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Title: Evolution of Spin, Orbital, and Superorbital Modulations of 4U 0114+650

Abstract

We report a systematic analysis of the spin, orbital, and superorbital modulations of 4U 0114+650, a high-mass X-ray binary that consists of one of the slowest spinning neutron stars. Using the dynamic power spectrum, we found that the spin period varied dramatically and is anticorrelated with the long-term X-ray flux variation that can be observed using the Rossi X-ray Timing Explorer ASM, Swift BAT, and the Monitor of All-sky X-ray Image. The spin-up rate over the entire data set is consistent with previously reported values; however, the local spin-up rate is considerably higher. The corresponding local spin-up timescale is comparable to the local spin-up rate of OAO 1657−415, indicating that 4U 0114+650 could also have a transient disk. Moreover, the spin period evolution shows two ∼1000-day spin-down/random-walk epochs that appeared together with depressions of the superorbital modulation amplitude. This implies that the superorbital modulation was closely related to the presence of the accretion disk, which is not favored in the spin-down/random-walk epochs because the accretion is dominated by the direct wind accretion. The orbital period is stable during the entire time span; however, the orbital profile significantly changes with time. We found that the depth of the dip near themore » inferior conjunction of the companion is highly variable, which disfavors the eclipsing scenario. Moreover, the dip was less obvious during the spin-down/random-walk epochs, indicating its correlation with the accretion disk. Further monitoring in both X-ray and optical bands could reveal the establishment of the accretion disk in this system.« less

Authors:
;  [1];  [2];  [3];  [4]
  1. Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong)
  2. Graduate Institute of Astronomy, National Central University, Jhongli 32001, Taiwan (China)
  3. Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan (China)
  4. Department of Mathematics, Fu Jen Catholic University, New Taipei City 24205, Taiwan (China)
Publication Date:
OSTI Identifier:
22663381
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 844; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; AMPLITUDES; BINARY STARS; COMPARATIVE EVALUATIONS; CORRELATIONS; ECLIPSE; MASS; MODULATION; NEUTRON STARS; PULSARS; RANDOMNESS; SPECTRA; SPIN; STAR EVOLUTION; STELLAR WINDS; X RADIATION

Citation Formats

Hu, Chin-Ping, Ng, C.-Y., Chou, Yi, Lin, Lupin Chun-Che, and Yen, David Chien-Chang, E-mail: cphu@hku.hk. Evolution of Spin, Orbital, and Superorbital Modulations of 4U 0114+650. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA79A3.
Hu, Chin-Ping, Ng, C.-Y., Chou, Yi, Lin, Lupin Chun-Che, & Yen, David Chien-Chang, E-mail: cphu@hku.hk. Evolution of Spin, Orbital, and Superorbital Modulations of 4U 0114+650. United States. doi:10.3847/1538-4357/AA79A3.
Hu, Chin-Ping, Ng, C.-Y., Chou, Yi, Lin, Lupin Chun-Che, and Yen, David Chien-Chang, E-mail: cphu@hku.hk. Thu . "Evolution of Spin, Orbital, and Superorbital Modulations of 4U 0114+650". United States. doi:10.3847/1538-4357/AA79A3.
@article{osti_22663381,
title = {Evolution of Spin, Orbital, and Superorbital Modulations of 4U 0114+650},
author = {Hu, Chin-Ping and Ng, C.-Y. and Chou, Yi and Lin, Lupin Chun-Che and Yen, David Chien-Chang, E-mail: cphu@hku.hk},
abstractNote = {We report a systematic analysis of the spin, orbital, and superorbital modulations of 4U 0114+650, a high-mass X-ray binary that consists of one of the slowest spinning neutron stars. Using the dynamic power spectrum, we found that the spin period varied dramatically and is anticorrelated with the long-term X-ray flux variation that can be observed using the Rossi X-ray Timing Explorer ASM, Swift BAT, and the Monitor of All-sky X-ray Image. The spin-up rate over the entire data set is consistent with previously reported values; however, the local spin-up rate is considerably higher. The corresponding local spin-up timescale is comparable to the local spin-up rate of OAO 1657−415, indicating that 4U 0114+650 could also have a transient disk. Moreover, the spin period evolution shows two ∼1000-day spin-down/random-walk epochs that appeared together with depressions of the superorbital modulation amplitude. This implies that the superorbital modulation was closely related to the presence of the accretion disk, which is not favored in the spin-down/random-walk epochs because the accretion is dominated by the direct wind accretion. The orbital period is stable during the entire time span; however, the orbital profile significantly changes with time. We found that the depth of the dip near the inferior conjunction of the companion is highly variable, which disfavors the eclipsing scenario. Moreover, the dip was less obvious during the spin-down/random-walk epochs, indicating its correlation with the accretion disk. Further monitoring in both X-ray and optical bands could reveal the establishment of the accretion disk in this system.},
doi = {10.3847/1538-4357/AA79A3},
journal = {Astrophysical Journal},
number = 1,
volume = 844,
place = {United States},
year = {Thu Jul 20 00:00:00 EDT 2017},
month = {Thu Jul 20 00:00:00 EDT 2017}
}