[AGORA-mailing-list] Very Sad News: Passing of Avishai Dekel

[Santi Roca Fabrega]

Dear AGORA Colleagues,

It is with profound sorrow that I write to inform you of the passing of Avishai Dekel.

Avishai was a big contributor of our AGORA collaboration from its earliest days. His deep expertise in astrophysics and cosmology shaped much of our scientific direction toghether with Joel who left us just a few days ago.

Among many others, over the years, he made fundamental contributions to our understanding of galaxy formation, the large-scale structure of the universe, dark matter halos, and cosmic flows. In AGORA, he supported us not only with his scientific insight, but also with generous mentorship of PhD students and post-docs, constructive criticism, and a commitment to advancing our shared goals.

His death leaves a great void in our community, and his legacy will continue to inspire our work. Please feel free to share with all of us texts, memories, or thoughts on how Avishai impacted your science and life.

We share with you below the message sent by the former Avishai’s students and post-docs that includes information about the funerals and Shiva.

On behalf of the AGORA community, Ji-hoon and myself extend heartfelt condolences to his family, friends, and all who worked closely with him. His wisdom, kindness, and scientific vision enriched us all, and we are privileged to have had him among us.

Thank you for reading this, and for joining me in honoring his memory. May his memory be a blessing.

Best,

Ji-hoon and Santi

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Dear friends and colleagues,

It is with profound sadness that we bring more heartbreaking news to our community.  Avishai Dekel, Professor of Physics at the Hebrew University of Jerusalem has left us.  He passed peacefully in the night at home surrounded by family.

Avishai was not only a giant in astrophysics, he was also a giant presence in his personal life and in the lives of those around him.  He leaves a gaping hole in the field and in our hearts which cannot be filled.  Avishai was known for his contributions to cosmology and galaxy formation, including highly cited papers on the influence of supernovae on galaxy evolution, fundamental cosmological parameters, the feeding of galaxies via "cold streams" of cosmic gas, the "compaction" of galaxies, "violent disk instabilities" and "feedback-free starbursts" in the early Universe.  These terms which Avishai coined are now part of the general lexicon in the field of galaxy formation and evolution.  Avishai, always curious and passionate about his work, was active until the end, with his latest paper submitted to the Astrophysical Journal only days before he passed:https://arxiv.org/abs/2511.07578

Avishai has been awarded numerous honours including the Landau Prize for Arts and Sciences, Visiting Miller Professorship, Blaise Pascal International Chair of Research, the Lagrange Fellowship, and being named a fellow of the Israel Physics Society.

Besides his publications, Avishai has had a profound impact through his mentorship of many students and postdoctoral researchers who are now successful scientists all around the world.  I believe I can speak for all of us to say that we would not be who we are today without him.

Avishai's funeral will take place on Tuesday Nov 18, 2025 at 12:00 Israel time at the Old Cemetery in Herzliya on Pinsker St.  As is Israeli/Jewish custom, the family will observe seven days of mourning, called "shiva", immediately afterwards at the family home on 15 Nahum St, Ramat Gan.  For those unfamiliar with the custom, shiva is a time when the family home is open to friends and family to come and share food and memories of the deceased, and is a powerful time of healing for the family.  Visitors traditionally bring food, since the family does not cook during this time.

Shiva hours at 15 Nahum St, in Ramat Gan:
Tuesday 16:00-21:00
Wednesday and Thursday 10:00-14:00, 16:00-21:00
Friday 10:00-14:00
Saturday evening 19:00-22:00

Please feel free to pass this news to anyone who would be interested.

As we say in Hebrew, may his memory be a blessing.
Joanna Woo, for Avishai's former students and postdocs.
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