Radio MSPulsars in Terzan 5

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Radio MS-Pulsars in Terzan 5

• Jason Hessels
• (UvA)

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Outline
1. Observed population of radio pulsars in
Terzan5 2. Spin Frequency Distribution of ms
radio pulsars. 3. Future Prospects.
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Terzan 5 Massive dense cluster
Contours 20-cm VLA Greyscale I-band image
Diffuse steep spectrum emission
From Fruchter Goss 2000
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Terzan 5 Search Summary

• Pulsar Spigot data 1024 (now 2048) lags, 82 ?s
  samp., 600 MHz (clean!) centered at 1950 MHz.
• 30 new pulsars found (Ransom, Hessels, Stairs et
  al. 2005, Hessels, Ransom, Stairs et al. 2006)
• 33 total 17 binary,
• 16 isolated).
• 5 fastest pulsars in the
• GC system.
• 3 of the 5 fastest pulsars
• anywhere.
• 6 binaries with e 0.25
• (e.g. Ter5Z e 0.76,
• Ter5Q e 0.72).
• 3 new eclipsing systems
• (also the 3 fastest).

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Terzan 5 Pulsars
Timing Positions
Pulse Profiles
GC MSP catalogue http//www.naic.edu/pfreire/GCp
sr.html
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Spin distribution of Ter5 vs. 47 Tuc
KS test suggests drawn from different
distributions at 95 confidence.Also, e.g.
NGC6441 and NGC6440 have predominantly slow MSPs
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PSR J1748-2446ad a.k.a. Ter5ad

• Pspin 1.396 ms
• ?spin 716 Hz
• Musical tone F-F
• S1950 80 ?Jy
• Porb 1.09 d
• Mc,min 0.14 MSun
• Eclipsed for 50 of its orbit.
• Irregular eclipses.
• Bloated companion.
• Like NGC6397A?
• X-ray counterpart.

Hessels, Ransom, Stairs et al. 2006, Science,
311, 1901
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Timing of Ter5ad and Ter5P

• Both Ter5ad and Ter5P are eclipsing (Ter5ad
  variably), very fast spinning (P 1.4/1.7ms), and
  appear to have bloated companions (like NGC
  6397A).
• Extreme orbital variability Ter5ad requires 5
  orbital period derivatives to whiten the
  residuals. Ter5P requires 11 (work by Paulo
  Freire).
• Ter5A (11ms) also shows orbital and eclipse
  variability (Nice et al.), though a proper
  analysis requires removal of eclipse delays.

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Highly irregular eclipses of Ter5ASee also e.g.
Nice Thorsett 1992
0.8GHz
2GHz
2GHz
2GHz
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Currently Known Population

• Pulsars with P
• 42 known in the Galactic field, 106 in globular
  clusters

Frequencies 100-1000 Hz
Periods 1-10ms
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Currently Known Population
Observational biases
Frequencies 100-1000 Hz

• Scattering
• Dispersion
• Sampling time
• Binary motion
• Eclipses
• Steep spectra

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MSPs in Globular Clusters
0.2 Msun He WD companion
Orbital Period Distribution
0.03 Msun dwarf companion
Beware selection effects
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amax?1/(?T2)
Acceleration Search
Frequencies 100-1000 Hz
Periods 1-10ms
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Spigot now has twice the frequency resolution
Keep an eye out for GUPPI
0.78-MHz channels
0.78-MHz channels
0.39-MHz channels
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Eclipsing Millisecond PulsarsAre many of the
fastest-spinning pulsars hidden?
Five of the 10 fastest-spinning pulsars show
eclipses. 5 of the 10 fastest-spinning pulsars
are found in Terzan 5
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Eclipsing Millisecond PulsarsAre many of the
fastest-spinning pulsars hidden?

• Low flux density (S19500.08mJy) suggests other
  very fast radio pulsars await discovery.
• Are we unable to detect a significant portion of
  the fastest pulsars because of self-obscuration?
  (also Tavani 1991)
• 4 of the 5 fastest-spinning pulsars are
  eclipsing, and the exception, B193721 is odd
  because it is isolated and quite bright.

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X-ray Imaging of Terzan 5
Heinke et al. 2006 1-6 keV 50 sources with Lx
3x1031 ergs/s 33 sources with Lx 1032
ergs/s (largest known in GC) 13 soft sources are
qLMXBs
45-ks Chandra ACIS-S courtesy Craig Heinke
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P
ad
Pulsars within 1 of an X-ray source M and
CX30 are offset by 0.52 P and CX10 are offset
by 0.40, Var? ab and CX29 are offset by
0.29 ad and CX13 are offset by 0.28,
Var? Where are A and O ??? (From Heinke et al.
2006)
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Hard source
P
ad
ad
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Hard source
P
ad
ad
P
ad
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Luminosity Function
8.2kpc
5.5kpc
Ter5 vs. 47Tuc
Freire et al. 2008
The solution SKA at high 5-10GHz