Hua-Gang Song

Xinjiang Astronomical Observatory

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Xiang Liu

Chinese Academy of Sciences

M. Krämer

Max Planck Institute for Radio Astronomy

T. P. Krichbaum

Max Planck Institute for Radio Astronomy

N. Marchili

Istituto di Radioastronomia di Bologna

Meng Yang

Shanghai Tunnel Engineering (China)

Yinyu Liu

Tsinghua University

Zhen Ding

Nanjing University of Posts and Telecommunications

Lars Fuhrmann

Fraunhofer Institute for High Frequency Physics and Radar Techniques

Yuqing Lou

Shanghai Jiao Tong University

Lang Cui

Xinjiang Astronomical Observatory

Cooperative Institutions

Chinese Academy of Sciences

Max Planck Institute for Radio Astronomy

National Astronomical Observatories

Xinjiang Astronomical Observatory

Joint Institute for VLBI ERIC

Center for Astrophysics Harvard & Smithsonian

University of Chinese Academy of Sciences

University College Cork

Kyungpook National University

Sejong University

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Bursty Variations of Jovian 6cm Radio Emissions and Quasi-Periodic Jupiter's Polar Activities

arXiv (Cornell University) (2012)

Yuqing Lou Hua-Gang Song Yinyu Liu Meng Yang

In reference to Jupiter south polar quasi-periodic 40-50 min (QP-40) activities and the model scenario for global QP-40 oscillations of the Jovian inner radiation belt (IRB), we validate relevant predictions and confirmations by amassing empirical evidence from Ulysses, Cassini, Chandra, Galileo, XMM-Newton, and Advanced Composition Explorer for Jupiter north polar QP-40 activities. We report ground 6cm radio observations of Jupiter by Urumqi 25m telescope for synchrotron intensity bursty variations of the Jovian IRB and show their likely correlations with the recurrent arrival of high-speed solar winds at Jupiter.

Jupiter (rocket family)

Galileo (satellite navigation)

10.48550/arxiv.1201.1194

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The long-term and intraday variabilities of the BL Lac object OJ287 at 5 GHz

Lang Cui Hua-Gang Song Xiang Liu

In this paper, we use the databases of the university of Michigan Radio Astronomy Observatory (UMRAO) and the Very Large Array (VLA) at 5.0 GHz to analyze the radio light curve of BL Lac object OJ287 by both the power spectrum method and the structure function method. By analyzing several decades data, we find a new quasi-periodicity of 2.3 ± 0.1 yr in its light curves.We also carried out IntraDay Variability (IDV) observations at 5.0 GHz with the Urumqi 25m radio telescope from late 2006, to study the IDV properties of OJ287. We detected an IDV of 1.9 ± 0.6% on average in the source.We discussed the 2.3 yr quasi-periodic variability and the IDV of OJ287, which are both likely caused by intrinsic activities of the source.

BL Lac object

Source

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A new model for the periodic outbursts of the BL Lac object OJ287

Astrophysics and Space Science (2007)

Weizhao Shi Xiang Liu Hua-Gang Song

BL Lac object

Superluminal motion

Flare

Relativistic beaming

10.1007/s10509-007-9413-z

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Citations (10)

Variability Study of the S5 Sample

Journal of Astrophysics and Astronomy (2014)

M. Krämer Lang Cui Xiang Liu Zhen Ding Hua-Gang Song

Spectral index

Variation (astronomy)

Sample (material)

10.1007/s12036-014-9203-2

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Bursty synchrotron intensity variations of Jovian 6-cm radio emissions and Jupiter’s quasi-periodic polar activities

Monthly Notices of the Royal Astronomical Society Letters (2012)

Yuqing Lou Hua-Gang Song Yinyu Liu Meng Yang

ABSTRACT With reference to Jupiter's south polar quasi-periodic 40–50 min (QP-40) activities and the model scenario for global QP-40 magneto-inertial oscillations of the Jovian inner radiation belt (IRB), we validate relevant predictions and confirmations by amassing empirical evidence from Ulysses, Cassini, Chandra, Galileo, XMM–Newton and the Advanced Composition Explorer for Jupiter's north polar QP-40 activities. We report ground 6-cm radio observations of Jupiter by the Urumqi 25-m telescope for synchrotron intensity bursty variations of the Jovian IRB and show their likely correlations with the recurrent arrival of high-speed solar winds at Jupiter.

Jupiter (rocket family)

10.1111/j.1745-3933.2011.01207.x

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Citations (2)

Radio observations of the first three-months ofFermiAGN at 4.8 GHz

Research in Astronomy and Astrophysics (2012)

Xiang Liu Hua-Gang Song M. Krämer Zhen Ding N. Marchili

Using the Urumqi 25 m radio telescope, sources from the first three months of the Fermi-large area telescope detected active galactic nuclei (AGN) catalog with a declination of > 0° were observed in 2009 at 4.8 GHz. The radio flux density appeared to correlate with the γ-ray intensity. Intra-day variability (IDV) observations were performed in March, April and May 2009 for 42 selected γ-ray bright blazars, and ∼60% of them showed evidence of flux variability at 4.8 GHz during the IDV observations. The IDV detection rate was higher than that in previous flat-spectrum AGN samples. IDV appeared more often in the very long baseline interferometry-core dominant blazars, and the non-IDV blazars showed relatively "steeper" spectral indices than the IDV blazars. Pronounced inter-month variability was also found in two BL Lac objects: J0112+2244 and J0238+1636.

Very-long-baseline interferometry

BL Lac object

10.1088/1674-4527/12/2/003

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Citations (6)

5 GHz Observations of Intraday Variability in AGNs

Chinese Journal of Astronomy and Astrophysics (2006)

Hua-Gang Song Xiang Liu

We present the results of intraday variability observations in compact extragalactic radio sources with the 25 m radio telescope of Urumqi Astronomical Observatory at 5 GHz. In total we have observed 116 flat-spectrum sources, of these, 17 show IDV. We present here a summary table of the results, as well as the light curves and structure functions of a few sources. Either interstellar scintillation or an intrinsic origin could be the cause of the variability in these IDV sources. Further observations over a longer time scale are needed to explain the IDV.

Table (database)

10.1088/1009-9271/6/s2/63

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High resolution studies of the IDV quasar J1128+592

Journal of Physics Conference Series (2010)

K. É. Gabányi N. Marchili T. P. Krichbaum Lars Fuhrmann Xiang Liu

J1128+592 is a compact radio quasar and, as ~ 30% of flat spectrum radio sources, shows fast variations in the cm-wavelength regime on time-scales of an hour to few days. Such phenomenon is often explained by scattering of radio waves in the turbulent, ionized interstellar matter of the Milky Way. Regular monitoring observations of J1128+592 performed by the Effelsberg 100-meter and the Urumqi 25-meter radio telescope during the last four years confirmed this, since a seasonal cycle of the variability time-scale was revealed. This effect is one of the most convincing argument in favor of the interstellar scattering induced fast radio variations in blazars. Multi-epoch, multi-frequency observations made by the Very Long Baseline Array (VLBA) together with the annual modulation model enabled us to determine a lower limit of the distance of the screen responsible for the rapid variability. Additionally, it revealed source-intrinsic-change, which affected the variability pattern.

10.1088/1742-6596/218/1/012013

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Progress of research on AGNs at the Urumqi Observatory

Science China Physics Mechanics and Astronomy (2010)

Lang Cui Hua-Gang Song M. Krämer Xiang Liu T. P. Krichbaum

Very-long-baseline interferometry

10.1007/s11433-010-0063-8

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