J/ApJ/947/39 3-79keV NuSTAR obs. of Swift J1728.9-3613 (Draghis+, 2023)
The spin of a newborn black hole: Swift J1728.9-3613.
Draghis P.A., Balakrishnan M., Miller J.M., Cackett E., Fabian A.C.,
Miller-Jones J., Ng M., Raymond J.C., Reynolds M., Zoghbi A.
<Astrophys. J., 947, 39 (2023)>
=2023ApJ...947...39D 2023ApJ...947...39D
ADC_Keywords: Black holes; Binaries, X-ray
Keywords: Black hole physics ; High energy astrophysics ; X-ray binary stars ;
Compact binary stars ; Accretion
Abstract:
The origin and distribution of stellar-mass black hole spins are a
rare window into the progenitor stars and supernova events that create
them. Swift J1728.9-3613 is an X-ray binary, likely associated with
the supernova remnant (SNR) G351.9-0.9. An NuSTAR X-ray spectrum of
this source during its 2019 outburst reveals reflection from an
accretion disk extending to the innermost stable circular orbit.
Modeling of the relativistic Doppler shifts and gravitational
redshifts imprinted on the spectrum measures a dimensionless spin
parameter of a=0.86±0.02 (1σ confidence), a small inclination
angle of the inner accretion disk θ<10°, and a subsolar iron
abundance in the disk AFe<0.84. This high spin value rules out a
neutron star primary at the 5σ level of confidence. If the black
hole is located in a still visible SNR, it must be young. Therefore,
we place a lower limit on the natal black hole spin of a>0.82,
concluding that the black hole must have formed with a high spin. This
demonstrates that black hole formation channels that leave an SNR, and
those that do not (e.g., Cyg X-1), can both lead to high natal spin
with no requirement for subsequent accretion within the binary system.
Emerging disparities between the population of high-spin black holes
in X-ray binaries and the low-spin black holes that merge in
gravitational wave events may therefore be explained in terms of
different stellar conditions prior to collapse, rather than different
environmental factors after formation.
Description:
NuSTAR observed Swift J1728.9-3613 on 2019 February 3 starting at
15:01:09 UT under ObsID 90501303002 for a net exposure of 16.7ks,
obtaining an average of ∼600cts/s when combining the two NuSTAR Focal
Plane Module (FPM) sensors.
Objects:
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RA (ICRS) DE Designation(s)
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17 28 58.64 -36 14 37.6 Swift J1728.9-3613 = MAXI J1728-360
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig2.dat 206 309 Light curve of the NuSTAR observation
fig3.dat 671 128 Unfolded and modeled spectrum of Swift J1728.9-3613
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See also:
B/xmm : XMM-Newton Obs. Log (XMM-Newton Science Operation Center, 2012-)
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
J/MNRAS/426/1701 : High-frequency QPO in black hole binaries (Belloni+, 2012)
J/ApJ/800/17 : Mass-transfer sequences in 16 Galactic LMXBs (Fragos+, 2015)
Byte-by-byte Description of file: fig2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [0/308] Sequential bin number
5- 11 F7.1 s Time [0/55500] Time
13- 30 F18.16 ct/s CR [2.7/7] Count rate (panel 1 in Figure 2) (1)
32- 50 F19.17 ct/s e_CR [0.3/2.3] Uncertainty in CR
52- 69 F18.16 --- Ratio1 [4.2/6] 3-7keV to 7-10keV ratio
(panel 2 in Figure 2)
71- 89 F19.17 --- e_Ratio1 [0.1/1.1] Uncertainty in Ratio1
91-108 F18.15 --- Ratio2 [7.4/13.1] 3-7keV to 10-20keV ratio
(panel 3 in Figure 2)
110-128 F19.17 --- e_Ratio2 [0.3/2.3] Uncertainty in Ratio2
130-147 F18.15 --- Ratio3 [34.2/88.5] 3-7keV to 20-79keV ratio
(panel 4 in Figure 2)
149-167 F19.16 --- e_Ratio3 [2.7/61.2] Uncertainty in Ratio3
169-186 F18.15 --- Ratio4 [6.9/19.1] 7-10keV to 20-79keV ratio
(panel 5 in Figure 2)
188-206 F19.16 --- e_Ratio4 [0.6/15.1] Uncertainty in Ratio4
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Note (1): Count rate observed by the FPMA NuSTAR detector across the entire
3-79keV band pass.
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Byte-by-byte Description of file: fig3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [0/127] Sequential bin number
5- 23 F19.16 keV Energy [3/73]? FPMA spectrum, Energy
25- 43 F19.17 keV e_Energy [0.07/7]? Uncertainty in Energy
45- 62 F18.16 keV2 FluxA [0.4/5.2]? FPMA spectrum, Flux
(Panel a in Figure 3) (1)
64- 83 F20.18 keV2 e_FluxA [0.01/0.04]? Uncertainty in FluxA
85- 103 F19.16 keV EnergyATot [3/73]? Total model, FPMA spectrum,
Energy
105- 123 F19.17 keV2 FluxATot [0.4/5.2]? Total model, FPMA spectrum,
Flux (Panel a in Figure 3) (1)
125- 143 F19.16 keV EnergyAdisk [3/73]? Diskbb model component, FPMA
spectrum, Energy
145- 166 E22.17 keV2 FluxAdisk [9.2e-19/3.8]? Diskbb model component,
FPMA spectrum, Flux
(Panel a in Figure 3) (1)
168- 186 F19.16 keV EnergyArelx [3/73]? Relxill model component, FPMA
spectrum, Energy
188- 206 F19.17 keV2 FluxArelx [0.4/1.5]? Relxill model component,
FPMA spectrum, Flux
(Panel a in Figure 3) (1)
208- 226 F19.16 keV EnergyB [3/78] FPMB spectrum, Energy
228- 246 F19.17 keV e_EnergyB [0.079/8] Uncertainty in EnergyB
248- 265 F18.16 keV2 FluxB [0.58/5.3] FPMB spectrum, Flux
(Panel a in Figure 3) (1)
267- 286 F20.18 keV2 e_FluxB [0.01/0.2] Uncertainty in FluxB
288- 306 F19.16 keV EnergyBTot [3/78] Solid line, Total model, FPMB
spectrum, Energy
308- 325 F18.16 keV2 FluxBTot [0.4/5.3] Solid line, Total model, FPMB
spectrum, Flux
(Panel a in Figure 3) (1)
327- 345 F19.16 keV EnergyBdisk [3/78] Diskbb model component, FPMB
spectrum, Energy
347- 368 E22.17 keV2 FluxBdisk [2.5e-21/4] Diskbb model component,
FPMB spectrum, Flux
(Panel a in Figure 3) (1)
370- 388 F19.16 keV EnergyBrelx [3/78] Relxill model component, FPMB
spectrum, Energy
390- 407 F18.16 keV2 FluxBrelx [0.4/1.6] Relxill model component, FPMB
spectrum, Flux
(Panel a in Figure 3) (1)
409- 427 F19.16 keV Energy2Ax [3/73]? Residuals to FPMA spectrum for
constant*TBabs*(diskbb+powerlaw)
model, Energy
429- 447 F19.17 keV e_Energy2Ax [0.07/7]? Uncertainty in Energy2Ax
449- 469 F21.18 --- ResA [-5.7/5]? Residuals to FPMA spectrum
for constant*TBabs*(diskbb+powerlaw)
model, σ
(Panel b in Figure 3)
471- 473 F3.1 --- e_ResA [1]? Uncertainty in ResA
475- 493 F19.16 keV Energy2Bx [3/78] Residuals to FPMB spectrum for
constant*TBabs*(diskbb+powerlaw)
model, Energy
495- 513 F19.17 keV e_Energy2Bx [0.07/8] Uncertainty in Energy2Bx
515- 535 F21.18 --- ResB [-4.6/4.5] Residuals to FPMB spectrum
for constant*TBabs*(diskbb+powerlaw)
model, σ
(Panel b in Figure 3)
537- 539 F3.1 --- e_ResB [1] Uncertainty in ResB
541- 559 F19.16 keV Energy3Ax [3/73]? Residuals to FPMA spectrum for
constant*TBabs*(diskbb+relxill) model,
Energy
561- 579 F19.17 keV e_Energy3Ax [0.07/8]? Uncertainty in Energy3Ax
581- 601 F21.18 --- ResArelx [-3.6/2.5]? Residuals to FPMA spectrum
for constant*TBabs*(diskbb+relxill)
model, σ
(Panel c in Figure 3)
603- 605 F3.1 --- e_ResArelx [1]? Uncertainty in ResArelx
607- 625 F19.16 keV Energy3Bx [3/78] Residuals to FPMB spectrum for
constant*TBabs*(diskbb+relxill) model,
Energy
627- 645 F19.17 keV e_Energy3Bx [0.07/8] Uncertainty in Energy3Bx
647- 667 F21.18 --- ResBrelx [-2.5/3.6] Residuals to FPMB spectrum
for constant*TBabs*(diskbb+relxill)
model, σ
(Panel c in Figure 3)
669- 671 F3.1 --- e_ResBrelx [1] Uncertainty in panel2By
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Note (1): In panel A the Y-axis "Flux" is given in units of
keV2 (photons/s/keV/cm2)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 17-Apr-2025