We present the mid-infrared ( MIR ) light curves ( LCs ) of a tidal disruption event ( TDE ) candidate in the center of a nearby ultraluminous infrared galaxy ( ULIRG ) F01004-2237 using archival WISE and NEOWISE data from 2010 to 2016 .
At the peak of the optical flare , F01004-2237 was IR quiescent .
About three years later , its MIR fluxes have shown a steady increase , rising by 1.34 and 1.04 mag in 3.4 and 4.6 \mu m up to the end of 2016 .
The host-subtracted MIR peak luminosity is 2 - 3 \times 10 ^ { 44 } erg s ^ { -1 } .
We interpret the MIR LCs as an infrared echo , i.e . dust reprocessed emission of the optical flare .
Fitting the MIR LCs using our dust model , we infer a dust torus of the size of a few parsecs at some inclined angle .
The derived dust temperatures range from 590 - 850 K , and the warm dust mass is \sim 7 M _ { \odot } .
Such a large mass implies that the dust can not be newly formed .
We also derive the UV luminosity of 4 - 11 \times 10 ^ { 44 } erg s ^ { -1 } .
The inferred total IR energy is 1 - 2 \times 10 ^ { 52 } erg , suggesting a large dust covering factor .
Finally , our dust model suggests that the long tail of the optical flare could be due to dust scattering .