How to call this : some dots in volcano plot aligned a line after add a very small value to padj

when I plotting the volcano plot, I got some dots very top of the Y-axis because their padj nearly reached 0（I checked the data, I think they are reliable）, so I followed the advice to add a very small value to padj(machine$double.xmin), but still got those dots formed a line. I think I heard these lines have a name like Texas arm(?) or Tech arm(?) something before, but I can’t remember. Can someone tell me what’s the name?
Please help me. here is the plot :