Medium-band Observation of the Neutrino Emitting Blazar, TXS 0506+056 Academic Article uri icon


  • Abstract TXS 0506+056 is a blazar that has been recently identified as the counterpart of the neutrino event IceCube-170922A. Understanding the blazar type of TXS 0506+056 is important to constrain the neutrino emission mechanism, but the blazar nature of TXS 0506+056 is still uncertain. As an attempt to understand the nature of TXS 0506+056, we report the medium-band observation results of TXS 0506+056, covering the wavelength range of 0.5751.025 m. The use of the medium-band filters allows us to examine if there were any significant changes in its spectral shapes over the course of one month and give a better constraint on the peak frequency of synchrotron radiation with quasi-simultaneous data sets. The peak frequency is found to be 1014.28 Hz, and our analysis shows that TXS 0506+056 is not an outlier from the blazar sequence. As a way to determine the blazar type, we also analyzed if TXS 0506+056 is bluer-when-brighter (BL Lac type and some flat spectrum radio quasars, FSRQs) or redder-when-brighter (found only in some FSRQs). Even though we detect no significant variability in the spectral shape larger than observational error during our medium-band observation period, the comparison with a data set taken in 2012 shows a possible redder-when-brighter behavior of FSRQs. Our results demonstrate that medium-band observations with small to moderate-sized telescopes can be an effective way to trace the spectral evolution of transients such as TXS 0506+056.

published proceedings


altmetric score

  • 15.08

author list (cited authors)

  • Hwang, S., Im, M., Taak, Y. C., Paek, I., Choi, C., Shin, S., ... Prochaska, T.

citation count

  • 2

complete list of authors

  • Hwang, Sungyong||Im, Myungshin||Taak, Yoon Chan||Paek, Insu||Choi, Changsu||Shin, Suhyun||Lee, Sang-Yun||Ji, Tae-Geun||Pak, Soojong||Lee, Hye-In||Ahn, Hojae||Han, Jimin||Kim, Changgon||Marshall, Jennifer||Johns-Krull, Christopher M||Gibson, Coyne A||Schmidt, Luke||Prochaska, Travis

publication date

  • February 2021