Detections of simultaneous brightening of gamma-ray and optical emissions of a distant blazar GB 1508+5714 at redshift 4.3

Neng-Hui Liao, Shang Li, Zhen-Feng Sheng +1

GB 1508+5714 is a high-redshift blazar ($z$ = 4.3) and a spectrally soft $\gamma$-ray source has been detected in its direction. By analyzing 11.4-yr {\it Fermi}-LAT data, significant l…