The Accretion Geometry of the Asynchronous Polar V1432 Aql. (arXiv:2011.13088v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Wang_Q/0/1/0/all/0/1">Qishan Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Qian_S/0/1/0/all/0/1">Shengbang Qian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_L/0/1/0/all/0/1">Liying Zhu</a>
As the only eclipsing asynchronous polar (AP), V1432 Aql provides an
excellent laboratory to study the interaction between the accreted matter and
the magnetic field. However, due to its complex emission, a more physical
understanding of its accretion geometry is still outstanding. Here, we report
an X-ray spectral study using contemporaneous observations from nustar and
swift. We detect significant Compton reflection and confirm earlier reports of
a high soft X-ray temperature $sim52$ keV. We suggest that the
multi-temperature emission is due to a distribution of the specific accretion
rate over the accretion region, which leads to a continuous temperature
distribution over the heated area and explains the high temperature of the soft
X-rays. We interpret these characteristics as the results of the inefficient
accretion in APs. Thus the accretion stream can punch deeply into the
magnetosphere and feed the white dwarf (WD) over a much narrower accretion
region near its equator. Additionally, the broad-band X-rays provide details of
the accretion; the low total accretion rate of $sim 1 times 10^{-10}
~M_{odot} ~yr^{-1}$ contradicts the speculation that V1432 Aql was a recent
nova, while the high specific accretion rate of $sim 5.6 ~g ~cm^{-2} ~s^{-1}$
explains the significant reflection from the surface of the WD.
As the only eclipsing asynchronous polar (AP), V1432 Aql provides an
excellent laboratory to study the interaction between the accreted matter and
the magnetic field. However, due to its complex emission, a more physical
understanding of its accretion geometry is still outstanding. Here, we report
an X-ray spectral study using contemporaneous observations from nustar and
swift. We detect significant Compton reflection and confirm earlier reports of
a high soft X-ray temperature $sim52$ keV. We suggest that the
multi-temperature emission is due to a distribution of the specific accretion
rate over the accretion region, which leads to a continuous temperature
distribution over the heated area and explains the high temperature of the soft
X-rays. We interpret these characteristics as the results of the inefficient
accretion in APs. Thus the accretion stream can punch deeply into the
magnetosphere and feed the white dwarf (WD) over a much narrower accretion
region near its equator. Additionally, the broad-band X-rays provide details of
the accretion; the low total accretion rate of $sim 1 times 10^{-10}
~M_{odot} ~yr^{-1}$ contradicts the speculation that V1432 Aql was a recent
nova, while the high specific accretion rate of $sim 5.6 ~g ~cm^{-2} ~s^{-1}$
explains the significant reflection from the surface of the WD.
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