the extreme dimension: time-variability and the smallest ism scales
DESCRIPTION
The Extreme Dimension: Time-Variability and The Smallest ISM Scales. Dan Stinebring Oberlin College. Some key collaborators. Jim Cordes Barney Rickett, Bill Coles (UCSD) Maura McLaughlin (discovery paper) Oberlin college students. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/1.jpg)
The Extreme Dimension: Time-Variability and
The Smallest ISM Scales
Dan StinebringOberlin College
![Page 2: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/2.jpg)
Some key collaborators
• Jim Cordes• Barney Rickett, Bill Coles (UCSD)
• Maura McLaughlin (discovery paper)
• Oberlin college students ...
![Page 3: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/3.jpg)
Lorimer&Kramer (LK) Fig. 4.2 Sketch showing inhomogeneities in the ISM that result in observed scattering and scintillation effects.
![Page 4: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/4.jpg)
1133+16 dyn & sec
logarithmicgrayscale
lineargrayscale
![Page 5: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/5.jpg)
1133+16 dyn & sec
€
ν
€
t
€
fν
€
ft
logarithmicgrayscale
lineargrayscale
dynamic (or primary) spectrum
secondary spectrum
![Page 6: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/6.jpg)
Coherent radiation scatters off electron inhomogeneities
~ 1 kpc
~ 10 mas
![Page 7: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/7.jpg)
Multi-path interference causesa random diffraction pattern
![Page 8: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/8.jpg)
Relative transverse velocities produce a dynamic spectrum
time
![Page 9: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/9.jpg)
Scattering in a thin screen plusa simple core/halo model canexplain the basics ofscintillation arcs
![Page 10: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/10.jpg)
Time variability of scintillation arcswill allow probing of the ISM on AU size scales
~ 1 kpc
~ 1 – 10 mas
![Page 11: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/11.jpg)
Kolmogorov vs. Gaussian PSF
How to produce a “core/halo” psf?
A Gaussian psf will NOT work: No halo.
![Page 12: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/12.jpg)
Kolmogorov vs. Gaussian PSF
Kolmogorov turbulence DOES work
It produces a psf with broad wings
![Page 13: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/13.jpg)
The substructure persists
and MOVES!
Arecibo observations
January 2005
QuickTime™ and aPhoto - JPEG decompressor
are needed to see this picture.
![Page 14: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/14.jpg)
Hill, A.S., Stinebring, D.R., et al.
2005, ApJ,619, L171
This is the angular velocity of the pulsar across the sky! 51 ± 2 mas/yr
![Page 15: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/15.jpg)
Brisken dyn + secondary
1.2
Walter Brisken (NRAO) et al.“Small Ionized and NeutralStructures,” Socorro, NM, 2006 May 23
![Page 16: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/16.jpg)
B1737+13 movie• Ira asked about the anisotropy of the turbulence ...
![Page 17: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/17.jpg)
Cumulative Delay - Arclets
![Page 18: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/18.jpg)
time delays scale as
€
τ ∝ν−3.6Kolmogorov:
€
τ ∝ν−4.4
![Page 19: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/19.jpg)
Arecibo is the best!
•Raw sensitivity is essential
•Excellent instrumentation•Some bands (e.g. 327 MHz) have low RFI
•(small, focused projects are the key ...)
![Page 20: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/20.jpg)
A new result ...
• 6 months of ~ weekly Arecibo observations of a moderate DM pulsar (B1737+13)
• 4 x 50 MHz bands near 21 cm• Investigate time variability of ScintArc structure and its effect on pulsar timing
![Page 21: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/21.jpg)
How Does this Work?
![Page 22: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/22.jpg)
conjugate time axisConjugate time axis (heuristic)
d
D
€
θ =d
D
y
€
y =λ
d
⎛
⎝ ⎜
⎞
⎠ ⎟D
€
ft =1
Pt=Vxθ xλ€
=λθ
€
Pt =y
V=λ
Vθ
V
incident plane wave (λ)
![Page 23: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/23.jpg)
conjugate freq axisConjugate frequency axis (heuristic)
€
fν =1
Pν=πDθ 2
c
D€
Dθ 2
2
€
θ
€
Pν =δν =c
πDθ 2
incident plane wave (λ)
€
δt =Dθ 2
2c
€
2π δt δν =1
€
δν
![Page 24: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/24.jpg)
where do the parabolas come from ?”
Where do the parabolas come from?
€
fν =πDθ 2
c
€
ft =Vθ
λ
€
fν = ±πDλ2
cV 2
⎛
⎝ ⎜
⎞
⎠ ⎟ ft
2
€
ft€
fν
![Page 25: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/25.jpg)
parabola eqn on data plotB2021+25
€
fν
€
ft€
fν ∝ ft2
![Page 26: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/26.jpg)
€
fν
€
ft Walker et al. 2004
1d “image” on the sky
where do the arclets come from ?”
Where do the “arclets” (inverted parabolas) come from?
![Page 27: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/27.jpg)
Some ObservationalHighlights ...
![Page 28: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/28.jpg)
The Earth Orbits the Sun !!
![Page 29: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/29.jpg)
Effective Velocity
€
Veff⊥ =(1−s)Vp⊥+sVobs⊥−Vscr⊥
Cordes and Rickett 1998, ApJ, 507, 846
€
s ≡Dpsr−screen
Dtotal
€
η=λ2D s (1− s)
2cVeff2
![Page 30: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/30.jpg)
1929+10 velocity plot
![Page 31: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/31.jpg)
Multiple Arcs —>
Multiple “Screens”
![Page 32: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/32.jpg)
“Screen” Locations
fν = η ft
2
€
η=λ2D s (1− s)
2cVeff2
€
Veff⊥ =(1−s)Vp⊥+sVobs⊥−Vscr⊥
![Page 33: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/33.jpg)
PSR 1133+16
€
η=Dλ2 s(1− s)
2cVeff2
€
Veff = (1− s)Dμ psr + sVobs − Vscreen
proper motion (2d)
s=0 s=1
fν = η ft
2
![Page 34: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/34.jpg)
![Page 35: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/35.jpg)
![Page 36: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/36.jpg)
Can We Improve High-accuracyPulsar Timing?
![Page 37: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/37.jpg)
Detection of Gravitational Waves
• Prediction of general relativity and other theories of gravity
• Generated by acceleration of massive object(s)
(K. Thorne, T. Carnahan, LISA Gallery)
• Astrophysical sources:
Inflation era
Cosmic strings
Galaxy formation
Binary black holes in galaxies
Neutron-star formation in supernovae
Coalescing neutron-star binaries
Compact X-ray binaries
(NASA GSFC)
R. N. Manchester (ATNF)
![Page 38: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/38.jpg)
Detecting Gravitational Waves with Pulsars• Observe the arrival times of pulsars with sub-microsecond precision.
• Correct for known effects (spin-down, position, proper motion, ...) through a multi-parameter Model Fit.
•Look at the residuals (Observed - Model) for evidence of correlated timing noise between pulsars in different parts of the sky.
Timing residuals for PSR B1855+09
R. N. Manchester (ATNF)
![Page 39: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/39.jpg)
Cumulative Delay - No Arclets
![Page 40: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/40.jpg)
1133+16 dyn & sec
D. Hemberger
![Page 41: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/41.jpg)
B1737+13 tau_ss + errors (36 epochs)
D. Hemberger
![Page 42: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/42.jpg)
Summary• Interstellar scattering allows us to probe the ISM on AU-size scales.
• Much of the scattering appears to be localized in thin “screens” along the line of sight. We don’t know what these screens are.
• There is evidence for compact (~ AU), dense (~ 100 cm-3) structures of unknown origin.
• Scattering effects are time variable and need to be corrected for in highest precision pulsar timing.
• LOFAR is an excellent telescope with which to pursue these studies!!
Dan StinebringOberlin [email protected]
![Page 43: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/43.jpg)
Detection of Gravitational Waves
• Prediction of general relativity and other theories of gravity
• Generated by acceleration of massive object(s)
(K. Thorne, T. Carnahan, LISA Gallery)
• Astrophysical sources:
Inflation era
Cosmic strings
Galaxy formation
Binary black holes in galaxies
Neutron-star formation in supernovae
Coalescing neutron-star binaries
Compact X-ray binaries
(NASA GSFC)
R. N. Manchester (ATNF)
![Page 44: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/44.jpg)
Detecting Gravitational Waves with Pulsars• Observed pulse periods affected by presence of gravitational waves in Galaxy (psr at time of emission; Earth at time of reception)
• For stochastic GW background, effects at pulsar and Earth are uncorrelated
• Use an array of pulsars to search for the GW background that is correlated because of its effect on the Earth (at time of reception)
• Best limits are obtained for GW frequencies ~ 1/T where T is length of data span
Timing residuals for PSR B1855+09
R. N. Manchester (ATNF)
Want to achieve < 1 us residuals for 10 pulsarsfor 5 years
![Page 45: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/45.jpg)
Name DM RMS Residual (us)J0437-4715 2.65 0.12J1744-1134 3.14 0.65J2124-3358 4.62 2.00J1024-0719 6.49 1.20J2145-0750 9.00 1.44J1730-2304 9.61 1.82J1022+1001 10.25 1.11J1909-3744 10.39 0.22J1857+0943 13.31 2.09J1713+0747 15.99 0.19J0711-6830 18.41 1.56J2129-5721 31.85 0.91J1603-7202 38.05 1.34J0613-0200 38.78 0.83J1600-3053 52.19 0.35J1732-5049 56.84 2.40J1045-4509 58.15 1.44J1643-1224 62.41 2.10J1939+2134 71.04 0.17J1824-2452 119.86 0.88
R. N. Manchester Sept 2006
![Page 46: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/46.jpg)
Timing Behavior vs. Dispersion Measure
0.00
0.50
1.00
1.50
2.00
2.50
3.00
0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00
DM (pc cm^-3)
Timing RMS (microseconds)
data: R. N. Manchester
![Page 47: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/47.jpg)
What we measure ...
€
y(t) = I (t)∗h(t)ISM impulse response function
ISM
€
Rh (τ ) = h(t) h(t − τ ) dt∫the autocorrelation of the impulse response
At the moment, we use the centroid of
€
Rh (τ )
€
h(t)
![Page 48: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/48.jpg)
A new result ...
• 6 months of ~ weekly Arecibo observations of a moderate DM pulsar (B1737+13)
• 4 x 50 MHz bands near 21 cm• Investigate time variability of ScintArc structure and its effect on pulsar timing
![Page 49: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/49.jpg)
B1737+13 secondary spectrum
movie
![Page 50: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/50.jpg)
1133+16 dyn & sec
D. Hemberger
![Page 51: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/51.jpg)
1133+16 dyn & sec
D. Hemberger
![Page 52: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/52.jpg)
Timing Residuals (Observed – Model) for PSR B1855+09
![Page 53: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/53.jpg)
Summary• Pulsars are ideal probes of the ionized ISM
• New phenomena to explore and learn to interpret
• Pulsars may detect gravitational waves before the expensive detectors!
• Larger more sensitive telescopes will provide breakthroughs! LOFAR, SKA ...
Thanks to: Sterrewacht Leiden & NWO
![Page 54: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/54.jpg)
Scintillation Arcs Underlie Other
Scintillation Patterns
![Page 55: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/55.jpg)
Tilted 0355a
psr distance(kpc) V (km/s) sB0823+26 0.38 196 0.36B0834+06 0.72 174 0.33B0919+06 1.2 505 0.59B1133+16 0.27 475 0.49
Roger Foster, GB 140 ft
![Page 56: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/56.jpg)
Tilted 0355b
psr distance(kpc) V (km/s) sB0823+26 0.38 196 0.36B0834+06 0.72 174 0.33B0919+06 1.2 505 0.59B1133+16 0.27 475 0.49
Roger Foster, GB 140 ft
![Page 57: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/57.jpg)
Tilted 0919a
psr distance(kpc) V (km/s) sB0823+26 0.38 196 0.36B0834+06 0.72 174 0.33B0919+06 1.2 505 0.59B1133+16 0.27 475 0.49
![Page 58: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/58.jpg)
Tilted 0919b
psr distance(kpc) V (km/s) sB0823+26 0.38 196 0.36B0834+06 0.72 174 0.33B0919+06 1.2 505 0.59B1133+16 0.27 475 0.49
![Page 59: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/59.jpg)
The Gravitational Wave Spectrum
R. N. Manchester (ATNF)
![Page 60: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/60.jpg)
Sky Distribution of Millisecond PulsarsP < 20 ms and not in globular clusters
R. N. Manchester (ATNF)
![Page 61: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/61.jpg)
Black slide
![Page 62: The Extreme Dimension: Time-Variability and The Smallest ISM Scales](https://reader036.vdocuments.site/reader036/viewer/2022070404/56813bfb550346895da547ca/html5/thumbnails/62.jpg)
Black slide