BLACKWELL, Justice.

Dustin James Cotton was tried by a Clayton County jury and convicted of murder and other crimes in connection with the fatal stabbing of Tyriss Turner. Cotton appeals, contending that the verdict is against the weight of the evidence. Cotton also asserts that the trial court erred when it denied his motion for pretrial immunity, when it admitted evidence of incriminating messages that he sent through Facebook, and when it refused his request to charge the jury on defense of others. We see no error, and we affirm.1

1. Viewed in the light most favorable to the verdict, the evidence shows that Cotton had a home in Pennsylvania, but in July 2011, Cotton was living with Turner, Turner's six-year-old daughter, and Cotton's sister (who was also Turner's girlfriend) in Turner's apartment near Jonesboro. On the evening of July 30, Turner and Cotton's sister got into an argument that escalated into a physical altercation. Cotton intervened and fought with Turner in the living room of the apartment. Cotton pushed Turner into a lamp, went into the kitchen, returned to the living room with a knife, and stabbed Turner in the chest in the presence of Turner's young daughter. Cotton then fled the scene and went back to Pennsylvania. Cotton's sister took Turner to the hospital, where Turner later succumbed to his wounds.

Cotton argues that he is entitled to a new trial because the guilty verdict, he says, was against the weight of the evidence. But the discretion to grant a new trial on the basis that the verdict is "decidedly and strongly against the weight of the evidence" is a discretion committed exclusively to the trial court. OCGA § 5-5-21. See also Smith v. State, 292 Ga. 316, 317(1)(b), 737 S.E.2d 677 (2013). As an appellate court, we cannot consider whether the verdict is consistent with the weight of the evidence, and our review is limited instead to the legal sufficiency of the evidence. While Cotton claims that the evidence presented a "textbook" case of self-defense,2 the jury "was free to accept the evidence that the stabbing was not done in self-defense and to reject any evidence in support of a justification defense." Grimes v. State, 293 Ga. 559, 560(1), 748 S.E.2d 441 (2013) (citation and punctuation omitted). Viewing the evidence in the light most favorable to the verdict, as we must, we conclude that the evidence was sufficient to authorize a rational trier of fact to find beyond a reasonable doubt that Cotton was guilty of the crimes of which he was convicted. See Jackson v. Virginia, 443 U.S. 307, 319(III)(B), 99 S.Ct. 2781, 61 L.Ed.2d 560 (1979).

2. Before trial, Cotton filed a motion for immunity from prosecution under OCGA § 16-3-24.2. Following a hearing, the trial court denied Cotton's motion, and Cotton now claims that the trial court employed the wrong standard when it determined that his justification defense was not strong enough to afford him immunity from prosecution. We disagree.

To avoid trial based on a justification defense presented at an immunity hearing, "a defendant bears the burden of showing that he is entitled to immunity under OCGA § 16-3-24.2 by a preponderance of the evidence." Bunn v. State, 284 Ga. 410, 413(3), 667 S.E.2d 605 (2008). Here, Cotton points out that, at the hearing on his immunity motion, the trial judge did not reference the Bunn standard or explicitly say that he had weighed the evidence. The trial judge did say at one point that he found the conflicts in the evidence sufficient to send the case to a jury, and he later clarified that he had weighed the evidence during the immunity hearing and determined not only that Cotton failed to show that he was entitled to immunity by a preponderance of the evidence but that it appeared "more likely than not that [Cotton] was not acting in self-defense [when he killed Turner]" (emphasis supplied). Because the trial court properly weighed the evidence and found that Cotton failed to meet his burden under the standard enunciated in Bunn, id., this enumeration of error has no merit.

3. Cotton also alleges that the trial court erred when it admitted evidence of two incriminating messages that he sent through Facebook.3 In the first message, Cotton wrote that "I KILLED TY AND IT FELT REAL GOOOOOOOOD DOING IT," and in the second message he wrote, "im [sic] happy i killed ty."4 On appeal, Cotton claims that these messages were not properly authenticated.5 But Cotton's only objection to the Facebook messages at trial was that they were "prejudicial and not probative." As a result, Cotton has waived any other claim about the admissibility of the messages. See OCGA § 24-1-103(a)(1); see also Quintanilla v. State, 273 Ga. 20, 21(2), 537 S.E.2d 352 (2000); Sowell v. State, 327 Ga.App. 532, 536(1), 759 S.E.2d 602 (2014) (defendant waived claim that document was not properly authenticated when he failed to make such an objection at trial).

Even if it were otherwise, Cotton's claim about the authentication of the Facebook messages appears to be meritless. We have held that "[d]ocuments from electronic sources such as the printouts from a website like [Facebook] are subject to the same rules of authentication as other more traditional documentary evidence and may be authenticated through circumstantial evidence." Burgess v. State, 292 Ga. 821, 823(4), 742 S.E.2d 464 (2013) (citations and footnote omitted).6 Here, Turner's mother testified that she knew Cotton went by the name "Bucky Raw" because she saw videos that he had posted — and in which he appeared — on YouTube using that alias, because she saw that Cotton's friends and family were Facebook "friends" with "Bucky Raw," and because she was able to discern Cotton's identity through the conversations she had with him on the accounts that she and her friend had set up. As a result, even if Cotton had made an objection to this evidence on authentication grounds, the trial court would not have abused its discretion in overruling it.

4. Finally, Cotton alleges that the trial court erred when it refused his request to charge the jury on defense of others. At trial, both Cotton and Turner's daughter testified that Cotton intervened in the physical altercation between Turner and Cotton's sister. But Cotton also testified that he intervened in order to grab his sister because he "guess[ed] she [was] trying to go after [Turner]." And he explicitly testified that, after he began fighting with Turner, he was worried about his own safety and not his sister's, that Turner wrestled him to the kitchen and away from his sister in the living room, and that he stabbed Turner in order to defend himself and not his sister. This unequivocal testimony showed that Cotton did not kill Turner to protect his sister from an "imminent use of unlawful force" by Turner. OCGA § 16-3-21(a). And because there was no evidence that Cotton killed Turner in defense of his sister (or any other third party), the trial court did not err when it refused to charge the jury on defense of others. See Hicks v. State, 287 Ga. 260, 262(2), 695 S.E.2d 195 (2010).

Judgment affirmed.

All the Justices concur.