gamma-ray pulsarsgamma-ray pulsars: spin down vs luminosity & the distance problem peter r. den...
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Gamma-ray Pulsars:
spin down vs luminosity &
the distance problem
Peter R. den HartogStanford University (HEPL/KIPAC)
hartog@stanford.edu
Parkes 50 years, Parkes, NSW, Australia, November 2 , 2011
obo LAT-collaboration, pulsar timing consortium and pulsar search consortium
in preparation for Fermi LAT 2nd Pulsar Catalog
Tuesday, November 29, 2011
EMBARGO
This talk contains EMBARGOED material
Please do not cite (tweet, blog) any details of this talk until TOMORROW afternoon EST
There will be a NASA press conference on the announcement of the
100th Fermi gamma-ray pulsar
Tuesday, November 29, 2011
Fermi Gamma-ray Space TelescopeTwo instruments:• Large Area Telescope (LAT)• Gamma-ray Burst Monitor (GBM).
International collaboration: USA, France, Germany, Italy, Japan, Sweden.
Lifetime 5 to 10 years.
LAT • Energy range: 20 MeV to >300 GeV. • Large FOV of 2.4 sr.• Survey observation mode (with a few exceptions).
Whole sky seen in two orbits (eight times per day).• Effective area at 1 GeV ~7000 cm2 • Angular resolution: ~ 3.5° at 0.1 GeV, 0.6° at 1 GeV• Point-source location accuracy ~1’ @ 1GeV
Tuesday, November 29, 2011
0 0.05 0.15 0.35 0.74 1.5 3.1 6.2 13 25 50
Gamma-ray sources: From EGRET to Fermi
Second Fermi LAT catalog (2FGL)Fermi LAT all-sky gamma-ray map >100 MeV
271 sources (9 years)6 Pulsars
1873 sources (2 years)87 Pulsars
J0534+2200 (Crab)J0633+1746 (Geminga)J0835-4510 (Vela)J1057-5226J1709-4429J1952+3252
Few ‘marginal’ detections including 1 millisecond PSR (PSR-J0218+4232; Kuiper et al. 2000)
Abdo et al. 2011 arxiv.org/abs/1108.1435v1
Tuesday, November 29, 2011
Gamma-ray sources: From EGRET to Fermi
Second Fermi LAT catalog (2FGL)Fermi LAT all-sky gamma-ray map >100 MeV
J0534+2200 (Crab)J0633+1746 (Geminga)J0835-4510 (Vela)J1057-5226J1709-4429J1952+3252
Few ‘marginal’ detections including 1 millisecond PSR (PSR-J0218+4232; Kuiper et al. 2000)
Abdo et al. 2011 arxiv.org/abs/1108.1435v1
Tuesday, November 29, 2011
Pulsar Timing consortiumCampaign to time 224 high E pulsars.(best gamma-ray candidates, but unstable spin-down rate.)
Nançay and Jodrell Bank provide us with another 500 ephemerides!
.
Parkes (Australia)
Nançay (France)
Jodrell Bank (England)
RXTE
Green Bank Telescope (USA)
Arecibo (Puerto Rico)
Smith et al. A&A 492, 293 (2008)
Tuesday, November 29, 2011
Pulsar Timing consortiumCampaign to time 224 high E pulsars.(best gamma-ray candidates, but unstable spin-down rate.)
Nançay and Jodrell Bank provide us with another 500 ephemerides!
.
Parkes (Australia)
Nançay (France)
Jodrell Bank (England)
RXTE
Green Bank Telescope (USA)
Arecibo (Puerto Rico)
Smith et al. A&A 492, 293 (2008) FERMI
Tuesday, November 29, 2011
Current γ-ray pulsar population
Counter now at 101 Fermi γ-ray PSRs. (Tomorrow special press event for 100th Fermi PSR!)1/3 gamma-selected pulsars. Previously unknown pulsars discovered in blind searches + Geminga1/3 millisecond pulsars, More to come from recent discovered MSPs in Fermi Unassociated sources1/3 radio-selected discovered using radio ephemerides
Tuesday, November 29, 2011
Filling in the P - Pdot
E = 1035 erg s-1.
Abdo et al., ApJS 187, p460, 2010
Tuesday, November 29, 2011
Filling in the P - Pdot
E = 1033 erg s-1.
E = 1035 erg s-1.
Tuesday, November 29, 2011
Emission mechanism & geometry
Different theoretical models exist to explain the observed gamma-ray emission.They assume different emission processes and origins in the magnetosphere → different emission geometry.
Different models predict different light curves (e.g. number of peaks, separation, radio/gamma lag, ratio of radio-loud/radio-quiet).
Different γ-ray spectra are expected (i.e. exponential cutoff vs super-exponential cutoff)
Some answers thanks to Fermi:• The gamma-ray emission from the bulk of the gamma-ray pulsars is outer magnetospheric
• There are many gamma-ray millisecond pulsars
• The fraction of radio-loud to radio-quiet gamma-ray pulsars is 2:1
Stick around for the next talk by Matthew Kerr
Tuesday, November 29, 2011
δ radio-gamma offset
Δ Separation between γ peaks
Interpreting light curves
Abdo et al. 2009, ApJ, 700, 1059
Determine: Δ, δ, finda) which model best matches (if any)b) for which α, ζ valuesc) Determine fΩ and refine Lγ .
Watters et al. 2009, ApJ 695, 1289Romani & Watters 2010, ApJ 714, 810
20 30 40 50 60 70 80 90
TPC eps=+0.2
80
OG eps=-0.280604020
60
40
20
OG eps=0.0 OG eps=+0.2
TPC eps=-0.2 TPC eps=0.0
Tuesday, November 29, 2011
b=1 high-altitude emission.Strong magnetic fields would attenuate gamma rays if the emission were close to the surface b>1 (super-exponential)
Spectral index Γ~1.5Cutoff E0 ~2.5 GeVEnergy flux > 100 MeV ~ 4.3e-10 ergs cm-2s-1
b
Spectral shape: Power Law + Exponential Cutoff
LAT spectra for PSR J2021+3651Abdo et al. 2009, ApJ, 700, 1059
● young, radio-selected young, gamma-selected▲ millisecond pulsar
Abdo et al., ApJS 187, p460, 2010
Tuesday, November 29, 2011
0
1
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Pulsar Phase0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
)M
eVlo
g(E
1.5
2
2.5
3
3.5
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4.5
5
0
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Cutoff energy and spectral index vs. pulse phase. 203 fixed-counts (750) phase bins.
Vela (PSR J0835−4510)
Cou
nts
0
5000
10000 >0.02 GeVP1
P3
P2
Cou
nts
0
5
10
15 >20.0 GeV
Cou
nts
0
50
8.0 20.0 GeV
Cou
nts
0
200
4003.0 8.0 GeV
Cou
nts
0
1000
2000 1.0 3.0 GeV
Cou
nts
0
2000
4000 0.3 1.0 GeV
Cou
nts
0
1000
2000
3000 0.1 0.3 GeV
Pulsar Phase0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Cou
nts
0
50
1000.02 0.1 GeV
Cou
nts
0
5000
10000 >0.02 GeVP1
P3
P2
Cou
nts
0
5
10
15 >20.0 GeV
Cou
nts
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50
8.0 20.0 GeV
Cou
nts
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200
4003.0 8.0 GeV
Cou
nts
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1000
2000 1.0 3.0 GeV
Cou
nts
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2000
4000 0.3 1.0 GeV
Cou
nts
0
1000
2000
3000 0.1 0.3 GeV
Pulsar Phase0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Cou
nts
0
50
1000.02 0.1 GeV
Energy (GeV)110 1 10
)1 s2
dN/d
E (e
rg c
m2 E
1010
910
810
0.135 0.133
0.05± = 1.820.67 GeV± = 3.98CE
Energy (GeV)110 1 10
)1 s2
dN/d
E (e
rg c
m2 E
1010
910
810
0.226 0.220
0.08± = 1.170.17 GeV± = 1.51CE
Energy (GeV)110 1 10
)1 s2
dN/d
E (e
rg c
m2 E
1010
910
810
0.324 0.315
0.05± = 1.330.48 GeV± = 4.05CE
Energy (GeV)110 1 10
)1 s2
dN/d
E (e
rg c
m2 E
1010
910
810
0.563 0.562
0.04± = 1.550.66 GeV± = 4.89CE
Abdo et al., ApJ 696, 1084, 2009;Abdo et al., ApJ 713, 154, 2010 Spectra from four phase bins
Pulse profile as function of phase
Tuesday, November 29, 2011
Pulsar detectability
Abdo et al., ApJS 187, p460, 2010
Fermi LAT pulsar catalog I contained 46 γ-ray pulsars: 17 γ-ray-selected, 21 radio-selected, 8 MSPs
The high E pulsars seem to favour L∝E0.5 while lower E pulsars may favour L∝E...
Luminosity determinations depend very sensitive on distance estimates and uncertainties.Note 8 out of 17 γ-ray-selected PSRs with distance estimates.
... .
Tuesday, November 29, 2011
PSRCATII distances status
For all radio pulsars we have DM (they are in pretty good condition)DM distances for: ~66% (not necessarily used in PSRCATII)
~33% Pulsars with other estimate(s) How reliable are they?Work in progress
The Gamma-ray only pulsars are a problem..(arguably the more interesting ones)~25% of all pulsars without any distance estimate. Also work in progress
Tuesday, November 29, 2011
PSRCATII distances status
Parallax: 13 Fermi PSRs with parallax measurements, however 5 of them <5σ
DM distances: have now 20% errors.Arguably some are less reliable. Identify problem regions and maybe assign a larger error?
Associations: continue trying to find them in literature/ archives/ surveys/ X-ray / WDs Long process. In general it takes several hours per pulsar.
Tuesday, November 29, 2011
PSRCATII distances
Parallax:Programs have started to measure parallaxes of Fermi PSRs. Maybe some good numbers of new distances for Fermi Pulsar Catalog III.
NE201X: (Cordes et al.)Hard work is going on for new Galactic electron-density model to replace NE2001. Looking good for PSRCATIII
Tuesday, November 29, 2011
Fermi collaboration birthday wishes
Happy 50th birthday PARKES
Thank you for all the hard work,
awesome science and great collaborations
Tuesday, November 29, 2011
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