Kuehnel: Created page with "Category:Accreting X-ray Pulsars '''Other names''' : 3U 1626-67 ([http://simbad.u-strasbg.fr/simbad/sim-id?submit=display&bibdisplay=refsum&bibyear1=1850&bibyear2=%24curr..."

2018-04-18T13:35:12Z

Created page with "Category:Accreting X-ray Pulsars '''Other names''' : 3U 1626-67 ([http://simbad.u-strasbg.fr/simbad/sim-id?submit=display&bibdisplay=refsum&bibyear1=1850&bibyear2=%24curr..."

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[[Category:Accreting X-ray Pulsars]]

'''Other names''' : 3U 1626-67 ([http://simbad.u-strasbg.fr/simbad/sim-id?submit=display&bibdisplay=refsum&bibyear1=1850&bibyear2=%24currentYear&Ident=%403399638&Name=V*+KZ+TrA#lab_bib Simbad])

'''Monitoring data''': [http://www.batse.msfc.nasa.gov/batse/pulsar/data/sources/4u1626.html CGRO/BATSE], RXTE/ASM, [http://swift.gsfc.nasa.gov/docs/swift/results/transients/weak/4U1626-67/ Swift/BAT], [http://maxi.riken.jp/top/index.php?cid=1&jname=J1632-674 MAXI], [http://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/4u1626.html Fermi/GBM pulsed flux],[http://heastro.phys.lsu.edu/gbm/image.php?sourceimage=4U1626-67 Fermi/GMB Occultation Project]

= Coordinates =

[http://simbad.u-strasbg.fr/simbad/sim-id?submit=display&bibdisplay=refsum&bibyear1=1850&bibyear2=%24currentYear&Ident=%403399638&Name=V*+KZ+TrA#lab_bib Simbad]

{| class="wikitable"
| RA
| 16h 32' 16.8"
| Dec
| -67° 27' 43"
|-
| RA
| 248.0699
| Dec
| -67.4617
|}

= Binary system =

== Distance ==

The distance is estimated to be between 5 and 13 kpc (<ref name="Chakrabarty98" />).

== Orbit ==

{| class="wikitable"
! Parameter
! Value
! Unit
! Reference
|-
| Porb
| 42
| min
| <ref name="Chakrabarty98" />
|-
| i
| 18
| deg
| <ref name="Levine88" />
|}

'''Note : '''
Porb was obtained from the optical lightcurve, due to reprocessed emission, it has not yet been detected from the neutron star pulsed X-ray emission (<ref name="Jain10" /> and therein).

== Optical Companion ==

'' Names :''' V* KZ TrA (<ref name="McClintock77" />)

{| class="wikitable"
!Parameter
!Value
!Unit
!Reference
|-
|Mass
| 0.04
| M⊙
| <ref name="Levine88" />
|-
|''V''
| ~ 17.5
|
| <ref name="McClintock77" />
|}

= Available data =

* '''ASCA''': one observation in 1993 of ~75 ksec
* '''RXTE''': many monitorings between 1996 and 2010, ranging from 1.2-73.6 ksec in exposure time
* '''Chandra''': three observations (2000, 2003, 2010) > 30 ksec
* '''XMM Newton''': four observations
* '''BeppoSAX''': one observation in 1996
* '''INTEGRAL''': many observations since 2003
* '''Swift''': twelve observations in 2005 and one in 2008
* '''Suzaku''': two observations in 2007 of 100 ksec and in 2011 of 20 ksec, respectively

= Description =

Discovered in 1972 by ''Uhuru'' (<ref name="Giacconi72" />). 4U 1626-67 is a LMXB, with a very compact system composed of a faint blue star and an accreting X-ray pulsar with an almost completely face-on orbit (<ref name="McClintock77" />, <ref name="Levine88" />). The accretion occurs through Roche-lobe overflow (<ref name="Reynolds97" />). The neutron star has a magnetic field in the range 2.4-6.3 x 1012 G (<ref name="Orlandini98b" />). The source has shown stable spin-up or spin-down with two torque reversals in 1991 (<ref name="Bildsten93" />) and 2008 (<ref name="Camero10" />).

== Flux ==

[[File:4u1626-67_flux_camero12.png|350px]]
Figure above obtained from <ref name="Camero12" />.

The source has shown gradually decreasing flux and luminosity (~2.5 x 1034 d2''kpc'' - 10 x 1034 d2''kpc'' (<ref name="Camero12" />) until the torque reversal in 2008, when the intensity started increasing. 
A QPO frequency of 40 mHz, was found from Ginga observations (<ref name="Shinoda90" />). Later with BeppoSAX (<ref name="Owens97" />), ASCA (<ref name="Angelini95" />), RXTE (<ref name="Kommers98" />), and XMM-Newton (<ref name="Krauss07" />) a QPO frequancy of 48 mHz was determined.
<ref name="Kaur08" /> found that the QPO frequency trend in 4U 1626-67 went from positive to a negative. During the spin-up period, the QPO central frequency increased from ~36 mHz in 1983 to ~49 mHz in 1993. In the spin-down period, it gradually decreased at a rate ~(0.2 ± 0.05) mHz yr-1. After the last torque reversal, no QPO was observed (<ref name="Jain10" />).

== Spectrum ==

[[File:4u1626_suzspec_camero12.png|750px|]]
Figure above obtained from <ref name="Camero12" />.

The spectrum consists of a low-energy absorption, a blackbody and a high-energy cutoff power law. 
The spectrum also shows a cyclotron line feature at ~37 keV an iron K fluorescence line at ~6.4 keV and additional emission lines between 0.5 and 1.5 keV (<ref name="Camero12" />). 

== Pulse Profile ==

A 7.7s X-ray pulsar, 4U 1626-67 has a complex, energy- and time-dependent pulse profile (<ref name="Rappaport77" />). 
 
Figure below obtained from <ref name="Rappaport77" />. 
[[File:4u162667_pulse_period_rappaport77_new.png|300px]]
 
 
Figure below obtained from <ref name="Jain10" />. 
[[File:4u1626_pulse_profile_jain10.png|400px]]
 
 

== Pulse Period Evolution ==

The source showed an abrupt torque reversal in mid-1990 (<ref name="Bildsten93" />). 
Observed with Swift/BAT, a second large torque reversal occurred on Feb 2008, with a transition lasting ~150 days (<ref name="Camero10" />). 
 
 
Figure below obtained from <ref name="Camero10" />. 

[[File:4u1626_pulse_per_evol_camero10.png|400px]]

'''References'''

4U 1626-67 - Revision history

Kuehnel: Created page with "Category:Accreting X-ray Pulsars '''Other names''' : 3U 1626-67 ([http://simbad.u-strasbg.fr/simbad/sim-id?submit=display&bibdisplay=refsum&bibyear1=1850&bibyear2=%24curr..."