Browsing by Author "Centre for Astrophysics Research (CAR)"

Now showing items 81-100 of 3233

    • Active galactic nucleus feedback drives the colour evolution of local galaxies 

      Shabala, S.S.; Kaviraj, S.; Silk, J. (2011-06-01)
      We investigate the effects of active galactic nucleus (AGN) feedback on the colour evolution of galaxies found in local (z <0.2) groups and clusters. Galaxies located within the lobes of powerful Fanaroff-Riley type II ...

    • The active nuclei of z < 1.0 3CRR radio sources 

      Hardcastle, M.J.; Evans, D.A.; Croston, J.H. (2009)
      We combine Chandra and XMM–Newton X-ray data from our previous papers with new X-ray observations and with Spitzer mid-infrared (mid-IR) data in order to study the nature of the nuclei of radio galaxies and radio-loud ...

    • Activity and telluric contamination in HARPS observations of Alpha Centauri B 

      Lisogorskyi, Maksym; Jones, Hugh; Feng, Fabo (2019-06-01)
      The Alpha Centauri system is the primary target for planet search as it is the closest star system composed of a solar twin α CenA, a K-dwarf α Cen B, and an M-dwarf Proxima Centauri, which has a confirmed planet in the ...

    • An activity catalogue of southern stars 

      Jenkins, J.S.; Jones, H.R.A.; Tinney, C.G.; Butler, R.P.; McCarthy, C.; Marcy, G.W.; Pinfield, D.J.; Carter, B.D.; Penny, A.J. (2006)
      We have acquired high-resolution echelle spectra of 225 F6-M5 type stars in the southern hemisphere. The stars are targets or candidates to be targets for the Anglo- Australian Planet Search. CaII HK line cores were used ...

    • AD Leonis : Radial velocity signal of stellar rotation or spin-orbit resonance? 

      Tuomi, Mikko; Jones, Hugh R. A.; Anglada-Escudé, Guillem; Butler, R. Paul; Kiraga, Marcin; Vogt, Steven S. (2018-04-16)
      AD Leonis is a nearby magnetically active M dwarf. We find Doppler variability with a period of 2.23 days, as well as photometric signals: (1) a short-period signal, which is similar to the radial velocity signal, albeit ...

    • Adaptive optics observations of the T10 ultracool dwarf UGPS J072227.51-054031.2 

      Bouy, H.; Girard, J.H.V.; Martin, E.L.; Huelamo, N.; Lucas, P.W. (2011)
      Context: With a spectral type of T10, UGPS J072227.51-054031.2 is one of the coolest objects known to date in the solar neighborhood. Aims: Multiple systems are relatively common among early and mid-T dwarfs. We search for ...

    • Agatha: : disentangling periodic signals from correlated noise in a periodogram framework 

      Feng, Fabo; Tuomi, Mikko; Jones, Hugh R. A. (2017-10-01)
      Periodograms are used as a key significance assessment and visualisation tool to display the significant periodicities in unevenly sampled time series. We introduce a framework of periodograms, called "Agatha", to disentangle ...

    • The AGB population in IC 1613 using JHK photometry 

      Sibbons, L. F.; Ryan, Sean G.; Irwin, M.; Napiwotzki, R. (2015-01-01)
      Context. A member of the Local Group, IC 1613 is a gas rich irregular dwarf galaxy that appears to have formed stars continuously over the last 10 Gyr and is relatively independent of external influences from other galaxies. ...

    • The AGB population of NGC 6822 : Distribution and the C/M ratio from JHK photometry. 

      Sibbons, L. F.; Ryan, Sean G.; Cioni, M-R.L.; Irwin, M.; Napiwotzki, R. (2012-04)
      Context. NGC 6822 is an irregular dwarf galaxy and part of the Local Group. Its close proximity and apparent isolation provide a unique opportunity to study galactic evolution without any obvious strong external influences. ...

    • The age of white dwarf companions 

      Weston, S.; Napiwotzki, R. (2009)
      We carried out a spectroscopic investigation of single lined white dwarfs (WDs) in double degenerate (DD) systems and discuss their binary evolution. Simulated spectra of the Hα region are used to derive upper limits on ...

    • AGN activity and the misaligned hot ISM in the compact radio elliptical NGC4278 

      Pellegrini, S.; Wang, J.; Fabbiano, G.; Kim, D.-W.; Brassington, Nicola; Gallagher, J.S.; Trinchieri, G.; Zezas, A. (2012-10-20)
      The analysis of a deep (579ks) Chandra ACIS pointing of the elliptical galaxy NGC4278, which hosts a low-luminosity active galactic nucleus (AGN) and compact radio emission, allowed us to detect extended emission from hot ...

    • AGN candidates in the VVV near-IR galaxy catalogue 

      Baravalle, Laura D.; Schmidt, Eduardo O.; Alonso, M. Victoria; Pichel, Ana; Minniti, Dante; Rodríguez-Kamenetzky, Adriana R.; Masetti, Nicola; Villalon, Carolina; Smith, Leigh C.; Lucas, Philip W. (2023-04-30)
      The goal of this work is to search for Active Galactic Nuclei (AGN) in the Galactic disc at very low latitudes with |b|< 2°. For this, we studied the five sources from the VVV near-infrared (IR) galaxy catalogue that have ...

    • AGN in dwarf galaxies: frequency, triggering processes and the plausibility of AGN feedback 

      Kaviraj, Sugata; Martin, Garreth; Silk, Joseph (2019-10-01)
      While active galactic nuclei (AGN) are considered to be key drivers of the evolution of massive galaxies, their potentially significant role in the dwarf-galaxy regime (M ∗ < 10 9 M ⊙) remains largely unexplored. We combine ...

    • AGN jet-induced feedback in galaxies - II : Galaxy colours from a multicloud simulation 

      Tortora, C.; Antonuccio-Delogu, V.; Romeo, A.D.; Becciani, U.; Kaviraj, S.; Silk, J. (2009-06-01)
      We study the feedback from an active galactic nucleus (AGN) on stellar formation within its host galaxy, mainly using one high-resolution numerical simulation of the jet propagation within the interstellar medium (ISM) of ...

    • AlH lines in the blue spectrum of Proxima Centauri 

      Pavlenko, Yakiv V.; Tennyson, Jonathan; Yurchenko, Sergei N.; Schmidt, Mirek R.; Jones, Hugh R. A.; Lyubchik, Yuri; Mascareño, A. Suárez (2022-11-30)
      The recently-computed ExoMol line lists for isotopologues of AlH are used to analyse the blue spectrum (4000-4500 {\AA}) of Proxima Cen (M5.5 V). Comparison of the observed and computed spectra enables the identification ...

    • Alignment in the orientation of LOFAR radio sources 

      Osinga, E.; Miley, G. K.; Weeren, R. J. van; Shimwell, T. W.; Duncan, K. J.; Hardcastle, M. J.; Mechev, A. P.; Röttgering, H. J. A.; Tasse, C.; Williams, W. L. (2020-08-25)
      Various studies have laid claim to finding an alignment of the polarization vectors or radio jets of active galactic nuclei (AGN) over large distances, but these results have proven controversial and so far, there is no ...

    • Alignment of atmospheric mineral dust due to electric field 

      Ulanowski, Z.; Bailey, J. A.; Lucas, P.W.; Hough, J.; Hirst, E. (2007)
      Optical polarimetry observations on La Palma, Canary Islands, during a Saharan dust episode show dichroic extinction indicating the presence of vertically aligned particles in the atmosphere. Modelling of the extinction ...

    • All-sky Guide Star Catalog for CSST 

      Feng, Hui-Mei; Cao, Zi-Huang; Lam, Man I; Li, Ran; Tian, Hao; Yin, Da-Yi; Yang, Yuan-Yu; Zhang, Xin; Fan, Dong-Wei; Dong, Yi-Qiao; Li, Xin-Feng; Wang, Wei; Li, Long; Jones, Hugh R. A.; Tao, Yi-Han; Nie, Jia-Lu; Wang, Pei-Pei; Liu, Mao-Yuan; Yang, He-jun; Liu, Chao (2024-03-26)
      The China Space Station Telescope (CSST) is a two-meter space telescope with multiple back-end instruments. The Fine Guidance Sensor (FGS) is an essential subsystem of the CSST Precision Image Stability System to ensure ...

    • An all-sky optical catalogue of radio/X-ray sources 

      Flesch, E.; Hardcastle, M.J. (2004-11)
      We present an all-sky catalogue that aligns and overlays the ROSAT HRI, RASS, PSPC and WGA X-ray catalogues and the NVSS, FIRST and SUMSS radio catalogues onto the optical APM and USNO-A catalogues. Objects presented are ...

    • ALMA 400 pc Imaging of a z = 6.5 Massive Warped Disk Galaxy 

      Neeleman, Marcel; Walter, F.; Decarli, Roberto; Drake, Alyssa B.; Eilers, Anna-Christina; Meyer, Romain A.; Venemans, Bram P. (2023-12-01)
      We present 0.″075 (≈400 pc) resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations of the [C ii] and dust continuum emission from the host galaxy of the z = 6.5406 quasar, P036+03. We find that the ...