Engineering topics

Trinchieri, G.

Publications and source records attributed to Trinchieri, G..

30 records · Page 2

NASA NTRS1986

The X-ray surface brightness distribution and spectral properties of six early-type galaxies

Detailed analysis is presented of the Einstein X-ray observations of six early-type galaxies. The results show that effective cooling is probably present in these systems, at least in the innermost regions. Interaction with the surrounding medium has a major effect on the X-ray surface brightness distribution at large radii, at least for galaxies in clusters. The data do not warrant the general assumptions of isothermality and gravitational hydrostatic equilibrium at large radii. Comparison of the X-ray surface brightness profiles with model predictions indicate that 1/r-squared halos with masses of the order of 10 times the stellar masses are required to match the data. The physical model of White and Chevalier (1984) for steady cooling flows in a King law potential with no heavy halo gives a surface brightness distribution that resembles the data if supernovae heating is present.

Trinchieri, G.↗

NASA NTRS1986

X-ray studies of galactic and intergalactic gas in the Pegasus I cluster

Einstein Observatory IPC observations of Pegasus I show hot gas in a low density intergalactic medium as well as in a galactic medium within each of the dominant elliptical galaxies, NGC 7619 and NGC 7626. The short central cooling times inferred, of 100 million years or less, suggest that the galaxies contain cooling flows of about 1 solar mass/yr. The intergalactic gas, which is about 5 times less dense than in the least dense of the known Abell clusters, is incapable of stripping the hot gas from the elliptical galaxies or the neutral gas from the spirals. The gas around NGC 7619 appears to be influencing one of the radio lobes of NGC 7626.

Canizares, C. R.↗

NASA NTRS1985

An X-ray study of M51 (NGC 5194) and its companion (NGC 5195)

The galaxy M51 and its companion NGC 5195 were observed with the Einstein High-Resolution Imager. The X-ray observations led to the detection of both galaxies with (0.2-4.0 keV) X-ray luminosities of 3.0 x 10 to the 40th ergs/s and 2.1 x 10 to the 39th ergs/s respectively. M51 and its companion are compared to other spiral and irregular galaxies observed in X-rays, and the various components of the X-ray emission of M51 (i.e., nucleus, point sources, and unresolved extended emission) are discussed.

Palumbo, G. G. C.↗

NASA NTRS1985

A statistical analysis of the Einstein normal galaxy sample. I - Spiral and irregular galaxies

The results of a statistical analysis of 48 spiral and irregular galaxies observed with the Einstein Observatory are reported. It is found that the X-ray luminosity is not directly correlated with the mass of the galaxies, but is strongly correlated with the blue luminosity. This suggests that most X-ray sources, including low-mass binaries, are binary systems belonging to both old disk and young arm Population I components. A real bulge population of X-ray sources exists that can contribute significantly to the X-ray luminosity of early-type spirals. The X-ray emission from a sample of 29 relatively isolated, normal elliptical and S0 galaxies is also studied, and the results are compared to those for the above sample to investigate the origin of the X-ray emission in early-type galaxies and the possible emission mechanisms. The influence of a powerful radio source and the onset of nuclear activity are also examined.

Fabbiano, G.↗

NASA NTRS1985

The gaseous environments of double radio galaxies

A detailed investigation is made of the X-ray emission from five 3CR double radio galaxies, and upper limits are set to the X-ray emissivity of the regions around the radio lobes. These limits, when combined with the expected behavior of hot gas in and around the lobes, show that most of the radio-emitting plasma observed is unlikely to be maintained in static pressure-balance with an external medium. The plasma must expand, and the luminosities of double radio galaxies may therefore decrease with time for most of their lifetimes. A lower limit on the magnetic field strength in the lobes of one-tenth the equipartition value is also derived.

Miller, L.↗

NASA NTRS1985

An X-ray study of M51 (NGC 5194) and its companion (NGC 5195)

Observations of NGC 5194/95 with the Einstein HRI show a very strong nuclear X-ray source, surrounded by a diffuse flux, three point sources, and the companion. The diffuse flux, which correlates well with the radio continuum, is likely to originate from the disk population with an age of approximately 2.1 billion yrs. The large luminosity from the nuclear source, together with optical and radio observations, shows that it belongs to the low luminosity active nuclei, thus extending this class to luminosities of less than about 10 to the 40th erg/s.

Palumbo, G. G. C.↗

NASA NTRS1985

Detailed X-ray observations of M83

X-ray observation of M83 with the Einstein Observatory indicates an extent and shape for this emission that are comparable to those in the blue band, although the inner 2-arcmin region shows a relative X-ray excess that may be accounted for by a clustering of bulge-type X-ray sources in the inner region of the plane of the galaxy. A lack of correlation in high resolution X-ray observations is noted between X-ray emission and the spiral arm pattern, suggesting that most of the X-ray emission from the plane of M83 is due to unresolved sources, belonging to the 'smooth' disk population, whose ages are in the 100 million-1 billion year range. Attention is given to six bright sources in the plane and nuclear region of M83, whose high X-ray luminosities suggest that they are close accreting binaries.

Trinchieri, G.↗

NASA NTRS1984

The complex X-ray emission of NGC 253

High-resolution X-ray observations of the starburst galaxy NGC 253 with the Einstein Observatory show that there are at least four components to its X-ray emission. Eight bright point-like sources were detected. Diffuse emission is visible in the inner disk of NGC 253. A more intense emission region is associated with the nuclear region and with an extension along the southern portion of the minor axis. This last component, in particular, suggests the presence of shock-heated gas associated with outflow from the starburst nucleus. A siimlar feature was seen in the X-ray emission of M82. A comparison between the nuclear regions of NGC 253, M82, and the Milky Way suggests an excess of X-ray emission in the nucleus of M82.

Fabbiano, G.↗

NASA NTRS1984

X-ray observations of spiral galaxies. I - Integrated properties

The results of X-ray observations carried out with the Einstein satellite of 14 nearby field spiral and irregular galaxies are reported. The integrated properties of the galaxies are examined in the luminosity range from 10 to the 38th and 10 to the 40th ergs per sec at 0.5-3.0 keV. It is found that the X-ray luminosities of the galaxies are correlated with both the optical (blue) and the radio luminosities (1.4 GHz). The linear relationship found between the X-ray and the optical blue luminosities suggests a relationship to be between the X-ray luminosity and the stellar content of spiral galaxies exhibiting blue luminosities. On the basis of the correlations, it is proposed that most of the spiral galaxies are relatively young systems of not less than about 10 to the 9th years. Data obtained from the Einstein satellite and those of a previous investigation of the blue galaxies are compared in a table.

Fabbiano, G.↗

NASA NTRS1984

An X-ray survey of a complete sample of 3CR radio galaxies

The X-ray survey of the galaxies, 40 in all, was made with the Einstein Observatory. By comparing the distributions of X-ray luminosities, it is found that 3CR galaxies with double radio morphology (FR 2) and optical emission-line spectra tend to be the more powerful X-ray emitters, with broad-line galaxies at the top of the distribution. It is also found that the X-ray luminosity is strongly correlated with the 5 GHz radio nuclear luminosity. Through an analysis of the complete optical and radio sample with the Spearman partial rank correlation technique, it is determined that nuclear radio luminosity at 5 GHz is correlated with both total radio luminosity at 178 MHz and with galaxy optical luminosity. Other weaker correlations are found of the X-ray luminosity with the total radio luminosity at 178 MHz and the optical luminosity of the galaxy. The results are seen as underlining the importance of nuclear phenomena in radio galaxies and indicating a nuclear origin of their X-ray emission. In addition, it is found that the 3CR emission-line galaxies are similar to both Seyfert galaxies and quasars with double radio morphology in their X-ray properties, strongly reinforcing a unified picture of active nuclei.

Fabbiano, G.↗

NASA NTRS1983

Radio and X-ray observations of the radio halo source in A1367

Radio and X-ray observations of the 'radio halo' in A1367 are presented. The radio spectral index distribution is derived combining data at 610 and 1415 MHz taken with the Westerbork Synthesis Radio Telescope (WSRT). A high-resolution Very Large Array (VLA) map allows us to discriminate between the extended cluster emission and a triple radio source associated with a background stellar object (most probably a QSO) which appears projected onto it. X-ray observations taken with the high-resolution imager on board the Einstein satellite reveal an X-ray source associated with this background object. A second weak X-ray enhancement is found projected onto the extended radio component. Inverse Compton scattering of the synchrotron-emitting particles provides a possible interpretation of such a source. The presence of large-scale magnetic fields and particle acceleration due to the turbulent motion of galaxies through the intergalactic medium is discussed in relationship to the observed peculiarities of the galaxies found in this region.

Gavazzi, G.↗

NASA NTRS1983

X-ray observations of the Antennae /NGC 4038/39/

The merging galaxies NGC 4038/39 were observed with the imaging proportional counter onboard the Einstein Observatory on two separate occasions, 12 months apart. The X-ray map seems to follow the optical contour of the two 'heads', although a softer X-ray component with a different spatial distribution might be present. The harder component is interpreted as being due to the integrated emission of single X-ray sources (like SNRs and X-ray binaries) in the two interacting galaxies. A harder point-like source might also be present in the contact region. The softer component could be thermal emission of gas heated by the interaction between NGC 4038 and NGC 4039. Moreover, a significant difference was observed between the two exposures. An additional X-ray source is present in the first image, but not in the second. If this source is associated with the Antennae, it could be either a very bright X-ray transient or a recent, optically undetected supernova.

Fabbiano, G.↗