naic/nrao single-dish summer school, july 2011 a potpourri of arecibo single-dish highlights chris...

NAIC/NRAO Single-Dish Summer School, July 2011

A Potpourri of Arecibo A Potpourri of Arecibo Single-Dish Highlights Single-Dish Highlights

Chris Salter Chris Salter

Arecibo Observatory (National Astronomy & Ionosphere Center)


Arecibo Astronomy Observing DetailsArecibo Astronomy Observing Details

-- 57% of passive astronomy telescope time for large (≥300 hr) survey projects:

all currently using ALFA or LBW receivers.

-- 43% of passive astronomy telescope time for other single-dish and VLBI studies.

-- Frequency coverage: 327, 430 & 800 MHz, 1.1-10 GHz via 6 receivers + ALFA.


ReceiversReceivers

800


PALFA -- Search for Low-b Pulsars

• PSR Period = 2.15 ms

• Binary Period = 95 day with 1MO main-seq. companion.

• Orbital Eccentricity = 0.44

• PSR mass = 1.667±0.021Mo → implications for EOS of cold ultra-dense matter.

J1903+0327

• Since 2009 has recorded 300-MHz bandwidth.

• So far, 170 PSRs detected; 54 are new.

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

• Seven msec PSRs discovered → PTA.

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

• PSR J1906+0746 shows secular pulsar-shape evolution due to geodetic precession.

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

• Data processing in part via Einstein@Home involving ~100k clients worldwide.


Hankins & Eilek find giant Crab PSR interpulses to differ in both time and frequency from giant main pulses! The main pulses can be resolved into brief nanoshots (see below) of “modest” fractional bandwidth, believed due to soliton collapse in strong plasma turbulence. However, unlike predictions if the pulses come from opposing magnetic poles, the giant main and interpulses are extremely different.

A 2 106 Jy main pulse from the Crab pulsar showing “nanoshots”. These are unresolved with 0.4-ns resolution at 9.2 GHz. For the light-travel size (~12 cm), Tb~2 1041 K (a record!)

Giant Pulses from the Crab Giant Pulses from the Crab PulsarPulsar

(Courtesy: Tim Hankins)


Main Pulse:Main Pulse: Typically, several bursts of < 1 sec per pulse, with width -2.Occasional ≤1-ns “nanoshots”.Weakly polarized.More infrequent than interpulse, but more intense.

9.2 GHz

Interpulse:Interpulse:Emission bands in dynamic spectrum.Structure of a few sec duration.Bands seen in every interpulse,

but never in the main pulse.Band spacing of /~0.06.Interpulse has slightly higher DM than

main pulse (0.05%).Strongly linearly polarized.

No existing model can explain the banded interpulse structure.


Apparent > Apparent > cc Wave Propagation in the ISM Wave Propagation in the ISM

The group velocity of the ISM is > c near the HI resonance line due to “anomalous dispersion”.

The plot above shows the expected absorption and delay spectra after propagation through a cloud of HI in the ISM with T

S= 100 K, τ = 1.

HI Emission Spectrum

PSR Absorption Spectrum

PSR Delay Spectrum

Delay Spectra for 3 Consecutive Days

Potential tool for studying the HI properties of the ISM. (Note: It does NOT violate Special Relativity!)

(Courtesy: Rick Jenet)


Pulsar Study: The “Planets Pulsar”

Alex Wolszczan is completing a 17-yr study of the “planets pulsar”, PSR B1257+12. His timing fits includes;

• All PSR parameters

• Astrometric parameters

• Three planets (including the mutual perturbations of Planets b & c)

•DM variations (3rd panel).

Highlights of 17-yr Study of B1257+12

• First exoplanets.

• First detection of planets in mean motion resonance (MMR 3:2).

• First multiplanet system.

• First terrestrial-mass system.

• First dynamical analog of the inner solar system (scaled down by a factor of ~2).

430-MHz Raw Residuals

1400-MHz Raw Residuals

Residuals including DM Variations

Dispersion Measure (DM) Variations

(Courtesy: Alex Wolczszan)


GALFACTS (GALFA Continuum Transit Survey)GALFACTS (GALFA Continuum Transit Survey) • Full-Stokes, all-Arecibo-sky, continuum

survey.

• Employs meridian NODding scans with subsequent “multi-beam” basket-weaving to optimize zero-levels.

• Use of an original multi-beam CLEAN.

• Bandwidth = 300 MHz → Faraday tomography, Ip(x, y, RM).

• Full GALFACTS survey began on November 13, 2008.

• As of July 11, approaching 50% complete.

• Catalog of Poln. Percentage, Position Angle & RM for 50,000 sources.

• Studies of the Galactic Magnetic Field.

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

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

• Studies of high-b Galactic Loops.

• Foreground removal for the Planck full-Stokes CMB study.

• GALFA-TOG2 HI commensal project.


GALFACTS TECHNIQUESGALFACTS TECHNIQUES

Stokes I Dirty Image

Multi-beam Clean Image (HPBW=3.5')

NVSS Comparison(HPBW=0.7')

ALFA beams

Tracks after several passes

These are “woven” together to optimize zerolevels.


Effelsberg Survey Image on N1


GALFACTS


Stokes IStokes I

Stokes U

Stokes Q

GALFACTS – FULL STOKESGALFACTS – FULL STOKES

WHY GALFA-HI?WHY GALFA-HI?

With single-dish brightness temperature sensitivity and high spectral and angular resolution, it covers new parameter space:


I-GALFA I-GALFA – The Inner Galaxy ALFA low-– The Inner Galaxy ALFA low-bb HI Survey HI Survey

• I-GALFA covers 35°≤ l ≤85°, |b| ≤10°.

• Observations were completed in September 2009.

• HPBW=3.35', Trms

= 0.25 K, Δv

chan = 0.18 km/s, |v

lsr| < 750 km/s.

• (Triple) Commensal with ZOA & GALFACTS2.

•Prominent is the HI/continuum supershell GS 041+01+27, probably lying in the Sagittarius spiral arm.

(top) I-GALFA HI image – vlsr

= +27 km/s; (bottom) GALFACTS2 L-band continuum image

Disc-Halo Interface


GALFA-HI Pointing Record as of 2008 March 14

GALSPECT has 8192 channels over 7.14 MHz → 0.18 km/s/channel, and ± 750 km/s total coverage

GALFA-H I TOGS/TOGS2 ObservationsGALFA-H I TOGS/TOGS2 Observations

GALFA-HI Pointing Record as of 2009 February 26

GALFA-HI Pointing Record as of 2010 April 4


• TOGS/TOGS2 is commensal with GALFACTS, ALFALFA & AGES, mapping the whole Arecibo sky in HI at no overhead in observing time.

• Used to study, (a) Galactic structure, (b) correlation of HVC HI and dust contents, (c) HI clouds surrounding M33 attributed to M33–M31 tidal interactions, (d) HI content of Local Group dwarf galaxies, and (e) HI content of globular clusters.

GALFA-TOGS/TOGS2 Wide-Area HI SurveyGALFA-TOGS/TOGS2 Wide-Area HI Survey

TOGS = “Turn On GALFA Spectrometer!”

HI for -2 km/ s

HI for +18 km/ s


Red Dwarf “Pulsars”Red Dwarf “Pulsars”

• A number of ultra-cool dwarf stars have been observed at Arecibo displaying similarities between the pulses measured. Examples of

(left) TVLM 513-46546 and (right) 2MASSW J0746425+200032 in Stokes-V.

• Pulses have brightness temperature > 1015 K. For electron cyclotron maser emission, magnetic field strengths of ~1650 Gauss are implied.

• Simultaneous Arecibo, Hα, optical photometry, and NIR spectrophometry of TVLM 513, show in-phase variations for radio, Hα, [OI] and the optical continuum.

(Courtesy: Greg Hallinan)


HI Forbidden-Velocity WingsHI Forbidden-Velocity Wings

LDS

b=−0.5°

HVC 004-6: •Arecibo (LBW and ALFA) + GBT observations of 22 FVWs.

• 12-13 show shell-type structure; “missing” SNRs?

• 9-10 show cloud-type structure; halo clouds or HVCs?

FVW's 173.0+3.0 & 173.0+0.0: Red = +45 – +35 km/s, Green = +35 – +25 km/s, Blue = +25 – +15 km/s. The HI emission coincides with a weak continuum shell.

FVW G39.0+4.0: Red = +110 – +135 km/s, Green = +95 – 110 km/s, Blue = +80 – +95 km/s. Stars = Early-type stars in field; Triangles = Pulsars

(Courtesy: Ji-hyun Kang)


HI Absorption at HI Absorption at zz ~ 0.9 ~ 0.9

HI absorption in the host galaxy HI absorption in the host galaxy of CTA 21 against the of CTA 21 against the continuum emission of the continuum emission of the central quasarcentral quasar

Observed at Arecibo on 20 & Observed at Arecibo on 20 & 21 September 200921 September 2009 Redshift,Redshift, z z = 0.906 = 0.906 Distance = 5866 MpcDistance = 5866 Mpc CTA 21 is seen at 46% of the CTA 21 is seen at 46% of the present age of the Universe present age of the Universe

Central Frequency = 745.5 MHz

Analog-to-Digital migration of TV transmissions in June 2009 temporarily freed up the 700–800 MHz band. Arecibo has provided and commissioned a receiver.

HI absorption in the host galaxy HI absorption in the host galaxy of 4C+15.05 against the of 4C+15.05 against the continuum emission of the continuum emission of the central quasarcentral quasar

Observed at Arecibo on 3, 4 & Observed at Arecibo on 3, 4 & 5 October 20105 October 2010 Redshift,Redshift, z z = 0.833 = 0.833 Distance = 5283 MpcDistance = 5283 Mpc Resolves optical disagreement Resolves optical disagreement between between zz=0.405 and 0.833 =0.405 and 0.833

Central Frequency = 780.4 MHz


A Spectral Scan of Arp 220:1.1 – 10 GHz

Arp 220 is a star-burst galaxy at a distance of 78 Mpc.

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

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

(HST:Optical)

(VLA:Radio Wavlength 6cm)


The Spectrum of Arp 220 – Prebiotic Molecules

Methanimine (CH2NH) observed for the

first time outside of the Milky Way (where it has only been observed in one source!) This is probably a maser emitter.

“Bending” (v2=1) transitions of HCN detected for the very first time in the radio region.These lines are at L-, C-, C-Hi & X-band.

Recent News: Detection of v2=1, J=3, HCN in Arp 220 (2645 MHz) gives a line-center optical depth, ~ 3 at 1630 MHz.


The Spectrum of Arp 220 – OH & Other Lines

OH Absorption (6 cm)



18OH or Formic Acid? (18 cm) CH emission triplet (λ9 cm)

Co-added Hydrogen Recombination Lines (H119α → H127α). Peak Intensity ≈ 600 μJy/beam; rms noise ≈ 50 μJy/beam.

HH22CO at 4830 MHzCO at 4830 MHz

OH at 4660 MHzOH at 4660 MHz



HCN at 4488 MHzHCN at 4488 MHz

CHCH22NH at 5290 MHzNH at 5290 MHz

Arecibo Spectra for Zw 049.057Arecibo Spectra for Zw 049.057

Is Arp 220 Unique?Is Arp 220 Unique?


Zeeman Effect in ULIRG Megamasers

• Many OH megamasers (OHMs) in ULIRGs show Zeeman splitting of individual components yielding typical line-of-sight magnetic fields of 0.3-18 mGauss.

• Following-up their initial detection of this phenomenon for ULIRGS, the P.I.’s are now making a Zeeman survey of all suitable ULIRG OHMs in the Arecibo sky.

• Linear polarization of the OHM in Arp 220 yields a Rotation Measure.

•To resolve the Zeeman components spatially, VLBI has been made using the HSA (including Arecibo) allowing investigation of the origins of the magnetic fields.

(PI’s: Tim Robishaw & Carl Heiles)


Arecibo helps Protect the Earth againstArecibo helps Protect the Earth against Space Invaders!!!!Space Invaders!!!!

Asteroid 2001 Asteroid 2001 SN263 and its SN263 and its two moonlets.two moonlets.

Asteroid Hermes Asteroid Hermes that was lost for that was lost for 66 years.66 years.

Asteroid 1999 JM8 Asteroid 1999 JM8 about 2 miles in about 2 miles in diameter.diameter.

65 million years ago? 65 million years ago?

AD 1908: Tunguska, Siberia AD 1908: Tunguska, Siberia

(Artist's(Artist'sImpression)Impression)

(Reality)(Reality)

Sizes & shape Rotation rates If there are moonlets Orbits

For near-Earth asteroids, the Arecibo radar measures;


Muchas Muchas GraciasGracias


The Three Little PigsThe Three Little Pigs(PI: Josh Goldston Peek)

• Tiny clouds found at b ≈ 85°; Δθ ≈ 1'.

• VLA follow-up shows condensed cores , optically-thick, with TB ≈ 10K.

• Arecibo measures Magnetic Field strength ~14 μG → 200 – 800 times the magnetic pressure of the WIM.

• Upper limits on OH emission from Arecibo.

Now Pigs by the Drove!Now Pigs by the Drove!(Ayesha Begum & Snezana Stanimirovic)

•About 100 compact, cold clouds, isolated from Galactic emission in a limited area of the TOGS/TOGS2 survey.

• Median angular size ~5', Tb ~ 0.7 K, FWHM ~ 4.2 km/s,

and NHI

~ 5 × 1018 cm-2.

• Clouds deviate from Galactic rotation by 10 – 40 km/s, and evidence for multiphase medium and velocity gradients.

naic/nrao single-dish summer school, july 2011 a potpourri of arecibo single-dish highlights chris...

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