3 research outputs found
The Active Nucleus of IC4970: A Nearby Example of Merger-Induced Cold-Gas Accretion
We present results from Chandra X-ray and Spitzer mid-infrared observations
of the interacting galaxy pair NGC6872/IC4970 in the Pavo galaxy group and show
that the smaller companion galaxy IC4970 hosts a highly obscured active
galactic nucleus (AGN). The 0.5-10 keV X-ray luminosity of the nucleus is
variable, increasing by a factor 2.9 to 1.7 x 10^{42} erg/s (bright state) on
~100 ks timescales. The X-ray spectrum of the is heavily absorbed (N_H = 3 x
10^{23} cm^{-2}) for power law models with Gamma = 1.5-2.0 and shows a clear
6.4 keV Fe Kalpha line with equivalent width of 144-195 eV. Limits on the
diffuse emission in IC4970 from Chandra X-ray data suggest that the available
power from Bondi accretion of hot interstellar gas may be an order of magnitude
too small to power the AGN. Spitzer images show that 8 micron nonstellar
emission is concentrated in the central 1 kpc of IC4970, consistent with high
obscuration in this region. The mid-infrared colors of the nucleus are
consistent with those expected for a highly obscured AGN. Taken together these
data suggest that the nucleus of IC4970 is a Seyfert 2, triggered and fueled by
cold material supplied to the central supermassive black hole as a result of
the off-axis collision of IC4970 with the cold-gas rich spiral galaxy NGC6872.Comment: 10 pages, 9 figures, submitted to ApJ, MIR flux conversion error
corrected in Table 4, MIR colors and paper text unchange
Cosmology and Cosmogony in a Cyclic Universe
In this paper we discuss the properties of the quasi-steady state
cosmological model (QSSC) developed in 1993 in its role as a cyclic model of
the universe driven by a negative energy scalar field. We discuss the origin of
such a scalar field in the primary creation process first described by F. Hoyle
and J. V. Narlikar forty years ago. It is shown that the creation processes
which takes place in the nuclei of galaxies are closely linked to the high
energy and explosive phenomena, which are commonly observed in galaxies at all
redshifts.
The cyclic nature of the universe provides a natural link between the places
of origin of the microwave background radiation (arising in hydrogen burning in
stars), and the origin of the lightest nuclei (H, D, He and He). It
also allows us to relate the large scale cyclic properties of the universe to
events taking place in the nuclei of galaxies. Observational evidence shows
that ejection of matter and energy from these centers in the form of compact
objects, gas and relativistic particles is responsible for the population of
quasi-stellar objects (QSOs) and gamma-ray burst sources in the universe.
In the later parts of the paper we briefly discuss the major unsolved
problems of this integrated cosmological and cosmogonical scheme. These are the
understanding of the origin of the intrinsic redshifts, and the periodicities
in the redshift distribution of the QSOs.Comment: 51 pages including 1 figur