Environmental dependence of stellar mass,SFR, and SSFR for the Luminous Red Galaxy (LRG) sample of the SDSS DR7     

X.‐F. Deng  B. Yang  Y.‐P. Ding  P. Jiang 《Astronomische Nachrichten》2012,333(7):644-647

Using the Luminous Red Galaxy (LRG) sample of the Sloan Digital Sky Survey Data Release 7 (SDSS DR7), we investigate the environmental dependence of stellar mass, star formation rate (SFR) and specific star formation rate (SSFR) of LRGs. It is found that stellar mass of LRGs nearly is independent of local environments, and that the environmental dependence of SFR and SSFR in the LRG sample is much weaker than the one in the Main galaxy sample. One possible explanation is that galaxy color and morphology are a pair of galaxy properties most predictive of local environments, while LRGs are a group of galaxies that are likely to be luminous, red and of early types (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Periodic radio variability in NRAO 530： phase dispersion minimization analysis     

Jun-Chao Lu  Jun-Yi Wang  Tao An  Ji-Ming Lin  Hong-Bing Qiu 《天体物理学报》2012,(6):643-650

  相似文献   

Observations of the first light and the epoch of reionization     

Xiaohui Fan 《天体物理学报》2012,(8):865-890

  相似文献   

Discovery of Balmer broad absorption lines in the quasar LBQS 1206＋1052     

Tuo Ji  Ting-Gui Wang  Hong-Yan Zhou  Hui-Yuan Wang 《天体物理学报》2012,(4):369-382

  相似文献   

Peculiar early-type galaxies with central star formation     

Chong Ge  Qiu-Sheng Gu 《天体物理学报》2012,(5):485-499

  相似文献   

Dust extinction and X-ray emission from the starburst galaxy NGC 1482     

N.D. Vagshette  M.B. Pandge  S.K. PandeyM.K. Patil 《New Astronomy》2012,17(5):524-532

We present the results based on multiwavelength imaging observations of the prominent dust lane starburst galaxy NGC 1482 aimed to investigate the extinction properties of dust existing in the extreme environment. (B-V) colour-index map derived for the starburst galaxy NGC 1482 confirms two prominent dust lanes running along its optical major axis and are found to extend up to ∼11 kpc. In addition to the main lanes, several filamentary structures of dust originating from the central starburst are also evident. Though, the dust is surrounded by exotic environment, the average extinction curve derived for this target galaxy is compatible with the Galactic curve, with R_V = 3.05, and imply that the dust grains responsible for the optical extinction in the target galaxy are not really different than the canonical grains in the Milky Way. Our estimate of total dust content of NGC 1482 assuming screening effect of dust is ∼2.7 × 10⁵ M_⊙, and provide lower limit due to the fact that our method is not sensitive to the intermix component of dust. Comparison of the observed dust in the galaxy with that supplied by the SNe to the ISM, imply that this supply is not sufficient to account for the observed dust and hence point towards the origin of dust in this galaxy through a merger like event.Our multiband imaging analysis reveals a qualitative physical correspondence between the morphologies of the dust and Hα emission lines as well as diffuse X-ray emission in this galaxy. Spatially resolved spectral analysis of the hot gas along outflows exhibit a gradient in the temperature. Similar gradient was also noticed in the measured values of metallicity, indicating that the gas in the halo is not yet enriched. High resolution, 2-8 keV Chandra image reveals a pair of point sources in the nuclear region with their luminosities equal to 2.27 × 10³⁹ erg s⁻¹ and 9.34 × 10³⁹ erg s⁻¹, and are in excess of the Eddington-limit of 1.5 M_⊙ accreting source. Spectral analysis of these sources exhibit an absorbed-power law with the hydrogen column density higher than that derived from the optical measurements.  相似文献   

Extragalactic X‐ray surveys: AGN physics and evolution     

A. Comastri  M. Brusa 《Astronomische Nachrichten》2008,329(2):122-126

We review the most important findings on AGN physics and cosmological evolution as obtained by extragalactic X‐ray surveys and associated multiwavelength observations. We briefly discuss the perspectives for future enterprises and in particular the scientific case for an extremely deep (2–3 Ms) XMM survey. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Suzaku observations of clusters of galaxies     

K. Matsushita  Suzaku SWG team 《Astronomische Nachrichten》2008,329(2):139-142

We review results of Suzaku observations of the intracluster medium of clusters of galaxies whose O, Mg, Si, S and Fe abundances have been measured with good accuracy due to the good energy resolution and low background. Metal massto‐light ratios were derived and we will discuss the origin of the metals. We also review the results of the search for bulk motion and hard X‐ray emission. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Fast detection of chaotic behavior in galactic potentials     

G.I. Karanis  Ch.L. Vozikis 《Astronomische Nachrichten》2008,329(4):403-412

In the present paper we apply a new method of distinction between ordered and chaotic motion in galactic potentials. The method uses the Fourier Transform of a series of time intervals each one representing the time that elapsed between two successive points on the Poincaré surface of section. Examples of the methods ability to achieve an early and clear detection of an orbit's behavior are provided using two galactic potentials. The new method can also be applied in order to have an early distinction between ordered and sticky orbits. The method is generalized in order to be used in models with more than two dimensions. Finally we have tried to find an one‐number index to give us the nature of the orbit instead of checking by eye the whole spectrum. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Low‐temperature primordial gas in merging halos     

E. O. Vasiliev  Yu. A. Shchekinov 《Astronomische Nachrichten》2008,329(6):625-631

The thermal regime of the baryons behind shock waves arising in the process of virialization of dark matter halos is governed at certain conditions by radiation of HD lines. A small fraction of the shocked gas can cool down to the temperature of the cosmic microwave background (CMB). We estimate an upper limit for this fraction: at z = 10 it increases sharply from about q_T ∼ 10^–3 for dark halos of M = 5 × 10⁷ M_⊙ to ∼ 0.1 for halos with M = 10⁸ M_⊙. Further increase of the halo mass does not lead however to a significant growth of q_T – the asymptotic value for M ≫ 10⁸ M_⊙ is 0.3. We estimate the star formation rate associated with such shock waves, and show that they can provide a small but not negligible fraction of the star formation. We argue that extremely metal‐poor low‐mass stars in the Milky Way may have been formed from primordial gas behind such shocks. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献