Long Wavelength Array

Exploring the Transient Universe Exploring the Transient Universe with the Long Wavelength Arraywith the Long Wavelength Array

(LWA:(LWA: http://lwa.nrl.navy.mil)

Greg Taylor (KIPAC / NRAO / UNM)

for the Southwest Consortium (UNM, NRL, UT, LANL)

Wavelengths longer than 3 meters“Long Wavelengths” (LW) Frequencies below 90 MHz

Long Wavelength Array

The 2004 Dec. 27 Giant FlareThe 2004 Dec. 27 Giant Flare

Swift was ~ 5o from the sun

It’s distance ≈ 15 kpc

Eiso ~ (2-9)1046 erg

Eiso,spike / Eiso,tail ~ 300

Expanding radio afterglow

(Palmer et al. 2005)

Long Wavelength Array

From Cameron et al. 2005

Radio Afterglow has a Steep Spectrum ~ -0.6 at t+7 days down to at least 220 MHz

Flux > 1 Jy at early times and low frequencies.

Visible out to ~ 1 Mpc

Long Wavelength Array

Image EvolutionImage Evolution

VLA 8.5 GHzTaylor et al. 2005, astro-ph/0504363

Long Wavelength Array

Growth of the Radio AfterglowGrowth of the Radio Afterglow

VLA8.5 GHz

Size att+7 days1016 cm

Velocity tot + 30 days~ 0.8 c

Decrease in vexp

Long Wavelength Array

400 km

1 “LWA Station” = 256 antennas Full LWA: 50 stations spread across NM

LWA Overview:LWA Overview:Far Larger than the VLAFar Larger than the VLA

100 m

State of N

ew M

exico

Y

VLA

Long Wavelength Array

Phased DevelopmentPhased Development

Time Phase Description Acronym

2004 0 Existing 74 MHz VLA VLA74

2004-2006 I Long Wavelength Development Array LWDA

2006-2009 II 9 station Long Wavelength Intermediate Array

LWIA

2008-2010 III LWA Core LWAC

2010-2012 IV High Resolution LWA LWA

2010- V LW Operations and Science Center LWOSC

Long Wavelength Array

Full LWA SpecificationsFull LWA Specifications

Frequency range, bandwidth 20-80 MHz, 0.05-3.0 MHz Total collecting area @ 20 MHz 106 m2 @ 60 MHz 105 m2 Angular resolution @ 20 MHz 8” @ 60 MHz 2” Pointing/frequency conversion ti me < 1 ms Sky coverage < 60° zenith distance Sensitivity ( =3 MHz, t=8 hr) @ 20 MHz ~3 mJy @ 60 MHz ~1 mJy Polarization Full Field of view @ 20 MHz ~12° @ 60 MHz ~3° Number of instantaneous baselines 1300 Time resolution 10 ms

Long Wavelength Array

Another recently discovered type of transient Another recently discovered type of transient radio source:radio source:

CGRT J1745-3009 (Hyman et al. 2005)• A periodic flaring to ~1 Jy at 76 min intervals during several months in 2002 • No obvious IR or X-ray counterpart• Tb ~ 1016 K, most likely a coherent emitter• New type of radio source?

Long Wavelength Array

1 10 102 103 104 105 106

Frequency (MHz)

107

106

105

104

103

102

10

LWA Range (deca-meter wave)

Centimeter waves

Millimeter waves

Detecting Extra solar Planets Detecting Extra solar Planets

LWA may detect emission from extra-solar “Jupiters” in outburst. Jupiter exhibits bursts of ~105 Jy at ~ 40 MHz.

~40 MHz

. Interaction of Jupiter’s magnetospherewith the Solar Wind

Bri

ghtn

ess

Long Wavelength Array

Low Frequency Transient Sources Low Frequency Transient Sources

• Radio afterglows (GRBs, SNe, magnetars, …)

• Extra-Solar planets

• Ultra-High Energy Cosmic-ray showers

• Prompt GRB and/or SNe emission

• Giant pulses from pulsars

• Microquasars

• AGN flares

• Microlensing events

• LIGO events?

• Evaporating black holes?

• …

Falcke et al. 2005

Long Wavelength Array

SUMMARYSUMMARY

Opportunity– A pathfinder Long Wavelength (LW) system demonstrates we can finally “see”

through the ionosphere at high sensitivity below 100 MHz. The Long Wavelength Array (LWA) project

– A Long Wavelength system more than 10X size and 100X the power of a recently developed LW VLA pathfinder system.

– A 400 km, completely electronic radio-telescope to be built in NM by the Southwest Consortium, providing arcsecond resolution below 100 MHz.

Goals:– Detection and Monitoring of Transient Sources, Cosmic Evolution, Particle

Acceleration, and Ionospheric Physics

The Long Wavelength Array will open the last poorly explored region of the spectrum - the potential for new discoveries will be high!