Abstract
Mergers of neutron stars are known to be associated with short γ-ray bursts 1–4 . If the neutron-star equation of state is sufficiently stiff (that is, the pressure increases sharply as the density increases), at least some such mergers will leave behind a supramassive or even a stable neutron star that spins rapidly with a strong magnetic field 5–8 (that is, a magnetar). Such a magnetar signature may have been observed in the form of the X-ray plateau that follows up to half of observed short γ-ray bursts 9,10 . However, it has been expected that some X-ray transients powered by binary neutron-star mergers may not be associated with a short γ-ray burst 11,12 . A fast X-ray transient (CDF-S XT1) was recently found to be associated with a faint host galaxy, the redshift of which is unknown 13 . Its X-ray and host-galaxy properties allow several possible explanations including a short γ-ray burst seen off-axis, a low-luminosity γ-ray burst at high redshift, or a tidal disruption event involving an intermediate-mass black hole and a white dwarf 13 . Here we report a second X-ray transient, CDF-S XT2, that is associated with a galaxy at redshift z = 0.738 (ref. 14 ). The measured light curve is fully consistent with the X-ray transient being powered by a millisecond magnetar. More intriguingly, CDF-S XT2 lies in the outskirts of its star-forming host galaxy with a moderate offset from the galaxy centre, as short γ-ray bursts often do 15,16 . The estimated event-rate density of similar X-ray transients, when corrected to the local value, is consistent with the event-rate density of binary neutron-star mergers that is robustly inferred from the detection of the gravitational-wave event GW170817.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 198-201 |
| Number of pages | 4 |
| Journal | Nature |
| Volume | 568 |
| Issue number | 7751 |
| DOIs | |
| State | Published - Apr 11 2019 |
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A magnetar-powered X-ray transient as the aftermath of a binary neutron-star merger. / Xue, Y. Q.; Zheng, X. C.; Li, Y.; Brandt, W. N.; Zhang, B.; Luo, B.; Zhang, B. B.; Bauer, F. E.; Sun, H.; Lehmer, B. D.; Wu, X. F.; Yang, G.; Kong, X.; Li, J. Y.; Sun, M. Y.; Wang, J. X.; Vito, F.
In: Nature, Vol. 568, No. 7751, 11.04.2019, p. 198-201.Research output: Contribution to journal › Letter
TY - JOUR
T1 - A magnetar-powered X-ray transient as the aftermath of a binary neutron-star merger
AU - Xue, Y. Q.
AU - Zheng, X. C.
AU - Li, Y.
AU - Brandt, W. N.
AU - Zhang, B.
AU - Luo, B.
AU - Zhang, B. B.
AU - Bauer, F. E.
AU - Sun, H.
AU - Lehmer, B. D.
AU - Wu, X. F.
AU - Yang, G.
AU - Kong, X.
AU - Li, J. Y.
AU - Sun, M. Y.
AU - Wang, J. X.
AU - Vito, F.
PY - 2019/4/11
Y1 - 2019/4/11
N2 - Mergers of neutron stars are known to be associated with short γ-ray bursts 1–4 . If the neutron-star equation of state is sufficiently stiff (that is, the pressure increases sharply as the density increases), at least some such mergers will leave behind a supramassive or even a stable neutron star that spins rapidly with a strong magnetic field 5–8 (that is, a magnetar). Such a magnetar signature may have been observed in the form of the X-ray plateau that follows up to half of observed short γ-ray bursts 9,10 . However, it has been expected that some X-ray transients powered by binary neutron-star mergers may not be associated with a short γ-ray burst 11,12 . A fast X-ray transient (CDF-S XT1) was recently found to be associated with a faint host galaxy, the redshift of which is unknown 13 . Its X-ray and host-galaxy properties allow several possible explanations including a short γ-ray burst seen off-axis, a low-luminosity γ-ray burst at high redshift, or a tidal disruption event involving an intermediate-mass black hole and a white dwarf 13 . Here we report a second X-ray transient, CDF-S XT2, that is associated with a galaxy at redshift z = 0.738 (ref. 14 ). The measured light curve is fully consistent with the X-ray transient being powered by a millisecond magnetar. More intriguingly, CDF-S XT2 lies in the outskirts of its star-forming host galaxy with a moderate offset from the galaxy centre, as short γ-ray bursts often do 15,16 . The estimated event-rate density of similar X-ray transients, when corrected to the local value, is consistent with the event-rate density of binary neutron-star mergers that is robustly inferred from the detection of the gravitational-wave event GW170817.
AB - Mergers of neutron stars are known to be associated with short γ-ray bursts 1–4 . If the neutron-star equation of state is sufficiently stiff (that is, the pressure increases sharply as the density increases), at least some such mergers will leave behind a supramassive or even a stable neutron star that spins rapidly with a strong magnetic field 5–8 (that is, a magnetar). Such a magnetar signature may have been observed in the form of the X-ray plateau that follows up to half of observed short γ-ray bursts 9,10 . However, it has been expected that some X-ray transients powered by binary neutron-star mergers may not be associated with a short γ-ray burst 11,12 . A fast X-ray transient (CDF-S XT1) was recently found to be associated with a faint host galaxy, the redshift of which is unknown 13 . Its X-ray and host-galaxy properties allow several possible explanations including a short γ-ray burst seen off-axis, a low-luminosity γ-ray burst at high redshift, or a tidal disruption event involving an intermediate-mass black hole and a white dwarf 13 . Here we report a second X-ray transient, CDF-S XT2, that is associated with a galaxy at redshift z = 0.738 (ref. 14 ). The measured light curve is fully consistent with the X-ray transient being powered by a millisecond magnetar. More intriguingly, CDF-S XT2 lies in the outskirts of its star-forming host galaxy with a moderate offset from the galaxy centre, as short γ-ray bursts often do 15,16 . The estimated event-rate density of similar X-ray transients, when corrected to the local value, is consistent with the event-rate density of binary neutron-star mergers that is robustly inferred from the detection of the gravitational-wave event GW170817.
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U2 - 10.1038/s41586-019-1079-5
DO - 10.1038/s41586-019-1079-5
M3 - Letter
C2 - 30971846
AN - SCOPUS:85064260758
VL - 568
SP - 198
EP - 201
JO - Nature
JF - Nature
SN - 0028-0836
IS - 7751
ER -