Pulsars: The radio/gamma-ray Connection Prospects for pulsar studies with AGILE and GLAST Synergy...
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Transcript of Pulsars: The radio/gamma-ray Connection Prospects for pulsar studies with AGILE and GLAST Synergy...
Pulsars: Pulsars: The radio/gamma-ray The radio/gamma-ray
ConnectionConnection
Pulsars: Pulsars: The radio/gamma-ray The radio/gamma-ray
ConnectionConnection
• Prospects for pulsar studies with AGILE and GLAST
• Synergy with radio telescopes– Timing and follow-up– Radio vs. -ray beams– Polarimetry
Alice K. Harding Alice K. Harding NASA Goddard Space Flight NASA Goddard Space Flight CenterCenter
Radio versus Radio versus -ray beams-ray beamsRadio versus Radio versus -ray beams-ray beams
Compton Gamma-Ray Observatory Compton Gamma-Ray Observatory (CGRO)(CGRO)
Compton Gamma-Ray Observatory Compton Gamma-Ray Observatory (CGRO)(CGRO)
• 7 (+3) gamma-ray pulsars detected
Unresolved questionsUnresolved questionsUnresolved questionsUnresolved questions
• How are particles accelerated so efficiently to 10 How are particles accelerated so efficiently to 10 TeV?TeV?
• Where does this acceleration take place?Where does this acceleration take place?
• Do all pulsars emit Do all pulsars emit -rays?-rays?
• How are radio and How are radio and -ray emission beams related?-ray emission beams related?
• How many radio-quiet How many radio-quiet -ray pulsars (Gemingas) -ray pulsars (Gemingas) are there?are there?
What do we need from radio What do we need from radio telescopes?telescopes?
What do we need from radio What do we need from radio telescopes?telescopes?
• Find more Find more -ray -ray pulsarspulsars
• Study the Study the brightest ones in brightest ones in more detailmore detail
• Sensitive surveysSensitive surveys• Pulse timingPulse timing• Follow-up Follow-up
observationsobservations
• Better pulse profilesBetter pulse profiles• Full-phase Full-phase
polarimetrypolarimetry
AGILE (Astro-rivelatore Gamma a Immagini LEggero)
AGILE (Astro-rivelatore Gamma a Immagini LEggero)
• Italian collaboration
• Launched on 23 April 2007!!
• Operational 2007-2008
• Pair production telescope (30 MeV – 30 GeV)
• Somewhat more sensitive than EGRET
• Should discover > 15-20 new -ray pulsars
• Very large FOV (~20% of sky), factor 4 greater than EGRET
• Broadband (4 decades in energy, 20 MeV – 300 GeV)
• Unprecedented PSF for gamma rays (factor > 3 better than EGRET for E>1 GeV)
• Factor > 30 improvement in Factor > 30 improvement in sensitivitysensitivity
• Much smaller deadtime per event (25 microsec, factor >4,000 better than EGRET)
• No expendables => long mission without degradation
Calorimeter
Tracker
Gamma-Ray Large Area Space Gamma-Ray Large Area Space Telescope (GLAST)Telescope (GLAST)
Gamma-Ray Large Area Space Gamma-Ray Large Area Space Telescope (GLAST)Telescope (GLAST)
e+
e–
ACD [surrounds 4x4 array of TKR towers]
2 instruments:Large Area Telescope (LAT)Gamma-ray Burst Monitor (GBM)
LAT characteristics
Launch in early 2008
Pulsars detected by CGROPulsars detected by CGROPulsars detected by CGROPulsars detected by CGROPrinceton Pulsar Catalog
c. 1995 Only the youngest and/or nearest pulsars were detectable
5 of the 7 radio pulsars with the highest LSD/d2 detected
More pulsars detectable with AGILE and More pulsars detectable with AGILE and GLASTGLAST
More pulsars detectable with AGILE and More pulsars detectable with AGILE and GLASTGLAST
ATNF catalogc. 2007
~53 radio pulsars in error circles of EGRET unidentified sources (18-20 plausible counterparts)
AGILE will discover new -ray pulsars associated with EGRET sources
GLAST will detect sources 25 times fainter or 5 times further away – possibly 50 – 200 new -ray pulsars
Will be able to detect -ray pulsars further than the distance to the Galactic Center
Middle-aged and older pulsars, including millisecond pulsars should be detected in -rays
AGILEAGILE
GLASTGLAST
Radio pulsar propertiesRadio pulsar propertiesRadio pulsar propertiesRadio pulsar properties
Period Surface B
LsdAge
EGRETsources Total
Young radio pulsars and EGRET Young radio pulsars and EGRET sourcessources
Young radio pulsars and EGRET Young radio pulsars and EGRET sourcessources
PSR J2021+3651 in 3EG PSR J2021+3651 in 3EG J2021+3716J2021+3716
P = 104 ms, t = 17 kyrP = 104 ms, t = 17 kyr
(Roberts et al 2002)(Roberts et al 2002)
PSR J1928+1746, 3EG PSR J1928+1746, 3EG J1928+1733 J1928+1733 P = 68 ms, == 82 kyr
Ė = 1.6 1036 erg/s(Cordes et al. 2006)(Cordes et al. 2006)
Predicted GLAST pulsar Predicted GLAST pulsar populationspopulations
Predicted GLAST pulsar Predicted GLAST pulsar populationspopulations
116
30
Slot gap
1680
49
95 (Recycled)
Radio timing needsRadio timing needsRadio timing needsRadio timing needs Collecting enough -ray photons requires years
Young, energetic pulsars are weak and/or noisy
225 pulsars above L ~ 3 x 1034 erg/s
-ray observations would like 1-10 milli-period accuracy on photon arrival times
Large campaigns planned or underway at major radio telescopes (Parkes, Jodrell, Nancay)Need Arecibo to time the Need Arecibo to time the
faint young pulsarsfaint young pulsars ((Approved timing proposal of 22 Approved timing proposal of 22 pulsars with flux below 1 mJy for pulsars with flux below 1 mJy for GLAST)GLAST)
Faint young pulsarsFaint young pulsarsFaint young pulsarsFaint young pulsars
• Young, energetic pulsars with very low fluxes can be timed only with Arecibo
Pulsar name
Radio flux (mJy)
J1930+1852
0.06
J1928+1746
0.25
J2021+3651
0.1
B1853+01 0.19
Puzzling gamma-ray vs. radio profilesPuzzling gamma-ray vs. radio profilesPuzzling gamma-ray vs. radio profilesPuzzling gamma-ray vs. radio profiles
Vela Crab
430 MHz 430 MHz radioradio
>100 >100 MeV MeV --
rayray
Core beam?Core beam?
Cone Cone beam?beam?
Cone beam?Cone beam?
+ core + core beam?beam?
Relative Relative -ray and radio emission altitude-ray and radio emission altitudeRelative Relative -ray and radio emission altitude-ray and radio emission altitude
Crab and Vela
Slot gap -rays
Crab
High-altitude (0.2-0.6 RLC) radio cone
Vela
Low-altitude (0.08 RLC) radio cone
=70o, =55o
Line of sight
Rotating Vector Rotating Vector ModelModel
Rotating Vector Rotating Vector ModelModel
B
= -30
= -0.10
= 90
= 30
= 1170
= -1.50
Full-phase polarimetry – only at Full-phase polarimetry – only at AreciboAreciboFull-phase polarimetry – only at Full-phase polarimetry – only at AreciboAreciboEverett & Weisberg 2001
Only way to determine Only way to determine viewing viewing andand inclination inclination angleangle
= 1620
= 0.960
Follow-up radio observationsFollow-up radio observationsFollow-up radio observationsFollow-up radio observations
Follow-up radio observations of GLAST sources
Radio period
-ray period
Pulsar “suspects”
-ray sources with hard spectra with
cutoffs, low variability, located in pulsar wind nebulae
Unknown millisecond pulsars?
SummarySummarySummarySummary
• Expect 50 – 100 (?) -ray pulsars in next 5 – 10 years
• 100 – 300 (?) more -ray sources that might be pulsars
• Simultaneous radio timing needed to detect -ray pulsars
• Sensitivity needed • To detect unknown faint radio pulsars
counterparts • To study radio vs. -ray beams• To measure polarization at all pulse phases