PULSAR FORMATION RATES HOW HOW ? ? - - PDF document

PULSAR FORMATION RATES

HOW HOW ? ?

PULSAR FORMATION RATES

HOW HOW ? ?

• ❄

Radio Pulsars in NS-NS binaries NS-NS Merger Rate Estimates

small - number observed sample (2 NS -NS in Galactic field) PSR population dominated by faint objects Robust lower limit for the MW: 1 per Myr Upward correction factor for faint PSRs: ~ 1-500

Narayan et al. '91; Phinney '91; Curran & Lorimer '95; Arzoumanian et al. '99; VK et al. '01

Scale-factor calculations:

Statistical "Forward" Approach Calculation

• f Rate

Probability Distribution

It is pos s ible to as s ign s tatis tical s ignificance to NS-NS rate es timates with Monte Carlo s imulations

Kim, VK, Lorimer '03

PSR B1913+16 Distribution of number

• f objects

in

• bserved samples:

Poisson

Likelihood of current sample:

P(1 ;

) =

exp(-

)

The mean of the Poisson distribution

is linearly proportional to the total number of PSRs in the Galaxy:

Using Bayes' theorem we calculate the probability distribution:

2

and the most likely value is:

= 1/

PSR B1913+16

Using the probability distribution we can calculate the most likely rate

as well as the ranges

• f rates at various

confidence levels

Dependence of most likely coalescence rate

• n the PSR LF

parameters:

Rpeak is mostly insensitive to the spatial distribution parameters

Current expectations for most likely advanced (initial) LIGO detection rates of NS-NS inspiral events

• ❋

Rdet 4-100

(1/yr) (1-25) x 10-3

Typical uncertainties:

Radio Pulsars in NS-WD binaries NS-WD Merger Rate Estimates

PSR J0751+1807 PSR J1757- 5322 PSR J1141- 6545 PSR J1141- 6545

(Edwards & Bailes '01) (Kaspi et al. '00) (Lundgren et al. '95)