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تسجيل مستخدم جديدDetection of a variable ultra-fast outflow in the Narrow Line Seyfert 1 galaxy PG 1448+273
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Relativistically blueshifted absorption features of highly ionised ions, the so-called ultra-fast outflows (UFOs), have been detected in the X-ray spectra of a number of accreting supermassive black holes. If these features truly originate from accretion disc winds accelerated to more than 10 per cent of the speed of light, their energy budget is very significant and they can contribute to or even drive galaxy-scale feedback from active galactic nuclei (AGN). However, the UFO spectral features are often weak due to high ionisation of the outflowing material, and the inference of the wind physical properties can be complicated by other spectral features in AGN such as relativistic reflection. Here we study a highly accreting Narrow Line Seyfert 1 galaxy PG 1448+273. We apply an automated, systematic routine for detecting outflows in accreting systems and achieve an unambiguous detection of a UFO in this AGN. The UFO absorption is observed in both soft and hard X-ray bands with the XMM-Newton observatory. The velocity of the outflow is (26900 +- 600) km/s (~0.09c), with an ionisation parameter of log ({xi} / erg cm s^-1)=4.03_{-0.08}^{+0.10} and a column density above 10^23 cm^-2. At the same time, we detect weak warm absorption features in the spectrum of the object. Our systematic outflow search suggests the presence of further multi-phase wind structure, but we cannot claim a significant detection considering the present data quality. The UFO is not detected in a second, shorter observation with XMM-Newton, indicating variability in time, observed also in other similar AGN.
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Ultra-fast outflows (UFOs) play a key role in the AGN feedback mechanism. It is therefore important to fully characterize their location and energetics. We study the UFO in the latest XMM-Newton archival observation of the NLSy1 galaxy PG 1448+273 by
means of a novel modeling tool, that is, the Wind in the Ionized Nuclear Environment model (WINE). Our detection of the UFO in PG 1448+273 is very robust. The outflowing material is highly ionized, $logxi = 5.53_{-0.05}^{+0.04}$ erg s$^{-1}$ cm, has a large column density, $N_mathrm{H} = 4.5_{-1.1}^{+0.8} times 10^{23}$ cm$^{-2}$, is ejected with a maximum velocity $v_0 = 0.24^{+0.08}_{-0.06},c$ (90% c.l. errors), and attains an average velocity $v_mathrm{avg} = 0.152,c$. WINE succeeds remarkably well to constrain a launching radius of $r_0=77_{-19}^{+31} , r_mathrm{S}$ from the black hole. We also derive a lower limit on both the opening angle of the wind ($theta > 72^{circ}$) and the covering factor ($C_mathrm{f} > 0.69$). We find a mass outflow rate $dot{M}_mathrm{out}=0.65^{+0.44}_{-0.33},M_odot mathrm{yr}^{-1} = 2.0^{+1.3}_{-1.0}, dot{M}_mathrm{acc}$ and a large instantaneous outflow kinetic power $dot{E}_mathrm{out}=4.4^{+4.4}_{-3.6} times 10^{44}$ erg s$^{-1}$ = 24% $L_mathrm{bol}$ = 18% $L_mathrm{Edd}$ ($1 sigma$ errors). We find that a major error contribution on the energetics is due to $r_0$, stressing the importance of an accurate determination through a proper spectral modeling, as done with WINE. Using 20 Swift (UVOT and XRT) observations and the simultaneous OM data from XMM-Newton, we also find that $alpha_mathrm{ox}$ undergoes large variations, with a maximum excursion of $Deltaalpha_mathrm{ox} =-0.7$, after the UFO is detected, leading to a remarkable X-ray weakness. This may point towards a starving of the inner accretion disk due to the removal of matter through the wind.
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