Zobrazeno 1 - 10
of 75
pro vyhledávání: '"Ulvestad, James S."'
Autor:
Ulvestad, James S.
We have made sensitive milliarcsecond-resolution radio images of the nearby merger galaxy Arp 299 at four epochs spread over 18 months between 2003 and 2005. The combined data revealed a total of 30 point sources in the two primary merger nuclei. Twe
Externí odkaz:
http://arxiv.org/abs/0909.3534
We have used the Very Large Array (VLA) to search for radio emission from the globular cluster G1 (Mayall-II) in M31. G1 has been reported by Gebhardt et al. to contain an intermediate-mass black hole (IMBH) with a mass of ~2 x 10^4 solar masses. Rad
Externí odkaz:
http://arxiv.org/abs/0704.1458
Autor:
Healey, Stephen E., Romani, Roger W., Taylor, Gregory B., Sadler, Elaine M., Ricci, Roberto, Murphy, Tara, Ulvestad, James S., Winn, Joshua N.
Publikováno v:
Astrophys.J.Suppl.171:61-71,2007
We have assembled an 8.4 GHz survey of bright, flat-spectrum (alpha > -0.5) radio sources with nearly uniform extragalactic (|b|>10 deg) coverage for sources brighter than S_{4.8 GHz} = 65 mJy. The catalog is assembled from existing observations (esp
Externí odkaz:
http://arxiv.org/abs/astro-ph/0702346
Publikováno v:
Astron.J.133:1868-1873,2007
We have used the VLBI High Sensitivity Array (VLBA with VLA, Green Bank Telescope, and Arecibo) to search for young radio supernovae in three nearby Wolf Rayet dwarf galaxies containing Super Star Clusters (SSCs) and signs of extreme star formation i
Externí odkaz:
http://arxiv.org/abs/astro-ph/0701038
Publikováno v:
Astrophys.J.636:56-62,2005
We present 6 cm Very Large Array observations of the Greene & Ho (2004) sample of 19 low-mass active galaxies with high accretion rates. This is one of the only studies of a uniform sample of narrow-line Seyfert 1 (NLS1) galaxies with such high sensi
Externí odkaz:
http://arxiv.org/abs/astro-ph/0509198
Autor:
Ulvestad, James S., Wong, Diane S., Taylor, Gregory B., Gallimore, Jack F., Mundell, Carole G.
Publikováno v:
Astron.J.130:936-944,2005
The Seyfert galaxy NGC 4151 has been imaged at resolution better than 0.1 pc using a VLBI array consisting of the VLBA and three 100m-class telescopes. A flat-spectrum 3-mJy source with a monochromatic radio power of ~10^{37} ergs/s has been detected
Externí odkaz:
http://arxiv.org/abs/astro-ph/0505141
Autor:
Anderson, James M., Ulvestad, James S.
Publikováno v:
Astrophys.J. 627 (2005) 674-700
We have used the VLA to study radio variability among a sample of 18 low luminosity active galactic nuclei (LLAGNs), on time scales of a few hours to 10 days. The goal was to measure or limit the sizes of the LLAGN radio-emitting regions, in order to
Externí odkaz:
http://arxiv.org/abs/astro-ph/0504066
Publikováno v:
Astrophys.J. 621 (2005) 123-129
We have used the Very Long Baseline Array (VLBA) to image five radio-quiet quasars (RQQs) at milliarcsecond resolution, at frequencies between 1.4 and 5 GHz. These quasars have typical total flux densities of a few millijansky at gigahertz frequencie
Externí odkaz:
http://arxiv.org/abs/astro-ph/0411678
Publikováno v:
Astrophys.J. 606 (2004) 853-861
We present new Very Large Array observations at five frequencies, from 1.4 to 22GHz, of the extremely low-metallicity blue compact dwarf SBS0335-052. The radio spectrum shows considerable absorption at 1.49GHz, and a composite thermal+non-thermal slo
Externí odkaz:
http://arxiv.org/abs/astro-ph/0401394
Publikováno v:
Astrophys.J. 603 (2004) 42-50
Six low-luminosity active galactic nuclei have been imaged at multiple frequencies from 1.7--43 GHz (2.3--15 GHz for three of the galaxies) using the Very Long Baseline Array. In spite of dynamic ranges of about 100 in several frequency bands, all si
Externí odkaz:
http://arxiv.org/abs/astro-ph/0311303