A).

• Development of a Mock spectrometer “single-pixel” option will allow a 1-GHz bandwidth with 0.15 km/s velocity resolution at 10 GHz, leading to consortium proposal for spectral survey of Galactic molecular-line sources.

• VLBI equipment upgrade to a digital backend and Mk5B/C recorder/s will allow regular recording at 2-4 times the present data rate of 1 Gbits/sec.

• Exploitation of 512-Mbit/sec eVLBI for regular science runs (e.g. ToO, rapid response science). Also removes the complications of disc recording.

• Design study for a 40-beam focal-plane phased feed array can give an HI mapping array with the observing speed of ASKAP or MeerKAT.

• PALFA expecting to begin commensal high-b survey to find well distributed, very stable, msec PSRs for gravitational-wave PTA.

radio astronomy at arecibo

Documents

low hi

hi emission

correlation of hi

b hi clouds

d hi shell

largescale hi streams

e hi content of globular

palfa survey