High-resolution X-ray spectroscopy of the stellar wind in Vela X-1 during a flare. (arXiv:2007.07260v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Lomaeva_M/0/1/0/all/0/1">M. Lomaeva</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grinberg_V/0/1/0/all/0/1">V. Grinberg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guainazzi_M/0/1/0/all/0/1">M. Guainazzi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hell_N/0/1/0/all/0/1">N. Hell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bianchi_S/0/1/0/all/0/1">S. Bianchi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kuhnel_M/0/1/0/all/0/1">M. Bissinger né Kühnel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Furst_F/0/1/0/all/0/1">F. Fürst</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kretschmar_P/0/1/0/all/0/1">P. Kretschmar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martinez_Chicharro_M/0/1/0/all/0/1">M. Martínez-Chicharro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martinez_Nunez_S/0/1/0/all/0/1">S. Martínez-Núñez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Torrejon_J/0/1/0/all/0/1">J.M. Torrejón</a>
We present a $sim$130 ks observation of the prototypical wind-accreting,
high-mass X-ray binary Vela X-1 collected with XMM-Newton at orbital phases
between 0.12 and 0.28. A strong flare took place during the observation that
allows us to investigate the reaction of the clumpy stellar wind to the
increased X-ray irradiation.
To examine the wind’s reaction to the flare, we performed both time-averaged
and time-resolved analyses of the RGS spectrum and examined potential spectral
changes.
We focused on the high-resolution XMM-Newton RGS spectra and divided the
observation into pre-flare, flare, and post-flare phases. We modeled the
time-averaged and time-resolved spectra with phenomenological components and
with the self-consistent photoionization models calculated via CLOUDY and XSTAR
in the pre-flare phase, where strong emission lines due to resonant transitions
of highly ionized ions are seen.
In the spectra, we find emission lines corresponding to K-shell transitions
in highly charged ions of oxygen, neon, magnesium, and silicon as well as
radiative recombination continua (RRC) of oxygen. Additionally, we observe
potential absorption lines of magnesium at a lower ionization stage and
features identified as iron L lines. The CLOUDY and XSTAR photoionization
models provide contradictory results, either pointing towards uncertainties in
theory or possibly a more complex multi-phase plasma, or both.
We are able to demonstrate the existence of a plethora of variable narrow
features, including the firm detection of oxygen lines and RRC that RGS enables
to observe in this source for the first time. We show that Vela X-1 is an ideal
source for future high-resolution missions, such as XRISM and Athena.
We present a $sim$130 ks observation of the prototypical wind-accreting,
high-mass X-ray binary Vela X-1 collected with XMM-Newton at orbital phases
between 0.12 and 0.28. A strong flare took place during the observation that
allows us to investigate the reaction of the clumpy stellar wind to the
increased X-ray irradiation.
To examine the wind’s reaction to the flare, we performed both time-averaged
and time-resolved analyses of the RGS spectrum and examined potential spectral
changes.
We focused on the high-resolution XMM-Newton RGS spectra and divided the
observation into pre-flare, flare, and post-flare phases. We modeled the
time-averaged and time-resolved spectra with phenomenological components and
with the self-consistent photoionization models calculated via CLOUDY and XSTAR
in the pre-flare phase, where strong emission lines due to resonant transitions
of highly ionized ions are seen.
In the spectra, we find emission lines corresponding to K-shell transitions
in highly charged ions of oxygen, neon, magnesium, and silicon as well as
radiative recombination continua (RRC) of oxygen. Additionally, we observe
potential absorption lines of magnesium at a lower ionization stage and
features identified as iron L lines. The CLOUDY and XSTAR photoionization
models provide contradictory results, either pointing towards uncertainties in
theory or possibly a more complex multi-phase plasma, or both.
We are able to demonstrate the existence of a plethora of variable narrow
features, including the firm detection of oxygen lines and RRC that RGS enables
to observe in this source for the first time. We show that Vela X-1 is an ideal
source for future high-resolution missions, such as XRISM and Athena.
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