Observations of compact binaries
Sponsored Links
This presentation is the property of its rightful owner.
1 / 28

Observations of compact binaries using XMM-Newton PowerPoint PPT Presentation


  • 96 Views
  • Uploaded on
  • Presentation posted in: General

Observations of compact binaries using XMM-Newton. Gavin Ramsay. What is a compact binary?. Two stars orbiting around each other on timescales less than ~few hrs. One star a white dwarf the other a star similar to the Sun but less massive. How compact are they?. The Sun!.

Download Presentation

Observations of compact binaries using XMM-Newton

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Observations of compact binaries

using XMM-Newton

Gavin Ramsay


What is a compact binary?

Two stars orbiting around each

other on timescales less than ~few hrs

One star a white dwarf the other a star

similar to the Sun but less massive


How compact are they?

The Sun!

A compact binary with 2hr orbital period


Characteristics depend on the magnetic

field of the white dwarf

B<10^4G

B~10^6G

B>10^7G


XMM-Newton


XMM-MSSL polar survey

A survey of 40 strongly magnetic binary systems

Surprise was that so many were in

low accretion states: ~half of the systems

Not there!

Important input for population synthesis models

Ramsay et al (2004)


EP Dra - an eclipsing polar


EP Dra - accretion dip and eclipse

Ramsay et al (2004)


The X-ray spectra of polars

Long been the subject of great

controversy. Standard model suggests

L_soft/Lhard~1/2


Survey suggests that most polars show

X-ray spectrum consistent to that predicted

by standard model. However….

Ramsay & Cropper (2004)


EU UMa - shows very little hard X-ray flux

Some systems, however, show

emission properties not

predicted by the standard

accretion model. One proposal

is that dense blobs of material

are present in the accretion

flow which do not generate

hard X-rays. Not clear why

some systems have blobs while

others do not. Not related to

magnetic field strength.

Ramsay et al (2004)


XMM-Newton observations of Intermediate Polars

B<10^4G

B~10^6G

B>10^7G


FO Aqr: P_spin=20.9min, Porb=4.9hrs

Evans et al (2004)


FO Aqr: X-ray spectrum

Huge absorption dip due accretion ‘curtain’

Evans et al (2004)


Disc accreting binaries

B<10^4G

B~10^6G

B>10^7G


YZ Cnc: Porb~2.1hrs

Hakala et al (2004)


YZ Cnc: X-ray spectrum

Hakala et al (2004)


Evidence for jets?

Model with no-blue shift

Model with blue shift of

1200km/s

Hakala et al (2004)


ULTRA-compact binary: Porb<10min

Jupiter

Ultra-compact

binary


RX J1914+24: Porb 569 sec (9.5min)

Ramsay et al (2005)


Models fall into accretion and

non-accreting model.

Accreting models predict it would

spin down over time.

Non-accreting model suggests it

would spin-up over time (the electric

star model).


RX J1914+24: spinning up

Ramsay et al (2005)


Spining up at a rate of 6.6x10^-12s/s

Ramsay et al (2005)


What is the electric star model?

Sounds far fetched - but!….


We know it operates on Jupiter


RX J1914+24: X-ray spectrum

Very odd!

Ramsay et al (2005)


Both ultra-compacts have been discovered

in X-rays. Search for more!

Programme to search for ultra-compact

systems in XMM-Newton and Chandra

archives.

Have yet to find one but have discovered

lots of flare stars!


Trenholme, Ramsay & Foley (2004)


  • Login