Difference between revisions of "GRO J1744-28"

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(GRO J1744-28 - The Bursting Pulsar)
 
 
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'''Other names''' : 2EG J1746-2852 ([http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=GRO+J1744-28&submit=SIMBAD+search])
 
'''Other names''' : 2EG J1746-2852 ([http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=GRO+J1744-28&submit=SIMBAD+search])
 +
 +
'''Available data''': NuSTAR ObsID 80202027002
  
 
'''Monitoring data''':
 
'''Monitoring data''':
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= Type =  
 
= Type =  
−
Transient Low-mass X-ray Binary exhibiting Type I and II X-ray bursts and pulsations. Next to the Rapid Burster this is one of a few sources where Type II bursts are observed.
+
 
−
Discovered on 1995 December 2 with the Burst And Transient Source Experiment (BATSE) on-board the Compton Gamma Ray Observatory (Kouveliotou et al. 1996)
+
* Transient Low-mass X-ray Binary (Neutron Star)
 +
* Type I and II X-ray bursts and pulsations (next to Rapid Burster one of a few sources where Type II bursts are observed)
 +
* Discovered on 1995 December 2 with the Burst And Transient Source Experiment (BATSE) on-board the Compton Gamma Ray Observatory (<ref name="Kouveliotou96A"/>)  
  
 
= Coordinates =  
 
= Coordinates =  
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* Distance: 7.5-8.5 kpc (<ref name="Augusteijn97"/>, <ref name="Nishiuchi99"/>)
 
* Distance: 7.5-8.5 kpc (<ref name="Augusteijn97"/>, <ref name="Nishiuchi99"/>)
−
* Optical companion: G4 III star (<ref name="MillerJones07"/>, <ref name="Masetti14"/>)
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* Optical companion: G4 III star (<ref name="Gosling07A"/>, <ref name="Masetti14Atel"/>) with M<0.3M<sub>sun</sub> and inclination i>15° (<ref name="Gosling07A"/>)
  
 
== Orbit ==
 
== Orbit ==
  
−
The orbital parameters were approximated to Porb = 11.836 days, T π/2 = 2456696.19880 (JED), ax sin(i) = 2.637 light-sec on the basis of the 2014 outburst with no constrains on the longitude of periastron or eccentricity (<ref name="Pintore14"/>).
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Parameters inferred from 2014 outburst (see <ref name="Pintore14Atel"/>, [https://gammaray.msfc.nasa.gov/gbm/science/pulsars/lightcurves/groj1744.html NSSTC Gamma Ray Astrophysics: GRO J1744])
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See [https://gammaray.msfc.nasa.gov/gbm/science/pulsars/lightcurves/groj1744.html NSSTC Gamma Ray Astrophysics].
+
 
 +
* P<sub>orb</sub> = 11.836 days
 +
* T<sub>π/2</sub> = 2456696.19880 (JED)
 +
* a<sub>x</sub> sin(i) = 2.637 light-sec
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* no constrains on the longitude of periastron or eccentricity
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GRO J1744-28 is special because it exhibits X-ray bursts and pulsations at the same time. Sources which show X-ray bursts are generally believed to have surface conditions (low B-fields) which do not allow pulsations.
 
GRO J1744-28 is special because it exhibits X-ray bursts and pulsations at the same time. Sources which show X-ray bursts are generally believed to have surface conditions (low B-fields) which do not allow pulsations.
−
Pulse period: 2.14Hz <ref name="Finger96"/>
 
  
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The magnetic field strength deduced from disk reflection models lies in the 2–6×10^10 G range (Degenaar et al. 2014), mismatching the values deduced from the CRSF measurements (5.27±0.06 × 10^11 G <ref name="DAi15"/>) by one order of magnitude.
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* Pulse period: 2.14Hz <ref name="Finger96A"/>
 +
* B = 2–6 x 10<sup>10</sup> G from disk reflection models (<ref name="Degenaar14A"/>)
 +
* B = 5.27&#177;0.06 x 10<sup>11</sup> G from CRSF measurements (<ref name="DAi15A"/>)
  
  
 
== Outbursts ==
 
== Outbursts ==
  
−
* 1995 December: Discovery and first report of Type II X-ray bursts (<ref name="Finger96"/>)
+
* 1995 December: Discovery and first report of Type II X-ray bursts (<ref name="Finger96A"/>)
−
* 1996 December: Similar burst characteristics (<ref name="Woods99"/>), CRSF report at 5keV in BeppoSAX data (not yet proven) (<ref name="Doroshenko15"/>)
+
* 1996 December: Similar burst characteristics (<ref name="Woods99"/>), CRSF report at 5keV in BeppoSAX data (not yet proven) (<ref name="Doroshenko15A"/>)
−
* 2014 February: Outburst after 18 years of quiescence (<ref name="Younes15"/>, no CRSF), CRSF report at 5keV, 10keV and 15keV in XMM-Newton/INTEGRAL data, still under debate (<ref name="DAi15"/>)
+
* 2014 February: Outburst after 18 years of quiescence (<ref name="Younes15"/>, no CRSF), CRSF report at 5keV, 10keV and 15keV in XMM-Newton/INTEGRAL data, still under debate (<ref name="DAi15A"/>)
 
* 2017 February: Fourth outburst with ~two orders of magnitude lower luminosity (Koenig et al. in prep.)
 
* 2017 February: Fourth outburst with ~two orders of magnitude lower luminosity (Koenig et al. in prep.)
  
 
== X-ray Spectrum ==
 
== X-ray Spectrum ==
 +
 +
* Spectrum shows typical cut-off powerlaw, like expected from accreting X-ray binary
 +
* Broad iron line at 6-7 keV (disk reflection or fast disk wind <ref name="Degenaar14A"/>)
  
 
=== Cyclotron Features ===
 
=== Cyclotron Features ===
  
−
D’Aì et al. (2015) reported a fundamental CRSF line at 4.68±0.05 keV, with the indication of a second and third harmonic at 10.4 ± 0.1 keV and 15.8+1.3−0.7 keV in XMM-Newton/INTEGRAL data (using gabs).
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Cyclotron line in this source is under debate. GRO J1744−28 is one of the few LMXBs where a CRSF has been reported below 10 keV (other candidates are X1822−371, E<sub>CRSF</sub>=0.7keV <ref name="Iaria15A"/>, SWIFT J0051.8−7320, E<sub>CRSF</sub>=5keV <ref name="Maitra18A"/>)
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Shortly later, Doroshenko et al. (2015) claim to have found a fundamental line at ∼4.5 keV in BeppoSAX data taken during the 1997 outburst (also using gabs).  (<ref name="DAi15"/>, <ref name="Doroshenko15"/>)
+
 
−
This makes GRO J1744−28 one of the few LMXBs where a CRSF has been reported below 10 keV.
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* Fundamental CRSF at 4.68&#177;0.05 keV (gabs, XMM-Newton/INTEGRAL, 2014 outburst <ref name="DAi15A"/>) / ∼4.5 keV (gabs, BeppoSAX, 1997 outburst <ref name="Doroshenko15A"/>)
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(Other candidates are X1822−371 with a claimed cyclotron line energy of 0.7 keV (Iaria et al. 2015) and SWIFT J0051.8−7320 at 5 keV (Maitra et al. 2018)).
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* Indication of second and third harmonic at 10.4&#177;0.1 keV and 15.8<sup>+1.3</sup><sub>-0.7</sub> keV in XMM-Newton/INTEGRAL data (using gabs) (<ref name="DAi15A"/>)
−
)
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* No cyclotron line in low-flux 2017 February outburst (gabs strength upper limit at 0.07keV, 90% CL) (König et al. in prep.)
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The cyclotron line in this source is under debate.
 
  
  
 
'''References'''
 
'''References'''

Latest revision as of 14:54, 26 September 2019


Other names : 2EG J1746-2852 ([1])

Available data: NuSTAR ObsID 80202027002

Monitoring data: Swift/BAT

Type

  • Transient Low-mass X-ray Binary (Neutron Star)
  • Type I and II X-ray bursts and pulsations (next to Rapid Burster one of a few sources where Type II bursts are observed)
  • Discovered on 1995 December 2 with the Burst And Transient Source Experiment (BATSE) on-board the Compton Gamma Ray Observatory ([1])

Coordinates

RA 17h 44‘ 33.09“ DEC -28° 44‘ 27.0“

Binary system

  • Distance: 7.5-8.5 kpc ([2], [3])
  • Optical companion: G4 III star ([4], [5]) with M<0.3Msun and inclination i>15° ([4])

Orbit

Parameters inferred from 2014 outburst (see [6], NSSTC Gamma Ray Astrophysics: GRO J1744)

  • Porb = 11.836 days
  • Tπ/2 = 2456696.19880 (JED)
  • ax sin(i) = 2.637 light-sec
  • no constrains on the longitude of periastron or eccentricity


Pulsations & Magnetic field

GRO J1744-28 is special because it exhibits X-ray bursts and pulsations at the same time. Sources which show X-ray bursts are generally believed to have surface conditions (low B-fields) which do not allow pulsations.

  • Pulse period: 2.14Hz [7]
  • B = 2–6 x 1010 G from disk reflection models ([8])
  • B = 5.27±0.06 x 1011 G from CRSF measurements ([9])


Outbursts

  • 1995 December: Discovery and first report of Type II X-ray bursts ([7])
  • 1996 December: Similar burst characteristics ([10]), CRSF report at 5keV in BeppoSAX data (not yet proven) ([11])
  • 2014 February: Outburst after 18 years of quiescence ([12], no CRSF), CRSF report at 5keV, 10keV and 15keV in XMM-Newton/INTEGRAL data, still under debate ([9])
  • 2017 February: Fourth outburst with ~two orders of magnitude lower luminosity (Koenig et al. in prep.)

X-ray Spectrum

  • Spectrum shows typical cut-off powerlaw, like expected from accreting X-ray binary
  • Broad iron line at 6-7 keV (disk reflection or fast disk wind [8])

Cyclotron Features

Cyclotron line in this source is under debate. GRO J1744−28 is one of the few LMXBs where a CRSF has been reported below 10 keV (other candidates are X1822−371, ECRSF=0.7keV [13], SWIFT J0051.8−7320, ECRSF=5keV [14])

  • Fundamental CRSF at 4.68±0.05 keV (gabs, XMM-Newton/INTEGRAL, 2014 outburst [9]) / ∼4.5 keV (gabs, BeppoSAX, 1997 outburst [11])
  • Indication of second and third harmonic at 10.4±0.1 keV and 15.8+1.3-0.7 keV in XMM-Newton/INTEGRAL data (using gabs) ([9])
  • No cyclotron line in low-flux 2017 February outburst (gabs strength upper limit at 0.07keV, 90% CL) (König et al. in prep.)


References

  1. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Kouveliotou96A
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Augusteijn97
  3. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Nishiuchi99
  4. ↑ 4.0 4.1 Cite error: Invalid <ref> tag; no text was provided for refs named Gosling07A
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Masetti14Atel
  6. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Pintore14Atel
  7. ↑ 7.0 7.1 Cite error: Invalid <ref> tag; no text was provided for refs named Finger96A
  8. ↑ 8.0 8.1 Cite error: Invalid <ref> tag; no text was provided for refs named Degenaar14A
  9. ↑ 9.0 9.1 9.2 9.3 Cite error: Invalid <ref> tag; no text was provided for refs named DAi15A
  10. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Woods99
  11. ↑ 11.0 11.1 Cite error: Invalid <ref> tag; no text was provided for refs named Doroshenko15A
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Younes15
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Iaria15A
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Maitra18A
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