In this paper we investigate limits on the iDM sce- nario by considering the temperature and luminosity of recently observed WDs in our closest globular cluster M4. Throughout we assume that the DM annihilates to stan- dard model particles. White dwarves are compact objects made up of a de- generate electron core comprised almost entirely of car- bon and oxygen. The electron degeneracy prevents any contraction and the temperature of this core is too low to ignite nuclear fusion reactions. As a result, WDs have no internal energy source and release only the thermal energy of the non-degenerate ions in the core. For these reasons the evolution of WDs can be described as a cool- ing process and the age of a globular cluster such as M4 can be estimated by observing a cut-off at low magni- tudes in the WD cooling sequence. This has motivated observations of WDs in globular clusters down to very low magnitudes. Recently this low magnitude cut-off has been observed in the globular cluster M4 [15]. We use the best-measured set of data from these observations, subject to all of the selection processes detailed in [15], including the use of proper motion measurements, to produce a decontami- nated sample. We take the data in the form of magnitudes in the F606W and F775W Hubble Space Telescope filters and convert the colour m$_{606}$$_{W}$ − m$_{775}$$_{W}$ to an effective tem- perature under the assumption that the WD is radiat- ing as a black-body. To do this we numerically shine a black-body spectrum through the HST filter transmission curves, convert magnitudes to the ACS/WFC Vega-mag system [16] and correct for reddening and extinction as detailed in Section 9 of [15]. We then use the m$_{606}$$_{W}$ magnitude, the M4 distance modulus, and the effective temperature of each star and compare with Vega [53] to calculate the luminosity for each star. This data is plot- ted in Fig. 4. Having obtained the luminosity and temperature it is possible to calculate the radius of each WD (under the assumption of black-body radiation). Then, using the Salpeter equation of state [17], we calculate an approxi- mate mass-radius relationship, which can be used to de- termine an approximate mass for each star. In Fig. 5 we show the stars in the mass-luminosity plane. In order to set limits on the iDM-nucleon cross-section it is necessary to estimate the DM density surrounding the WD’s at the center of M4. Although it is currently impossible to do this to with any great accuracy, recent developments in the observation and simulated evolution of globular clusters embedded in galactic halos now allow 2 an estimate of the DM content. Some time ago Peebles [18] suggested that globular clusters may be formed in subhalos of DM before falling into galactic halos. How- ever observations of order ∼ 1 mass-to-light ratios [19] and the tidal stripping of stars from some globular clus- ters [54] suggest a significant DM component cannot re- side within or without the observed stellar distribution [20]. These observations set an upper limit on the DM content of globular clusters. Recent simulations have shed light on how these results can be reconciled with a primordial scenario of globular cluster formation through the process of tidal stripping. In fact, the presence of globular clusters has been sug- gested as a clue towards a resolution of the ‘missing satel- lite problem’ of cold DM simulations [21]. In [22] it was found that once a sub-halo falls into a larger halo mass- loss occurs continually through tidal stripping and the or- bit of the sub-halo decays down towards the centre of the larger halo. Further it was found that the mass-loss can be significant, resulting in only ∼ 2% (8%) of the mass of a sub-halo accreted at z = 2 (1) surviving, and this re- sult appears to be independent of the masses of the halo and subhalo. The tidal stripping of DM from primor- dial globular clusters has been investigated with several N-body simulations (see e.g. [23–26]). Results suggest that globular clusters can be formed naturally within DM subhalos which are subsequently tidally stripped by the host galaxy, resulting in a baryon-dominated core with a small mass-to-light ratio, resembling observed globular clusters. In particular a recent analysis of the Aquar- ius simulation [26] lends support to this scenario, and an approximate relation between the current mass of a globular cluster and the mass of the initial subhalo it was embedded within is given as M$_{GC}$ = 0 . 0038 M$_{DM,}$$_{0}$ . A recent review [27] also argues that metal-poor glob- ular clusters formed in low-mass DM halos in the early universe. The observed cold WDs reside in the dense core of M4, which has survived previous tidal stripping until now. Therefore it is reasonable to assume that the majority of the DM in the core of M4, well within the tidal ra- dius, will also have survived from the early subhalo. This assumption is supported by the results of [23] where it is found that the presence of the stellar core makes the subhalos more resilient to tidal stripping, and for NFW subhalo profiles the DM density in the innermost regions of the subhalo is not modified by the external tidal field. Outside of the star dominated region the DM subhalo is stripped back to the tidal radius, thus resulting in a mass-to-light ratio close to the purely baryonic value. Similar reasoning has led to recent consideration of in- direct DM signals from DM annihilation in other globu- lar clusters, [28] and the VERITAS collaboration argue that the association of globular clusters and DM halos fits naturally into the standard paradigm of hierarchical structure formation [29]. Motivated by these developments we follow similar methods to those used in [2], to which we refer the III. DARK MATTER IN M4 II. WHITE DWARVES IN M4