Pulsars seen byFermi
Gamma-ray Space Telescope

9th meeting of the High Energy
Astrophysics Association inJapan, March 2009
N. KawaiTokyo Techon behalf of the Fermi LAT collaboration
1

•gamma rays provide a direct view into Nature’s largest accelerators(neutron stars, black holes)•

gamma rays probe cosmological distances(e.g., γ + γEBL  e+ + e-)•huge leap in key capabilities, including a largely unexplored energy
range; great potential for discovery: e.g. dark matter

LATGBM
Two instruments:

Large Area Telescope (LAT), 20 MeV - >300 GeV
Gamma-ray Burst Monitor (GBM), 10 keV - 25 MeV2

France– IN2P3, CEA/Saclay



Italy
– INFN, ASI, INAF

Japan––––

Hiroshima University
ISAS/JAXA
RIKENTokyo Institute of Technology~390 Members(~95 Affiliated Scientists, 68 Postdocs,and 105 Graduate Students)
construction managed by
Stanford Linear Accelerator Center(SLAC), Stanford University

Sweden– Royal Institute of Technology (KTH)– Stockholm University



United States– Stanford University (SLAC and HEPL/Physics)– University of California at Santa Cruz - Santa Cruz Institute for Particle
Physics– Goddard Space Flight Center– Naval Research Laboratory– Sonoma State University– Ohio State University– University of Washington
3

20 MeV - > 300 GeV> 2000 AGNs

blazars and radiogal = f(θ,z)
evolution z < 5Sag A*

Possibilities

starburst galaxies
galaxy clusters
measure EBL
unIDs

10-50 GRB/year

GeV afterglow
spectra to high energy

γ-ray binaries
Pulsar windsµ-quasar jets

Cosmic rays and clouds

acceleration in Supernova remnants
OB associations
propagation (Milky Way, M31, LMC, SMC)
Interstellar mass tracers in galaxies

Dark Matter

neutralino lines
sub-halo clumps;
e+ + e- spectrum

Pulsars

emission from radio and X-ray pulsars
blind searches for new Gemingas
magnetospheric physics
pulsar wind nebulae
4

LAT images the sky one photon ata time: γ-ray converts in LAT to an

GBMelectron and a positron ; direction andenergy of these particles tell us thedirection and energy of the photon
5Operating modes•

Primary observing mode is Sky
Survey– Full sky every 2 orbits (3 hours)– Uniform exposure, with eachregion viewed for ~30 minutes
every 2 orbits– Best serves majority of science,
facilitates multiwavelength
observation planning– Exposure intervals
commensurate with typicalinstrument integration times forsources– EGRET sensitivity reached indays• Pointed observations when appropriate (selected by peer review in lateryears) with automatic earth avoidance selectable. Target of Opportunity
pointing.
• Autonomous repoints for onboard GRB detections in any mode.
6

Year 1 Science Operations Timeline Plan

“first light”
Observatory
whole skyspacecraft
turn-on checkout

LAT,GBM
turn-oncheck
outweek

week

week

week

Start Year 1
Science Ops

renaming

Start Year 2
Science Opssky survey + ~weekly GRB

pointed + sky
survey tuning

repoints + extraordinary TOOsmonth

12 m o n t h s

LAUNCH

L+60 days
initial tuning/calibrations

Thus far:~20 Atels on flaring sources>100 GRB alerts (GCN)

2ndSymposium
2-5 Nov.

in-depth instrument studies

Release Flaring and Monitored Source Info
GBM and LAT GRB Alerts

continuous
release of new
photon data

GI Cycle 1
Funds Release
Fellows Year 1Start

GI Cycle 2
Proposals
LAT 6-month
high-confidence
source release, GSSC
science tools advance
releaseLAT Year 1 photon
data release PLUS
LAT Year 1 Catalogand Diffuse Model7

Reminder: Features of the Gamma-Ray Sky
seen by EGRET
EGRET all-sky survey (galactic coordinates) E>100 MeV

8Center of the Milky Way

Four-day Data Summation
PSR J1706-44

9

PSR B1055-52

VelaGeminga

Crab

10

PSR B1055-52

VelaGeminga

Crab

11

Questions Fermi LAT can Pursue Regarding
Galactic Sources and Populations

••
•
•••
•

New pulsar detections
Light curve features, using high-statistics profiles
Pulsar spectra and emission models
Relation of pulsars to supernovae (SNe) and pulsar windnebulae (PWNe)
Relation to TeV sources
New classes of pulsars
Refining magnetosphere and emission mechanism models

12II. Fermi LAT results on Pulsars and PWNe
EGRET on CGRO clearly detected 6 pulsars
Fermi LAT is seeing the 6 EGRET pulsars
and finding many more
These are rotation-powered pulsars
some are found using radio ephemerides
depends on regular timing of radio pulsars bycollaborators at Parkes, Jodrell Bank, Nancay, GBT, …

some are found by blind searches

13

Vela (P=89.3 ms)

Geminga (P=237.1 ms)

In its first few days,Fermi confirmed theEGRET pulsars, andbegan finding new γ-raypulsars as well

PSR B1706-44 (P=102.4 ms)

PSR B1055-52 (P=197 ms)

Crab pulsar (P=33.4 ms)

14

Vela – (very) early returns
Everything works!
timingbackground rejectionalignment

on-pulse• precise ephemerides of many pulsars
provided by Parkes, Jodrell Bank,Green bank, Nançay, Arecibo,
Hartbeesthoek, Urumqi, RXTE, XMM...

off-pulse• selecting on-pulse shows point
source• evaluate PSF• alignment of LAT to sky (fit toseveral point sources)

15

First Fermi View of the Vela Pulsar

100 MeV < E < 10 GeV

16

Vela Pulsar – Energy Evolution of Pulse Profile

17

Vela Pulsar – Phase-averaged SED" ! ( E / Ec ) b

N (E) = N0 E e

Consistent with b=1(simple exponential)+0.05! = "1.51"0.04
Ec = 2.9 ± 0.1 GeV

b=2 (superexponential) rejected
at 16.5σ
No evidence formagnetic pairattenuation –Near-surface emission
ruled out18

the classic EGRET 6CTA 119

EGRET 6 and CTA1

CTA1 PulsarPSR B1055-52

PSR B1951+32

Geminga Pulsar

PSR B1706-44

Vela Pulsar

Crab Pulsar

20

Blind Pulsar Search

Fermi Monthly
Catalogue

Candidate PWN/PSR

Blind Pulsar SearchInteresting Candidate

Optimize P-Pdot with Prepfold

Time pulsar with Tempo2
21 21

CTA 1 Pulsar Parameters
Parameter

Value

Frequency (Hz)3.165922467(9)Frequency Derivative (s-2)-3.623(4) ×10-12

Period (ms)315.8637050(9)Period Derivative (s s-1)

3.615(4) ×10-13

Epoch (MJD (TDB))

54647.440 938

R.A. (J2000.0)

00h 07m 01s.56

DEC. (J2000.0)+73° 03´ 08´´.1

Galactic Longitude

119°.65947(3)Galactic Latitude+10°.463348(3)Derived ParametersErot

4.5 x 1035 erg s-1

Bsurf

1.1 x 1013 G

τrot

1.4 x104 years

2222Location in P-Pdot Diagram
CTA 1

1e-11
1e-12
1e-13

310 y

13
10 G

410 y
510 y

1210 G

610 y

1e-14
1e-15

104 y

1013 G

710 y1110 G

810 y1012 G

1e-16
1e-17

1010 G

910 y

1e-18

Period derivative (s/s)

1e-19

910 G

1e-20
1e-21
0.001

0.010.1

1

10Period (s)2323

24 24

CTA 1 pulsar (2 cycles, P=315.86 ms)

3EG J0010 +7309 95% error box
RX J00070+7302+• Exhibits all characteristics of a young highenergy pulsar (characteristic age ~1.4 x 104 yr),which powers a synchrotron pulsar wind
nebula embedded in a larger SNR.

Fermi 95% error box

CTA 1 supernovae remnant• Spin-down luminosity ~1036 erg s-1, sufficient
to supply the PWN with magnetic fields andenergetic electrons.

• γ-ray source at l,b = 119.652, 10.468;
95% error circle radius =0.038° contains the X-ray
source RX J00070+7302, central to the PWN
superimposed on the radio map at 1420 MHz.

• The γ-ray flux from the CTA 1 pulsar
corresponds to about 1-10% of Erot (dependingon beam geometry)• Pulsar off-set from center of radio SNR; roughestimate of the lateral speed of the pulsar is ~450 km/s

2525

CTA1 Summary•CTA1 is the first pulsar whose pulsations were initially found in gamma-rays– Dramatically confirms prior hints that the X-ray point source in theCTA1 SNR is a neutron star
– Pulsations from γ-rays give characteristic age and energetics thatmatch expectations from models of the remnant– Inferred magnetic field is strong, ~ 1013 G•••

Bright enough to time with few ms residuals in 1-week integrations
Blind discovery in a few days; improved statistics with months of data
No source detected yet at pulsar position in off-pulse phases••

CTA1 is just a start: Fermi-LAT is discovering many γ-ray pulsars
Studying this population will shed light on issues such as beaming, emission
models, and population statistics

26 26

First Fermi millisecond pulsar
PSR J0030+0451•••

P = 4.86 ms
Nearby – d = 317 pc
Low spin-down power•

γ-ray and radio are not aligned•

E& sd = 3.3 ! 1033 erg/s

X-ray and radio pulses nearly aligned

Peak separation: 0.4 ± 0.02
Radio lag:
0.14 ± 0.01
XMM

27

Millisecond pulsars detected by Fermi

PULSARPERIOD(ms)
J0030+0451
J0218+4232
J0437-4715
J0613-0200
J1024-0719
J1744-1134
J2124-3358

4.86
2.32
5.76
3.06
5.16
4.07
4.93PERIOD DERIV.

D

Edot-20(kpc)(erg/s)

0.317
3.2
0.15
0.48
0.53
0.48
0.25

3.44E+33
2.44E+35
1.18E+34
1.32E+34
5.31E+33
5.21E+33
6.91E+33(10s/s)

17.74
5.73
0.96
1.85
0.89
2.1

# PHOTONSH-TEST TS

CHANCE PROB

361
455
166
549
135
1014
277

306.8
1289.1
60
14
25.1
57.7

< 4e-08
0.0084< 4e-08< 4e-08
0.00385.04E-05< 4e-0828

Which ones is Fermi detecting?

Those with high‘spin-down flux’1035*- The nearby
population

Spin-down flux (erg/s/kpc2)

E& sd / d 2

1036

1034

1033

1032

1031

1030

0.001

0.01

0.1

Period (s)29III. Fermi Pulsars :Types, Numbers Detected, Distributions
How many pulsars of different types arebeing seen by Fermi?
How are they distributed on the sky?
How are they distributed in period?
One map can convey all of this graphically,
if we represent each pulsar slowed downin frequency (spin period is increased byfactor of 10)30

25 gamma-ray and radio pulsars (including 7 ms psrs)
13 gamma-ray only pulsars
Pulses at 1/10th
real rate

High-confidence detections
EGRET pulsars
through 10/31/2008
young pulsars discovered using radio ephemeris
pulsars discovered in blind search
millisecond pulsars discovered using radio ephemeris31

In the simplest model, the emission should depend on 4 parameters: spin
period, magnetic field, magnetic dipole inclination, and viewing angle
radio emission cone luminosity derived fromrotational energy
Erot = ½ I Ω2.

E = - B2R6Ω4 / c3
 derived parameters:.

rotational age : τ = Ω/2Ω
B field:.

B = 3.2x1019 (PP)1/2 G.

spin-down power: L = IΩΩγ-ray emission
fan beam32

Conclusion

We are just beginning to grasp the new pictureof pulsars in the Galaxy in GeV energies
emerging from Fermi LAT33