Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userNIR Observations of the QSO 3C 48 Host Galaxy
59
0
0.0
(
0
)
Authors
J. Zuther
Ask ChatGPT about the research
No Arabic abstract
In this paper we present new near infrared (NIR) imaging and spectroscopic data of the quasar 3C 48 and its host galaxy. The data were obtained with the ESO-VLT camera ISAAC.We report the first detection of the apparent second nucleus 3C 48A about 100NE of the bright QSO nucleus in the NIR bands J, H, and Ks. 3C 48A is highly reddened with respect to the host, which could be due to warm dust, heated by enhanced star formation or by interstellar material intercepting the radio jet. In fact, all colors on the host galaxy are reddened by several magnitudes of visual extinction. Imaging and initial spectroscopy also reveal a stellar content of about 30% to the overall QSO-light in the NIR. These results are important input parameters for future models of the stellar populations by taking extinction into account.
rate research
Read More
In this contribution we present new near-infrared (NIR) data on the quasar 3C 48 and its host galaxy, obtained with ISAAC at the Very Large Telescope (ESO, Chile). The NIR images and spectra reveal a reddening of several magnitudes caused by extinction due to molecular material and dust within the host galaxy. For the first time we clearly identify the highly reddened potential second nucleus 3C 48A about 100 northeast of the quasar position in the NIR. Its reddening can be accounted for by warm dust, heated by star formation or an interaction of the 3C 48 radio jet with the interstellar medium, or both. The NIR colors and the CO(6-3) absorption feature both give a stellar contribution of about 30 percent to the QSO-dominated light. These results will contribute to the question of how the nuclear activity and the apparent merger process are influencing the host galaxy properties and they will improve existing models.
The QSO 3C 48 and its host galaxy constitute a nearby template object of the proposed merger-driven evolutionary sequence from ULIRGs to QSOs. In this contribution multi-wavelength observations and N-body simulations studying the structural and compositional properties of this late-stage major merger will be presented. Key questions addressed will be the nature of the apparent second nucleus 3C 48A and absence of a counter tidal tail. The results will be used to review the role of 3C 48 in the ULIRG-QSO evolutionary scenario.
The likely merger process and the properties of the stellar populations in the I Zw 1 host galaxy are analyzed on the basis of multi-wavelength observations (with the ISAAC camera at the Very Large Telescope (VLT/UT1) of the European Southern Observatory (ESO), Chile (Paranal), with the interferometer of the Berkeley-Illinois-Maryland Association (BIMA), USA (Hat Creek/California), and with the IRAM Plateau de Bure Interferometer (PdBI), France) and N-body simulations. The data give a consistent picture of I Zw 1, with properties between those of ultra-luminous infrared galaxies (ULIRGs) and QSOs as displayed by transition objects in the evolutionary sequence of active galaxies.
We analyse a sample of 69 QSOs which have been randomly selected in a complete sample of 104 QSOs (R<18, 0.142 < z < 0.198). 60 have been observed with the NTT/SUSI2 at La Silla, through two filters in the optical band (WB#655 and V#812), and the remaining 9 are taken from archive databases. The filter V#812 contains the redshifted Hbeta and forbidden [OIII] emission lines, while WB#655 covers a spectral region devoid of emission lines, thus measuring the QSO and stellar continua. The contributions of the QSO and the host are separated thanks to the MCS deconvolution algorithm, allowing a morphological classification of the host, and the computation of several parameters such as the host and nucleus absolute V-magnitude, distance between the luminosity center of the host and the QSO, and colour of the host and nucleus. We define a new asymmetry coefficient, independent of any galaxy models and well suited for QSO host studies. The main results from this study are: (i) 25% of the total number of QSO hosts are spirals, 51% are ellipticals and 60% show signs of interaction; (ii) Highly asymmetric systems tend to have a higher gas ionization level (iii) Elliptical hosts contain a substantial amount of ionized gas, and some show off-nuclear activity. These results agree with hierarchical models merger driven evolution.
We present results from a new 100-ks Suzaku observation of the nearby radio galaxy 3C 33, and investigate the nature of absorption, reflection, and jet production in this source. We model the 2-70 keV nuclear continuum with a power law that is absorbed either through one or more layers of pc-scale neutral material, or through a modestly ionized pc-scale obscurer. The expected signatures of reflection from a neutral accretion disk are absent in 3C 33: there is no evidence of a relativistically blurred Fe K$alpha$ emission line, and no Compton reflection hump above 10 keV. We discuss the implications of this for the nature of jet production in 3C 33.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
