Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe NuSTAR view of the Seyfert Galaxy HE 0436-4717
99
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present the multi epoch spectral analysis of HE 0436-4717, a bright Seyfert 1 galaxy serendipitously observed by the high energy satellite NuSTAR four times between December 2014 and December 2015. The source flux shows modest variability within each pointing and among the four observations. Spectra are well modelled in terms of a weakly variable primary power law with constant photon index ($Gamma$=2.01$pm$0.08). A constant narrow ion{Fe} K$alpha$ emission line suggests that this feature has an origin far from the central black hole, while a broad relativistic component is not required by the data. The Compton reflection component is also constant in flux with a corresponding reflection fraction R=0.7$^{+0.2}_{-0.3}$. The iron abundance is compatible with being Solar (A$_{Fe}$=1.2$^{+1.4}_{-0.4}$), and a lower limit for the high energy cut-off E$_c$>280 keV is obtained. Adopting a self-consistent model accounting for a primary Comptonized continuum, we obtain a lower limit for the hot corona electron temperature kT$_e$>65 keV and a corresponding upper limit for the coronal optical depth of $tau_e$<1.3. The results of the present analysis are consistent with the locus of local Seyfert galaxies in the kT$_e$-$tau_e$ and temperature-compactness diagrams.
rate research
Read More
We test the two-corona accretion scenario for active galactic nuclei in the case of the `bare Seyfert 1 galaxy HE 1143-1810. We perform a detailed study of the broad-band UV--X-ray spectral properties and of the short-term variability. We present results of a joint XMM-Newton and NuSTAR monitoring of the source, consisting of 5x20 ks observations, each separated by 2 days, performed in December 2017. The source is variable in flux among the different observations, and a correlation is observed between the UV and X-ray emission. Moderate spectral variability is observed in the soft band. The time-averaged X-ray spectrum exhibits a cut-off at $sim 100$ keV consistent with thermal Comptonization. We detect an iron K$alpha$ line consistent with being constant during the campaign and originating from a mildly ionized medium. The line is accompanied by a moderate, ionized reflection component. A soft excess is clearly present below 2 keV and is well described by thermal Comptonization in a `warm corona with a temperature of $sim 0.5$ keV and a Thomson optical depth of $sim 17-18$. For the hot hard X-ray emitting corona, we obtain a temperature of $sim 20$ keV and an optical depth of $sim 4$ assuming a spherical geometry. A fit assuming a jet-emitting disc (JED) for the hot corona also provides a nice description of the broad-band spectrum. In this case, the data are consistent with an accretion rate varying between $sim 0.7$ and $sim 0.9$ in Eddington units and a transition between the outer standard disc and the inner JED at $sim 20$ gravitational radii. The broad-band high-energy data agree with an accretion flow model consisting of two phases: an outer standard accretion disc with a warm upper layer, responsible for the optical--UV emission and the soft X-ray excess, and an inner slim JED playing the role of a hard X-ray emitting hot corona.
We present measurement of the cut-off energy, a proxy for the temperature of the corona in the nuclear continuum of the Seyfert 1 galaxy 3C 120 using $sim$120 ks of observation from ${it NuSTAR}$. The quality broad band spectrum from 3$-$79 keV has enabled us to measure the Compton reflection component (R) and to constrain the temperature of the coronal plasma. Fitting one of the advanced Comptonization models, ${it compPS}$ to the observed broad band spectrum we derived the kinetic temperature of the electrons in the corona to be $kT_e = 25 pm 2$ keV with Compton ${it y}$ parameter of $y = 2.2 pm 0.1$ for a slab geometry and $kT_e = 26_{-0}^{+2}$ keV with a $y$ of $2.99_{-0.18}^{+2.99}$ assuming a spherical geometry. We noticed excess emission from $sim$10$-$35 keV arising due to Compton reflection and a broad Fe $Kalpha$ line at 6.43 keV with an equivalent width of 60 $pm$ 5 eV. The variations in count rates in the soft (3$-$10 keV) band is found to be more compared to the hard (10$-$79 keV) band with mean fractional variability amplitudes of 0.065$pm$0.002 and 0.052$pm$0.003 for the soft and hard bands respectively. 3C 120 is known to have a strong jet, however, our results indicate that it is either dormant or its contribution if any to the X-ray emission is negligible during the epoch of ${it NuSTAR}$ observation.
Galactic winds driven by active galactic nuclei (AGN) have been invoked to play a fundamental role in the co-evolution between supermassive black holes and their host galaxies. Finding observational evidence of such feedback mechanisms is of crucial importance and it requires a multi-wavelength approach in order to compare winds at different scales and phases. In Tombesi et al. (2015) we reported the detection of a powerful ultra-fast outflow (UFO) in the Suzaku X-ray spectrum of the ultra-luminous infrared galaxy IRAS F11119$+$3257. The comparison with a galaxy-scale OH molecular outflow observed with Herschel in the same source supported the energy-conserving scenario for AGN feedback. The main objective of this work is to perform an independent check of the Suzaku results using the higher sensitivity and wider X-ray continuum coverage of NuSTAR. We clearly detect a highly ionized Fe K UFO in the 100ks NuSTAR spectrum with parameters $N_H = (3.2pm1.5)times 10^{24}$ cm$^{-2}$, log$xi$$=$$4.0^{+1.2}_{-0.3}$ erg s$^{-1}$ cm, and $v_{text{out}} = 0.253^{+0.061}_{-0.118}$ c. The launching radius is likely at a distance of $r ge 16$ $r_s$ from the black hole. The mass outflow rate is in the range $dot{M}_{out}$$simeq$0.5-2 $M_{odot}$ yr$^{-1}$. The UFO momentum rate and power are $dot{P}_{out} simeq$0.5-2 $L_{AGN}/c$ and $dot{E}_{out} simeq$7-27% $L_{AGN}$, respectively. The UFO parameters are consistent between the 2013 Suzaku and the 2015 NuSTAR observations. Only the column density is found to be variable, possibly suggesting a clumpy wind. The comparison with the energetics of molecular outflows estimated in infrared and millimeter wavelengths support a connection between the nuclear and galaxy-scale winds in luminous AGN.
We discuss the results on the hot corona parameters of Active Galactic Nuclei that have been recently measured with NuSTAR. The values taken from the literature of a sample of nineteen bright Seyfert galaxies are analysed. Aims. The aim of this work is to look for correlations between coronal parameters, such as the photon index and cutoff energy (when a phenomenological model is adopted) or the optical depth and temperature (when a Comptonization model is used), with other parameters of the systems like the black hole mass or the Eddington ratio. We analysed the coronal parameters of the nineteen unobscured, bright Seyfert galaxies that are present in the Swift-BAT 70 months catalogue and that have been observed by NuSTAR, alone or simultaneously with others X-rays observatories such as Swift, Suzaku or XMM-Newton. We found an anti-correlation with a significance level > 98% between the coronal optical depth and the coronal temperature of our sample. On the other hand, no correlation between the above parameters and the black hole mass, the accretion rate and the intrinsic spectral slope of the sources is found.
Planck data towards the galaxy M82 are analyzed in the 70, 100 and 143 GHz bands. A substantial north-south and East-West temperature asymmetry is found, extending up to 1 degree from the galactic center. Being almost frequency-independent, these temperature asymmetries are indicative of a Doppler-induced effect regarding the line-of-sight dynamics on the halo scale, the ejections from the galactic center and, possibly, even the tidal interaction with M81 galaxy. The temperature asymmetry thus acts as a model-independent tool to reveal the bulk dynamics in nearby edge-on spiral galaxies, like the Sunyaev-Zeldovich effect for clusters of galaxies.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
