gossip/rumor mill 谣言工厂

You can refer to the people in a particular place or profession who spread gossip as the gossip mill or rumor mill, which is considered as a source of unofficial and unreliable information.

某地或从事某种职业、专事传播各类八卦消息的人，可以称之为gossip mill或rumor mill，即“谣言工厂”，同时也是各种非官方和不可靠消息的集散地。

For example:

Many of these gossips centred around Gosling, whose continued absence only served to fuel the rumour mill.

很多八卦都跟Gosling有关，而他一直不现身更是助长了各种谣言。