IUCAA Preprints
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Item Two dimensional galaxy image decomposition(2015-03-13) Wadadekar, Yogesh; Robbason, Braxton; Kembhavi, A. K.Item Filaments and pancakes in the IRAS 1.2 jy redshift catalogue(2015-03-13) Sathyaprakash, B.S.; Sahni, Varun; Shandarian, Sergei; Fisher, K.B.Item Probing the BLR in AGNs using time variability of associated absorption lines(2015-03-01) Srianand, R.; Shankaranarayanan, S.It is know that most of the clouds producing associated absorption in the spectra of AGNs and quasars do not completely cover the background source (continuum + broad emission line region, BLR). We note that the covering factor derived for the absorption is the fraction of photons occulted by. The absorbing clouds, and is not necessarily the same as the fractional area covered. We show that the variability in absorption lines can be produced by the changes in the covering factor caused by the variation in the continuum and the finite light travel time across the BLR. We discuss how such avariability can be distinguished from the variability caused by other effects and how one can use the variability in the covering factor to probe the BLR.Item Luminosity dependent star-formation history of S0 galaxies: evidence from GALEX-SDSS-2MASS-WISE colours(IUCAA, 2015-02) Barway, Sudhanshu; Wadadekar, Yogesh; Vaghmare, KaustubhItem A multiwavelength view of the ISM in the merger remnant Fornax A galaxy(IUCAA, 2015-02) Deshmukh, Shishir; Tate, B.T.; Vagshette, N. D.Item Spectral properties of XRBs in dusty early-type galaxies(IUCAA, 2015-02) Vagshette, N. D.; Pandge, M. B.; Patil, M. K.Item On the origin of the featureless soft X-ray excess emission from the Seyfert 1 galaxy ESO 198–G24(IUCAA, 2015-02) Laha, Sibasish; Dewangan, Gulab Chand; Kembhavi, A.K.Item Neutral hydrogen at high redshifts as a probe of structure formation : 1. Post COBE analysis of CDM and HDM models(2014-11-23) Subramanian, Kandaswamy; Padmanabhan, T.Item Magnetic helicity in galactic dynamos(2002-07-06) Subramanian, KandaswamyMagnetic fields correlated on kiloparsec scales are seen in spiral galaxies. Their origin could be due to amplification of a small seed field by a turbulent galactic dynamo. We review the current status of the galactic dynamo, especially the constraints imposed by magnetic helicity conservation. We estimate the minimal strength of the large-scale magnetic field which could arise inspite of the helicity constraintItem BeppoSAX observation of the rich cluster of galaxies Abell 85(2001-01-06) Lima Neto, G. B.; Pislar, V.; Bagchi, JoydeepWe report the observation of the Intra-Cluster Medium (ICM) of Abell 85 by the X-ray satellite Bep- poSAX. We have both analysed the spectrum obtained in the central 8 arcmin circular region centred on the Very Steep Spectrum Radio Source (VSSRS) and the spec- tra from a number of sub-regions. Analysis of the spec- tra allowed us to independently obtain new estimates of the temperature, metallicity and line-of-sight hydro- gen density column, both globally (T = 6.6 ± 0.3 keV, Z = 0.38 ± 0.06Z⊙ and NH = 5.5+0.9 −0.71020cm−2) and lo- cally. These measures are in good agreement with previ- ous measures based on ROSAT and ASCA data. In the region of the VSRSS, we have tried to disentangle the thermal from the non-thermal X-ray emission. Although we could not do this unambiguously, we have nonethe- less estimated the extended magnetic field using the radio spectrum available for this region.We obtain a lower limit intensity of 0.9µG, consistent with our previous estimate. We also derive α-elements/iron abundance ratios that turn out to be higher than 1. Such a result tends to support the burst model for elliptical galaxies, where a strong galac- tic wind develops early in the galaxy history and type II supernovae (SN) may have the main role in the enrich- ment of the ICM. A two-temperature ICM model was fit- ted in the central region yielding a main component with roughly the mean cluster temperature and a cooler com- ponent with temperature less than 0.1 keV.