(Reuters) -A federal judge formally sentenced Robert Bowers to death on Thursday for killing 11 worshippers at Pittsburgh's Tree of Life synagogue in 2018, the deadliest antisemitic attack in U.S. history.

The sentencing hearing came a day after a jury unanimously voted for the death penalty after finding Bowers guilty on 63 counts, including 11 counts of obstruction of free exercise of religious beliefs resulting in death.

Survivors of the shooting and relatives of Bowers' victims addressed Judge Robert Colville during the hearing at the U.S. District Court in Pittsburgh in western Pennsylvania. The judge was bound by the jury's decision.

"That I am alive today is a miracle for which I am grateful every morning," Dan Leger, who was badly wounded in the attack, said in court, the Pittsburgh Post-Gazette reported. "And yet every day I live wishing that I had been able to stop this from happening."

The jury also convicted Bowers on more than two dozen non-capital crimes, for which Colville sentenced him to life in prison without the possibility of release.

Before handing down the sentence, Colville noted that judges typically address the offender.

"Frankly I have nothing specific that I care to say directly to Mr. Bowers," the judge said, according to the Post-Gazette. "I mean no particular offense. I am convinced that there is nothing I could say to him that might be meaningful."

Prosecutors successfully argued during the trial that Bowers showed no remorse for his attack on the synagogue during Sabbath morning services.

His defense lawyers did not dispute that Bowers planned and carried out the attack, in which he combed through the building shooting everyone he found with a semiautomatic rifle and three pistols.

Bowers' lawyers unsuccessfully argued that he suffered from life-long mental illness and was delusional and so the jury should spare him from the death penalty and instead sentence him to life in prison without release.

The 12 jurors heard testimony from some of the survivors of the attack and were shown pictures of the carnage and evidence of Bowers' antisemitism, including multiple posts attacking Jews made on a far-right website in the months leading up to the attack.

It is not clear when, if ever, Bowers will be executed: the U.S. Department of Justice has instated a moratorium on carrying out federal executions while it reviews the death penalty, which Biden pledged to abolish when he was running for the presidency.

Bowers will join the 41 other men on federal death row, held in cells near the U.S. government's execution chamber in Terre Haute, Indiana.

(Reporting by Jonathan Allen in New York; Editing by Daniel Wallis and Conor Humphries)