An Attempt to Probe the Radio Jet Collimation Regions in NGC 4278, NGC 4374 (M84), and NGC 6166
AffiliationUniv Arizona, Steward Observ
galaxies: elliptical and lenticular, cD
galaxies: individual (NGC 4278, NGC 4374, NGC 4486, NGC 6166)
radio continuum: galaxies
MetadataShow full item record
CitationC. Ly et al 2004 AJ 127 119
Rights© 2004. The American Astronomical Society. All rights reserved. Printed in U.S.A.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractNRAO Very Long Baseline Array (VLBA) observations of NGC 4278, NGC 4374 (M84), NGC 6166, and M87 (NGC 4486) have been made at 43 GHz in an effort to image the jet collimation region. This is the first attempt to image the first three sources at 43 GHz using very long baseline interferometry (VLBI) techniques. These three sources were chosen because their estimated black hole mass and distance implied a Schwarzschild radius with large angular size, giving hope that the jet collimation regions could be studied. Phase referencing was utilized for the three sources because of their expected low flux densities. M87 was chosen as the calibrator for NGC 4374 because it satisfied the phase-referencing requirements: near the source and sufficiently strong. Having observed M87 for a long integration time, we have detected its subparsec jet, allowing us to confirm previous high-resolution observations made by Junor, Biretta, & Livio, who have indicated that a wide opening angle was seen near the base of the jet. Phase referencing successfully improved our image sensitivity, yielding detections and providing accurate positions for NGC 4278, NGC 4374, and NGC 6166. These sources are point dominated but show suggestions of extended structure in the direction of the large-scale jets. However, higher sensitivity will be required to study their subparsec jet structure.
VersionFinal published version
Showing items related by title, author, creator and subject.
The Faint End of the Centaurus A Satellite Luminosity FunctionCrnojević, D.; Sand, D. J.; Bennet, P.; Pasetto, S.; Spekkens, K.; Caldwell, N.; Guhathakurta, P.; McLeod, B.; Seth, A.; Simon, J. D.; et al. (IOP PUBLISHING LTD, 2019-02-10)The Panoramic Imaging Survey of Centaurus and Sculptor (PISCeS) is constructing a wide-field map of the resolved stellar populations in the extended halos of these two nearby, prominent galaxies. We present new Magellan/Megacam imaging of a similar to 3 deg(2) area around Centaurus A (Cen A), which filled in much of our coverage to its south, leaving a nearly complete halo map out to a projected radius of similar to 150 kpc and allowing us to identify two new resolved dwarf galaxies. We have additionally obtained deep Hubble Space Telescope (HST) optical imaging of 11 out of the 13 candidate dwarf galaxies identified around Cen A and presented in Crnojevic et al. 2016a: seven are confirmed to be satellites of Cen A, while four are found to be background galaxies. We derive accurate distances, structural parameters, luminosities, and photometric metallicities for the seven candidates confirmed by our HST/ACS imaging. We further study the stellar population along the similar to 60 kpc long (in projection) stream associated with Dw3, which likely had an initial brightness of M-V similar to -15 and shows evidence for a metallicity gradient along its length. Using the total sample of 11 dwarf satellites discovered by the PISCeS survey, as well as 13 brighter previously known satellites of Cen A, we present a revised galaxy luminosity function for the Cen A group down to a limiting magnitude of M-V similar to -8, which has a slope of -1.14 +/- 0.17, comparable to that seen in the Local Group and in other nearby groups of galaxies.
Planck's dusty GEMS III. A massive lensing galaxy with a bottom-heavy stellar initial mass function at z=1.5Canameras, R.; Nesvadba, N. P. H.; Kneissl, R.; Limousin, M.; Gavazzi, R.; Scott, D.; Dole, H.; Frye, B.; Koenig, S.; Le Floc'h, E.; et al. (EDP SCIENCES S A, 2017-03-24)We study the properties of the foreground galaxy of the Ruby, the brightest gravitationally lensed high-redshift galaxy on the sub-millimeter sky as probed by the Planck satellite, and part of our sample of Planck's dusty GEMS. The Ruby consists of an Einstein ring of 1.4" diameter at z = 3.005 observed with ALMA at 0.1" resolution, centered on a faint, red, massive lensing galaxy seen with HST/WFC3, which itself has an exceptionally high redshift, z = 1.525 +/- 0.001, as confirmed with VLT/X-shooter spectroscopy. Here we focus on the properties of the lens and the lensing model obtained with LENSTOOL. The rest-frame optical morphology of this system is strongly dominated by the lens, while the Ruby itself is highly obscured, and contributes less than 10% to the photometry out to the K band. The foreground galaxy has a lensing mass of (3.70 +/- 0.35) x 10(11) M-Theta Magnification factors are between 7 and 38 for individual clumps forming two image families along the Einstein ring. We present a decomposition of the foreground and background sources in the WFC3 images, and stellar population synthesis modeling with a range of star-formation histories for Chabrier and Salpeter initial mass functions (IMFs). Only the stellar mass range obtained with the latter agrees well with the lensing mass. This is consistent with the bottom-heavy IMFs of massive high-redshift galaxies expected from detailed studies of the stellar masses and mass profiles of their low-redshift descendants, and from models of turbulent gas fragmentation. This may be the first direct constraint on the IMF in a lens at z = 1.5, which is not a cluster central galaxy.
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)Majewski, Steven R.; Schiavon, Ricardo P.; Frinchaboy, P. M.; Prieto, Carlos Allende; Barkhouser, Robert; Bizyaev, Dmitry; Blank, Basil; Brunner, Sophia; Burton, Adam; Carrera, R.; et al. (IOP PUBLISHING LTD, 2017-08-14)The Apache Point Observatory Galactic Evolution Experiment (APOGEE), one of the programs in the Sloan Digital Sky Survey III (SDSS-III), has now completed its systematic, homogeneous spectroscopic survey sampling all major populations of the Milky Way. After a three-year observing campaign on the Sloan 2.5 m Telescope, APOGEE has collected a half million high-resolution (R similar to 22,500), high signal-to-noise ratio (>100), infrared (1.51-1.70 mu m) spectra for 146,000 stars, with time series information via repeat visits to most of these stars. This paper describes the motivations for the survey and its overall design-hardware, field placement, target selection, operations-and gives an overview of these aspects as well as the data reduction, analysis, and products. An index is also given to the complement of technical papers that describe various critical survey components in detail. Finally, we discuss the achieved survey performance and illustrate the variety of potential uses of the data products by way of a number of science demonstrations, which span from time series analysis of stellar spectral variations and radial velocity variations from stellar companions, to spatial maps of kinematics, metallicity, and abundance patterns across the Galaxy and as a function of age, to new views of the interstellar medium, the chemistry of star clusters, and the discovery of rare stellar species. As part of SDSS-III Data Release 12 and later releases, all of the APOGEE data products are publicly available.