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We calculate the emission line spectrum produced by the debris released whena white dwarf (WD) is tidally disrupted by an intermediate-mass black hole(IMBH; $M\sim 10^{2}-10^{5}\msun$) and we explore the possibility of using theemission lines to identify such events and constrain the properties of theIMBH. To this end, we adopt and adapt the techniques developed by Strubbe &Quataert to study the optical emission lines produced when a main sequence (MS)star is tidally disrupted by a supermassive black hole. WDs are tidallydisrupted outside of the event horizon of a $< 10^{5}\msun$ black hole, whichmakes these tidal disruption events good signposts of IMBHs. We focus on theoptical and UV emission lines produced when the accretion flare photoionizesthe stream of debris that remains unbound during the disruption. We find thatthe spectrum is dominated by lines due to ions of C and O, the strongest ofwhich are \ion{C}{4} $\lambda$1549 at early times and [\ion{O}{3}]$\lambda$5007 at later times. Furthermore, we model the profile of the emissionlines in the [\ion{O}{3}] $\lambda\lambda$4959, 5007 doublet and find that itis highly asymmetric with velocity widths of up to $\sim 2500\rm{\;km\;s^{-1}}$, depending on the properties of the WD-IMBH system and theorientation of the observer. Finally, we compare the models with observationsof X-ray flares and optical emission lines in the cores of globular clustersand propose how future observations can test if these features are due to a WDthat has been tidally disrupted by an IMBH.

Probing Intermediate Mass Black Holes With Optical Emission Lines from Tidally Disrupted White Dwarfs