We present 5.5 GHz observations with the VLA of a sample of nearby galaxies with energetic nuclear outbursts at mid-infrared (MIR) bands. These observations reach a uniform depth down to a median rms of ~10 uJy, representing one of most sensitive searches for radio emission associated with nuclear transients. We detect radio emission in 12 out of 16 galaxies at a level of >5sigma, corresponding to a detection rate of 75%. Such a high detection is remarkably different from previous similar searches in stellar tidal disruption events. The radio emission is compact and not resolved for the majority of sources on scales of ~<0.5" (<0.9 kpc at z<0.1). We find the possibility of the star-formation contributing to the radio emission is low, but an AGN origin remains a plausible scenario, especially for sources that show evidence of AGN activity in their optical spectra. If the detections could represent radio emission associated with nuclear transient phenomenon such as jet or outflow, we use the blast wave model by analogy with the GRB afterglows to describe the evolution of radio light curves. In this context, the observations are consistent with a decelerating jet with an energy of ~10^{51-52} erg viewed at 30\degree-60\degree off-axis at later times, suggesting that powerful jets may be ubiquitous among MIR-burst galaxies. Future continuous monitoring observations will be crucial to decipher the origin of radio emission through detections of potential flux and spectral evolution. Our results highlight the importance of radio observations to constrain the nature of nuclear MIR outbursts in galaxies.
Radio and X-ray flux rebrightening six years after outburst in a partially-obscured extreme changing-look AGN
Anhui Normal University(安徽师范大学);University of Science and Technology of China(中国科学技术大学);Nanjing Normal University(南京师范大学);National Astronomical Observatories, Chinese Academy of Sciences(中国科学院国家天文台)
A MeerKAT survey of nearby dwarf novae: I. New detections
Radboud University(拉德堡德大学);University of Cape Town(开普敦大学);South African Astronomical Observatory(南非天文台);Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester(曼彻斯特大学物理与天文学学院乔德雷尔银行天体物理学中心);University of Oxford(牛津大学);Rhodes University(罗德岛大学);South African Radio Astronomy Observatory(南非射电天文台);University of Warwick(华威大学);University of Southampton(南安普顿大学)
Probing the potential high-energy messengers of the anticipated T Coronae Borealis outburst
INAF - Osservatorio Astronomico di Palermo(意大利国家天体物理研究所巴勒莫天文台);Institute for Applied Problems in Mechanics and Mathematics, National Academy of Sciences of Ukraine(乌克兰国家科学院应用力学与数学问题研究所);Center for Data Intensive and Time Domain Astronomy, Department of Physics and Astronomy, Michigan State University(密歇根州立大学物理与天文学系数据密集型时域天文中心);Dipartimento di Fisica e Chimica E. Segrè, Università degli Studi di Palermo(巴勒莫大学E. Segre物理化学系)
Constraining the Diffusion Coefficient with HAWC TeV Gamma-Ray Observations of Two Nearby Pulsar Wind Nebulae
附近的电子/正电子加速器,主要是脉冲星风星云(PWNe),被认为是超过10 GeV的正电子过剩的潜在来源。HAWC天文台揭示了两个非常扩展的源,它们在空间上与附近的两个中年恒星重合:Geminga和PSR B 0656 +14,这表明超相对论电子/正电子在我们的后院加速。对这两种PWNe的形态学研究提供了在HAWC能量下扩散系数的约束。在这张海报中,我们将介绍这些PWNe的模型开发和形态学研究,以及最适合数据的衍生扩散系数。