VLBI Observations of the Most Radio-Loud, Narrow-Line Quasar SDSS J094857.3 + 002225

We observed the narrow-line quasar SDSS J094857.3+002225, which is known to have the highest radio loudnessin thenarrow-line Seyfert 1 galaxies(NLS1s), at 1.7–15.4GHz withthe VeryLong BaselineArray (VLBA). This is the first very-long-baseline interferometry (VLBI) investigation of a radio-loud NLS1. We independently discovered (1) very high brightness temperatures from its compactness in a VLBA image and (2) flux variation among the VLBA observation and our other observations with the VLBA and the Very Large Array (VLA). A Doppler factor larger than 2.7–5.5 was required to meet an intrinsic limit of brightness temperature in the rest frame. This is evidence for highly relativistic nonthermal jets in an NLS1. We suggest that the Doppler factor is one of the most important parameters in the determination of the radio loudness of NLS1s. The accretion disk of SDSS J094857.3+002225 is probably in a very high state, rather than the high/soft state, by analogy with X-ray binaries with strong radio outbursts and superluminal jets, such as GRS 1915+105.

[1]  W. Lewin,et al.  Compact stellar X-ray sources , 2006 .

[2]  L. Ho,et al.  The Radio Quiescence of Active Galaxies with High Accretion Rates , 2005, astro-ph/0509198.

[3]  P. Shastri,et al.  Milliarcsec-scale radio structure of a matched sample of Seyfert 1 and Seyfert 2 galaxies ⋆,⋆⋆ , 2004, astro-ph/0406597.

[4]  D. Frail,et al.  The Angular Size and Proper Motion of the Afterglow of GRB 030329 , 2004, astro-ph/0405300.

[5]  H. Falcke,et al.  Motion and properties of nuclear radio components in Seyfert galaxies seen with VLBI , 2004, astro-ph/0402142.

[6]  Eric W. Greisen,et al.  AIPS, the VLA, and the VLBA , 2003 .

[7]  Edward J. Wollack,et al.  First-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters , 2003, astro-ph/0302209.

[8]  Cheng Li,et al.  SDSS J094857.3+002225: A Very Radio Loud, Narrow-Line Quasar with Relativistic Jets? , 2003 .

[9]  Hongyan Zhou,et al.  Properties of Broad Band Continuum of Narrow Line Seyfert 1 Galaxies , 2002 .

[10]  S. Mathur,et al.  Narrow-line Seyfert 1 Galaxies from the Sloan Digital Sky Survey Early Data Release , 2002, astro-ph/0208211.

[11]  T. Boroson.  Black Hole Mass and Eddington Ratio as Drivers for the Observable Properties of Radio-loud and Radio-quiet QSOs , 2001, astro-ph/0109317.

[12]  Andre Heck,et al.  Information Handling in Astronomy - Historical Vistas , 2002 .

[13]  A. Oshlack,et al.  A Very Radio Loud Narrow-Line Seyfert 1: PKS 2004–447 , 2001, astro-ph/0105213.

[14]  M. Matsuoka,et al.  A Rapid X-Ray Flare in the Radio-loud Narrow-Line Quasar PKS 0558–504 , 2001, astro-ph/0102199.

[15]  E. Moran.  Radio Properties of NLS1s , 2000, astro-ph/0005149.

[16]  R. Pogge.  Narrow-line Seyfert 1s: 15 years later , 2000, astro-ph/0005125.

[17]  H. Falcke,et al.  A Major Radio Outburst in III Zw 2 with an Extremely Inverted, Millimeter-peaked Spectrum , 1999, astro-ph/9901375.

[18]  A. Lähteenmäki,et al.  Total Flux Density Variations in Extragalactic Radio Sources. II. Determining the Limiting Brightness Temperature for Synchrotron Sources , 1999 .

[19]  A. Lähteenmäki,et al.  Total Flux Density Variations in Extragalactic Radio Sources. I. Decomposition of Variations into Exponential Flares , 1999 .

[20]  P. Wilkinson,et al.  Interferometer phase calibration sources — II. The region 0° ≤ δB1950≤ +20° , 1998 .

[21]  L. Gurvits,et al.  Sub-Milliarcsecond Imaging of Quasars and Active Galactic Nuclei. IV. Fine-Scale Structure , 2005, astro-ph/0505536.

[22]  T. Kii,et al.  AN X-RAY SURVEY OF QUASARS USING ASCA , 1997 .

[23]  M. Turner,et al.  People, Jobs, and Transportation , 1997 .

[24]  A. Márquez,et al.  Are Coronae Restricted to Venus?: Corona-Like Tectonovolcanic Structures on Earth , 1997 .

[25]  Richard L. White,et al.  The FIRST Survey: Faint Images of the Radio Sky at twenty centimeters , 1995 .

[26]  R. Antonucci,et al.  Radio properties of narrow-lined Seyfert 1 galaxies , 1995 .

[27]  Maarten Schmidt,et al.  The radio structure of radio loud and radio quiet quasars in the Palomar Bright Quasar Survey , 1994 .

[28]  Anthony C. S. Readhead,et al.  Equipartition brightness temperature and the inverse Compton catastrophe , 1994 .

[29]  P. Hewett,et al.  Radio properties of optically selected quasars , 1992 .

[30]  D. Osterbrock,et al.  The spectra of narrow-line Seyfert 1 galaxies , 1985 .

[31]  R. Weymann,et al.  The radio properties of the broad-absorption-line QSOs , 1984 .

[32]  Chinese Journal of Astronomy and Astrophysics , 2022 .