Progress on Pulsar Tools Development

Progress on Pulsar Tools Development

Masaharu Hirayama (GLAST SSC--GSFC/UMBC)

August 9, 2004



GLAST Science Support Center

Pulsar Tools

Data in

Level 0.5

Event display (UI1)

Level 1 (D1)

Pointing/livetime history (D2)

Data extract (U1)

Pt.ing/livetime extractor (U3)

Pulsar period search (A4)

Pulsar ephem. (D4)

Ephemeris extract (U11)

Arrival time

Pulsar phase

correction (U10) assign (U12)

Exposure calc. (U4)

Pulsar profiles (A3)1

Source model def. tool (U7)

LAT Point source catalog (D5)

Catalog Access (U9)

Likelihood (A1)

Astron. catalogs (D6)

Alternative source for testing highlevel analysis

Alternative for making additional cuts on alreadyretrieved event data

Observation simulator (O2)

Pt.ing/livetime simulator (O1)

Data subselection (U2)

Pt.ing/livetime extractor (U3)

Interstellar em. model (U5)

IRFs (D3)

Map gen (U6)

IRF visualization (U8)

GRB LAT DRM gen. (U14)

GRB spectral analysis (A8)2

GRB event binning (A5)

GRB rebinning (A6)2

GRB unbinned spectral analysis (A9)

GRB spectral-temporal modeling (A10)

GRB visualization (U13)

GRB temporal analysis (A7)2

Src. ID (A2)

August 9, 2004

GLAST Science Support Center

GLAST Users' Committee Meeting--2

Pulsars for GLAST LAT

? Pulsars are point sources

? GLAST expected to detect pulsations from 50-100 pulsars

? 10-50% are predicted to be radio quiet like Geminga

? Most need 1 year exposure for detection

? Sparse data

? One photon per 500 pulses (Crab 30 MeV ? 300 GeV)

? Scanning with large FOV

? All sources get some exposure every day throughout a year

? Large number of short observations

Both good and bad news for pulsar timing

August 9, 2004

GLAST Science Support Center

Plot by D.J. Thompson

GLAST Users' Committee Meeting--3

Typical Pulsar Analysis

1. Download data and screen events

For maximum pulse-detection sensitivity, select only events within a small region, typically size of a couple of PSFs

2. Correct event times ? barycentric correction

To cancel Doppler effect resulting from the orbital motions of the Earth and the spacecraft

3. Find pulsar ephemeris at the time of observation

Case 1: Use a radio ephemeris as is Case 2: Scan pulse frequencies around extrapolation of radio

ephemeris Case 3: Search for pulsations if no radio ephemeris is available

4. Calculate pulse phase for each photon 5. Use pulse phases in your analysis

? Pulse shape (or pulse profile) ? Phase-resolved spectrum ? Phase-resolved image

August 9, 2004

GLAST Science Support Center

GLAST Users' Committee Meeting--4

What Pulsar Tools Are Needed?

? Barycentric corrector

Photon arrival time converter (U10)

? Pulsar ephemeris "finder"

Case 1: use a radio ephemeris as is Pulsar ephemerides database (D4) Pulsar ephemeris extractor (U11)

Case 2: scan around a radio ephemeris Pulsar profile & periodicity tests (A3)

Case 3: search for pulsations Pulsar period search (A4)

? Pulse phase calculator

Pulsar phase assignment (U12)

August 9, 2004

GLAST Science Support Center

GLAST Users' Committee Meeting--5

 ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download