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Start Over Author "Paragi, Z" Journal monthly notices of the royal astronomical society
25 results on '"Paragi, Z"'

6. Resolved, expanding jets in the Galactic black hole candidate XTE J1908+094

Author

Rushton, A. P., primary, Miller-Jones, J. C. A., additional, Curran, P. A., additional, Sivakoff, G. R., additional, Rupen, M. P., additional, Paragi, Z., additional, Spencer, R. E., additional, Yang, J., additional, Altamirano, D., additional, Belloni, T., additional, Fender, R. P., additional, Krimm, H. A., additional, Maitra, D., additional, Migliari, S., additional, Russell, D. M., additional, Russell, T. D., additional, Soria, R., additional, and Tudose, V., additional

Published
2017
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8. Revealing H I gas in emission and absorption on pc to kpc scales in a galaxy at z ~ 0.017.

Author

Gupta, N., Srianand, R., Farnes, J. S., Pidopryhora, Y., Vivek, M., Paragi, Z., Noterdaeme, P., Oosterloo, T., and Petitjean, P.

Subjects
H I regions (Astrophysics), EMISSION-line galaxies, QUASARS, ABSORPTION spectra, SPIN temperature
Abstract

We present a detailed study of the quasar-galaxy pair: J1243+4043-UGC 07904. The sight line of the background quasar (zq = 1.5266) passes through a region of the galaxy (zg = 0.0169) at an impact parameter of 6.9 kpc with high metallicity (0.5 Z⊙) and negligible dust extinction. We detect H I 21-cm absorption from the foreground galaxy at arcsecond and milliarcsecond scales. For typical cold neutral medium (CNM) temperatures in the Milky Way, this 21-cm absorber can be classified as a damped Lyα absorber (DLA). We infer the harmonic mean spin temperature of the gas to be ~400K and for a simple two-phase medium we estimate the CNM fraction to be fCNM = 0.27. This is remarkably consistent with the CNM fraction observed in the Galaxy and less than that of high-redshift DLAs. The quasar exhibits a core-jet morphology on milliarcsecond scales, corresponding to an overall extent of ~9 pc at zg. We show that the size of CNM absorbing clouds associated with the foreground galaxy is >5 pc and they may be part of cold gas structures that extend beyond ~35 pc. Interestingly, the rotation measure of quasar J1243+4043 is higher than any other source in samples of quasars with high-z DLAs. However, we do not find any detectable differences in rotation measures and polarization fraction of sight lines with or without high-z (z ≥ 2) DLAs or low-z (z ≤ 0.3) 21-cm absorbers. Finally, the foreground galaxy UGC07904 is also part of a galaxy group. We serendipitously detect H I 21-cm emission from four members of the group, and an ~80 kpc long HI bridge connecting two of the other members. The latter, together with the properties of the group members, suggests that the group is a highly interactive environment. [ABSTRACT FROM AUTHOR]

Published
2018
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9. Multiple AGN in the crowded field of the compact group SDSS J0959+1259

Author

De Rosa, A., primary, Bianchi, S., additional, Bogdanović, T., additional, Decarli, R., additional, Herrero-Illana, R., additional, Husemann, B., additional, Komossa, S., additional, Kun, E., additional, Loiseau, N., additional, Paragi, Z., additional, Perez-Torres, M., additional, Piconcelli, E., additional, Schawinski, K., additional, and Vignali, C., additional

Published
2015
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11. The radio structure of the peculiar narrow-line Seyfert 1 galaxy candidate J1100+4421.

Author

Gabányi, K. É., Frey, S., Paragi, Z., Järvelä, E., Morokuma, T., An, T., Tanaka, M., and Tar, I.

Subjects
ACTIVE galaxies, BL Lacertae objects, BLACK holes, SPECTRAL energy distribution, RADIO sources (Astronomy), COMPACT objects (Astronomy)
Abstract

Narrow-line Seyfert 1 galaxies (NLS1) are an intriguing subclass of active galactic nuclei. Their observed properties indicate low central black hole mass and high accretion rate. The extremely radio-loud NLS1 sources often show relativistic beaming and are usually regarded as younger counterparts of blazars. Recently, the object SDSS J110006.07+442144.3 was reported as a candidate NLS1 source. The characteristics of its dramatic optical flare indicated its jet-related origin. The spectral energy distribution of the object was similar to that of the γ -ray detected radio-loud NLS1, PMNJ0948+0022. Our high-resolution European very long baseline interferometry network observations at 1.7 and 5 GHz revealed a compact core feature with a brightness temperature of ≳1010 K. Using the lowest brightness temperature value and assuming a moderate Lorentz factor of ∼9, the jet viewing angle is ≲26°. Archival Very Large Array data show a large-scale radio structure with a projected linear size of ∼150 kpc reminiscent of double-sided morphology. [ABSTRACT FROM AUTHOR]

Published
2018
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12. A comprehensive radio view of the extremely bright gamma-ray burst 130427A

Author

van der Horst, A. J., primary, Paragi, Z., additional, de Bruyn, A. G., additional, Granot, J., additional, Kouveliotou, C., additional, Wiersema, K., additional, Starling, R. L. C., additional, Curran, P. A., additional, Wijers, R. A. M. J., additional, Rowlinson, A., additional, Anderson, G. A., additional, Fender, R. P., additional, Yang, J., additional, and Strom, R. G., additional

Published
2014
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14. Broad-band monitoring tracing the evolution of the jet and disc in the black hole candidate X-ray binary MAXI J1659−152

Author

van der Horst, A. J., primary, Curran, P. A., additional, Miller-Jones, J. C. A., additional, Linford, J. D., additional, Gorosabel, J., additional, Russell, D. M., additional, de Ugarte Postigo, A., additional, Lundgren, A. A., additional, Taylor, G. B., additional, Maitra, D., additional, Guziy, S., additional, Belloni, T. M., additional, Kouveliotou, C., additional, Jonker, P. G., additional, Kamble, A., additional, Paragi, Z., additional, Homan, J., additional, Kuulkers, E., additional, Granot, J., additional, Altamirano, D., additional, Buxton, M. M., additional, Castro-Tirado, A., additional, Fender, R. P., additional, Garrett, M. A., additional, Gehrels, N., additional, Hartmann, D. H., additional, Kennea, J. A., additional, Krimm, H. A., additional, Mangano, V., additional, Ramirez-Ruiz, E., additional, Romano, P., additional, Wijers, R. A. M. J., additional, Wijnands, R., additional, and Yang, Y. J., additional

Published
2013
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19. A weak compact jet in a soft state of Cygnus X-1

Author

Rushton, A., primary, Miller-Jones, J. C. A., additional, Campana, R., additional, Evangelista, Y., additional, Paragi, Z., additional, Maccarone, T. J., additional, Pooley, G. G., additional, Tudose, V., additional, Fender, R. P., additional, Spencer, R. E., additional, and Dhawan, V., additional

Published
2011
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25. A weak compact jet in a soft state of Cygnus X-1.

Author

Rushton, A., Miller-Jones, J. C. A., Campana, R., Evangelista, Y., Paragi, Z., Maccarone, T. J., Pooley, G. G., Tudose, V., Fender, R. P., Spencer, R. E., and Dhawan, V.

Subjects
JETS (Fluid dynamics), GRENZ rays, ASTRONOMICAL observations, CYGNUS (Constellation), VERY long baseline interferometry, IMAGING systems in astronomy, RADIO astronomy
Abstract

ABSTRACT We present evidence for the presence of a weak compact jet during a soft X-ray state of Cygnus X-1. Very-high-resolution radio observations were taken with the VLBA, EVN and MERLIN during a hard-to-soft spectral state change, showing the hard state jet to be suppressed by a factor of about 3-5 in radio flux and unresolved to direct imaging observations (i.e. ≲1 mas at 4 cm). High time-resolution X-ray observations with the RXTE-PCA were also taken during the radio monitoring period, showing the source to make the transition from the hard state to a softer state (via an intermediate state), although the source may never have reached the canonical soft state. Using astrometric very long baseline interferometry (VLBI) analysis and removing proper motion, parallax and orbital motion signatures, the residual positions show a scatter of ∼0.2 mas (at 4 cm) and ∼3 mas (at 13 cm) along the position angle of the known jet axis; these residuals suggest that there is a weak unresolved outflow, with varying size or opacity, during intermediate and soft X-ray states. Furthermore, no evidence was found for extended knots or shocks forming within the jet during the state transition, suggesting that the change in outflow rate may not be sufficiently high to produce superluminal knots. [ABSTRACT FROM AUTHOR]

Published
2012
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