Comptonization as an origin of the continuum in Intermediate Polars. (arXiv:2102.11789v1 [astro-ph.HE])

Comptonization as an origin of the continuum in Intermediate Polars. (arXiv:2102.11789v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Maiolino_T/0/1/0/all/0/1">T. Maiolino</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Titarchuk_L/0/1/0/all/0/1">L. Titarchuk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_W/0/1/0/all/0/1">W. Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Frontera_F/0/1/0/all/0/1">F. Frontera</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Orlandini_M/0/1/0/all/0/1">M. Orlandini</a>

In this paper we test if the $sim$ 0.3 – 15 keV XMM-Newton EPIC pn spectral
continuum of IPs can be described by the thermal Comptonization compTT model.
We used publicly observations of 12 IPs (AE Aqr, EX Hya, V1025 Cen, V2731 Oph,
RX J2133.7+5107, PQ Gem, NY Lup, V2400 Oph, IGR J00234+6141, IGR J17195-4100,
V1223 Sgr, and XY Ari). We find that our modeling is capable to fit well the
average spectral continuum of these sources. In this framework, UV/soft X-ray
seed photons (with $<kT_s>$ of 0.096 $pm$ 0.013 keV) coming presumably from
the star surface are scattered off by electrons present in an optically thick
plasma (with $<kT_e>$ of 3.05 $pm$ 0.16 keV and optical depth $<tau>$ of 9.5
$pm$ 0.6 for plane geometry) located nearby (on top) to the more central seed
photon emission regions. A soft blackbody (bbody) component is observed in 5
out of the 13 observations analysed, with a mean temperature $<kT_{bb}>$ of
$0.095 pm 0.004$ keV. We observed that the spectra of IPs show in general two
photon indices $Gamma$, which are driven by the source luminosity and optical
depth. Low luminosity IPs show $<Gamma>$ of $1.83 pm 0.19$, whereas high
luminosity IPs show lower $<Gamma>$ of $1.34 pm 0.02$. Moreover, the good
spectral fits of PQ Gem and V2400 Oph indicate that the polar subclass of CVs
may be successfully described by the thermal Comptonization as well.

In this paper we test if the $sim$ 0.3 – 15 keV XMM-Newton EPIC pn spectral
continuum of IPs can be described by the thermal Comptonization compTT model.
We used publicly observations of 12 IPs (AE Aqr, EX Hya, V1025 Cen, V2731 Oph,
RX J2133.7+5107, PQ Gem, NY Lup, V2400 Oph, IGR J00234+6141, IGR J17195-4100,
V1223 Sgr, and XY Ari). We find that our modeling is capable to fit well the
average spectral continuum of these sources. In this framework, UV/soft X-ray
seed photons (with $<kT_s>$ of 0.096 $pm$ 0.013 keV) coming presumably from
the star surface are scattered off by electrons present in an optically thick
plasma (with $<kT_e>$ of 3.05 $pm$ 0.16 keV and optical depth $<tau>$ of 9.5
$pm$ 0.6 for plane geometry) located nearby (on top) to the more central seed
photon emission regions. A soft blackbody (bbody) component is observed in 5
out of the 13 observations analysed, with a mean temperature $<kT_{bb}>$ of
$0.095 pm 0.004$ keV. We observed that the spectra of IPs show in general two
photon indices $Gamma$, which are driven by the source luminosity and optical
depth. Low luminosity IPs show $<Gamma>$ of $1.83 pm 0.19$, whereas high
luminosity IPs show lower $<Gamma>$ of $1.34 pm 0.02$. Moreover, the good
spectral fits of PQ Gem and V2400 Oph indicate that the polar subclass of CVs
may be successfully described by the thermal Comptonization as well.

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