Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userHot gaseous atmospheres of rotating galaxies observed with XMM-Newton
103
0
0.0
(
0
)
Added by
Anna Jur\\'a\\v{n}ov\\'a
Publication date
2020
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
X-ray emitting atmospheres of non-rotating early-type galaxies and their connection to central active galactic nuclei have been thoroughly studied over the years. However, in systems with significant angular momentum, processes of heating and cooling are likely to proceed differently. We present an analysis of the hot atmospheres of six lenticulars and a spiral galaxy to study the effects of angular momentum on the hot gas properties. We find an alignment between the hot gas and the stellar distribution, with the ellipticity of the X-ray emission generally lower than that of the optical stellar emission, consistent with theoretical predictions for rotationally-supported hot atmospheres. The entropy profiles of NGC 4382 and the massive spiral galaxy NGC 1961 are significantly shallower than the entropy distribution in other galaxies, suggesting the presence of strong heating (via outflows or compressional) in the central regions of these systems. Finally, we investigate the thermal (in)stability of the hot atmospheres via criteria such as the TI- and C-ratio, and discuss the possibility that the discs of cold gas present in these objects have condensed out of the hot atmospheres.
rate research
Read More
We present results from the XMM-Newton observations of our ongoing program on merging clusters. To date three clusters have been observed, covering the temporal sequence from early to late stage mergers: A1750, A2065 and A3921. Using spatially-resolved spectroscopy of discrete regions, hardness ratio and temperature maps, we show that all three clusters display a complex temperature structure. In the case of A1750, a double cluster, we argue that the observed temperature structure is not only related to the ongoing merger but also to previous merger events. A2065 seems an excellent example of a `compact merger, i.e. when the centres of the two clusters have just started to interact, producing a shock in the ICM. Using comparisons with numerical simulations and complementary optical data, the highly complex temperature structure evident in A3921 is interpreted as an off-axis merger between two unequal mass components. These results illustrate the complex physics of merger events. The relaxation time can be larger than the typical time between merger events, so that the present day morphology of clusters depends not only on on-going interaction but also on the more ancient formation history.
We present a deep XMM-Newton observation of the extremely massive, rapidly rotating, relativistic-jet-launching spiral galaxy 2MASX J23453268-0449256. Diffuse X-ray emission from the hot gaseous halo around the galaxy is robustly detected out to a radius of 160 kpc, corresponding roughly to 35 per cent of the virial radius ($approx 450$ kpc). We fit the X-ray emission with the standard isothermal $beta$ model, and it is found that the enclosed gas mass within 160 kpc is $1.15_{-0.24}^{+0.22} times 10^{11} , rm{M}_{odot}$. Extrapolating the gas mass profile out to the virial radius, the estimated gas mass is $8.25_{-1.77}^{+1.62} times 10^{11} , rm{M}_{odot}$, which makes up roughly 65 per cent of the total baryon mass content of the galaxy. When the stellar mass is considered and accounting for the statistical and systematic uncertainties, the baryon mass fraction within the virial radius is $0.121_{-0.043}^{+0.043}$, in agreement with the universal baryon fraction. The baryon mass fraction is consistent with all baryons falling within $r_{200}$, or with only half of the baryons falling within $r_{200}$. Similar to the massive spiral galaxies NGC 1961 and NGC 6753, we find a low value for the metal abundance of $approx 0.1 {rm{Z}}_{odot}$, which appears uniform with radius. We also detect diffuse X-ray emission associated with the northern and southern lobes, possibly attributed to inverse Compton scattering of cosmic microwave background photons. The estimated energy densities of the electrons and magnetic field in these radio lobes suggest that they are electron-dominated by a factor of 10$-$200, depending on the choice of the lower cut-off energy of the electron spectrum.
Clusters of galaxies contain a hot gas, which emits in X-rays. X-ray telescopes such as XMM-Newton allow to study this plasma to obtain information on physical quantities of these objects. We present here some results on the total mass density distribution of clusters obtained with XMM-Newton based on the hydrostatic approach. These results can be compared to models based on cold dark matter. Generally good agreement is found between observations and models. Furthermore we present a study on physical properties of a distant merging cluster of galaxies, which demonstrates the potential of XMM-Newton studies on this class of objects.
We present a study of the diffuse X-ray emission from the star forming region LMC-N 57 in the Large Magellanic Cloud (LMC). We use archival XMM-Newton observations to unveil in detail the distribution of hot bubbles in this complex. X-ray emission is detected from the central superbubble (SB) DEM L 229, the supernova remnant (SNR) 0532$-$675 and the Wolf-Rayet (WR) bubble DEM L 231 around the WR star Br 48. Comparison with infrared images unveils the powerful effect of massive stars in destroying their nurseries. The distribution of the hot gas in the SNR and the SB display their maxima in regions in contact with the filamentary cold material detected by IR images. Our observations do not reveal extended X-ray emission filling DEM L 231, although several point-like sources are detected in the field of view of this WR nebula. The X-ray properties of Br 48 are consistent with a binary WN4$+$O as proposed by other authors. We modeled the X-ray emission from the SB and found that its X-ray emission can be simply explained by pressure-driven wind model, that is, there is no need to invoke the presence of a SN explosion as previously suggested. The pressure calculations of the hot gas confirms that the dynamical evolution of the SB DEM L 229 is dominated by the stellar winds from the star cluster LH 76.
Solar and stellar flares are powerful events which produce intense radiation across the electromagnetic spectrum. Multiwavelength observations are highly important for understanding the nature of flares, because different flare-related processes reveal themselves in different spectral ranges. To study the correlation between thermal and nonthermal processes in stellar flares, we have searched the databases of Kepler (optical observations) and XMM-Newton (soft X-rays) for the flares observed simultaneously with both instruments; nine distinctive flares (with energies exceeding $10^{33}$ erg) on three stars (of K-M spectral classes) have been found. We have analyzed and compared the flare parameters in the optical and X-ray spectral ranges; we have also compared the obtained results with similar observations of solar flares. Most of the studied stellar flares released more energy in the optical range than in X-rays. In one flare, X-ray emission strongly dominated, which could be caused either by soft spectrum of energetic electrons or by a near-limb position of this flare. The X-ray flares were typically delayed with respect to and shorter than their optical counterparts, which is partially consistent with the Neupert effect. Using the scaling laws based on the magnetic reconnection theory, we have estimated the characteristic magnetic field strengths in the stellar active regions and the sizes of these active regions as about $25-70$ G and $250,000-500,000$ km, respectively. The observed stellar superflares appear to be scaled-
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
