Moritz Fischer
@moritzfischer.world
Astrophysicist • Dark Matter
moritzfischer.world
darkium.org
moritzfischer.world
darkium.org
I am delighted to have started this week as a Feodor Lynen Fellow of the Alexander von Humboldt Foundation (@humboldt-foundation.de) at the Donostia International Physics Centre (@dipcehu.bsky.social) in San Sebastián, working in Raúl Angulo's group.
September 5, 2025 at 4:08 PM
I am delighted to have started this week as a Feodor Lynen Fellow of the Alexander von Humboldt Foundation (@humboldt-foundation.de) at the Donostia International Physics Centre (@dipcehu.bsky.social) in San Sebastián, working in Raúl Angulo's group.
Today, I had the pleasure to review the state of the art in simulations of self-interacting dark matter at the SIDM workshop in Valencia.
indico.ific.uv.es/event/7815/
indico.ific.uv.es/event/7815/
Valencia Workshop on the Small-Scale Structure of the Universe and Self-Interacting Dark Matter (9-20 June 2025) · IFIC Indico Server (Indico)
Set in Valencia’s historic center, this workshop will address the outstanding challenges in small-scale structure formation of the Universe, encompassing numerical simulations, semi-analytical modeling, and particle-physics models of dark matter. By leveraging data from current and upcoming observational facilities such as Gaia, JWST, Euclid, Rubin, and Roman, we will explore novel probes of their astrophysical signatures, including but not limited to, strong gravitational lensing, stellar...
indico.ific.uv.es
June 9, 2025 at 8:55 PM
Today, I had the pleasure to review the state of the art in simulations of self-interacting dark matter at the SIDM workshop in Valencia.
indico.ific.uv.es/event/7815/
indico.ific.uv.es/event/7815/
To collapse or not to collapse? A study led by my student Yashraj Patil on the evolution of a self-interacting dark matter halo with two dark matter species.
arxiv.org/abs/2506.06272
arxiv.org/abs/2506.06272
To collapse or not to collapse: Halo evolution with self-interacting dark matter mass segregation
Surprisingly compact substructures in galaxies and galaxy clusters, but also field halos, have been observed by gravitational lensing. They could be difficult to explain with collisionless dark matter...
arxiv.org
June 9, 2025 at 8:52 PM
To collapse or not to collapse? A study led by my student Yashraj Patil on the evolution of a self-interacting dark matter halo with two dark matter species.
arxiv.org/abs/2506.06272
arxiv.org/abs/2506.06272
Paper day! Today we have our latest study on how to accurately simulate gravothermally collapsing dark matter halos on arXiv!
arxiv.org/abs/2506.06269
arxiv.org/abs/2506.06269
Accurately simulating core-collapse self-interacting dark matter halos
The properties of satellite halos provide a promising probe for dark matter (DM) physics. Observations motivate current efforts to explain surprisingly compact DM halos. If DM is not collisionless but...
arxiv.org
June 9, 2025 at 8:47 PM
Paper day! Today we have our latest study on how to accurately simulate gravothermally collapsing dark matter halos on arXiv!
arxiv.org/abs/2506.06269
arxiv.org/abs/2506.06269
Today, we present the first N-body simulations of a self-interacting dark matter spike around a supermassive black hole in our paper led by V. Sabarish. https://arxiv.org/abs/2505.14779
May 22, 2025 at 4:11 PM
Today, we present the first N-body simulations of a self-interacting dark matter spike around a supermassive black hole in our paper led by V. Sabarish. https://arxiv.org/abs/2505.14779
Finally out! Our paper with the first N-body simulations of dark matter-baryon interactions is now on arXiv. arxiv.org/abs/2504.12393
N-body simulations of dark matter-baryon interactions
Dark matter (DM) particles can interact with particles of the Standard Model. Although there exist constraints from direct and indirect detection experiments, the dynamical evolution of astrophysical ...
arxiv.org
April 18, 2025 at 2:20 PM
Finally out! Our paper with the first N-body simulations of dark matter-baryon interactions is now on arXiv. arxiv.org/abs/2504.12393
How can we simulate realistic self-interacting dark matter models with large- and small-angle scattering? Check out the new study led by our student Cenanda Arido! https://arxiv.org/abs/2410.07175
October 10, 2024 at 6:16 AM
How can we simulate realistic self-interacting dark matter models with large- and small-angle scattering? Check out the new study led by our student Cenanda Arido! https://arxiv.org/abs/2410.07175
Delighted to see that the work led by S. Yang with new constraints on velocity-dependent self-interactions of dark matter got accepted! https://arxiv.org/abs/2305.05067
August 22, 2024 at 9:29 PM
Delighted to see that the work led by S. Yang with new constraints on velocity-dependent self-interactions of dark matter got accepted! https://arxiv.org/abs/2305.05067
Happy that our paper on numerical issues in simulations of collapsing self-interacting dark matter halos got accepted. https://arxiv.org/abs/2403.00739
August 13, 2024 at 3:23 PM
Happy that our paper on numerical issues in simulations of collapsing self-interacting dark matter halos got accepted. https://arxiv.org/abs/2403.00739
It was a pleasure to discuss dark matter research at the KITP conference "Cosmic Signals of Dark Matter Physics: New Synergies"! I am happy that my talk about signatures of the angular dependence of dark matter self-interactions is available on YouTube. https://youtu.be/wmtmhLMgSG8
June 7, 2024 at 7:37 PM
It was a pleasure to discuss dark matter research at the KITP conference "Cosmic Signals of Dark Matter Physics: New Synergies"! I am happy that my talk about signatures of the angular dependence of dark matter self-interactions is available on YouTube. https://youtu.be/wmtmhLMgSG8
How does dynamical friction change when dark matter has self-interactions? Learn about it in our new paper by Laura Sagunski and myself. https://arxiv.org/abs/2405.19392
May 31, 2024 at 4:45 PM
How does dynamical friction change when dark matter has self-interactions? Learn about it in our new paper by Laura Sagunski and myself. https://arxiv.org/abs/2405.19392
SIDM can make subhalos in galaxy clusters more compact, but in a different way than one would naively expect, as shown in our study led by A. Ragagnin, using full physics zoom-in simulations. https://arxiv.org/abs/2404.01383
April 3, 2024 at 9:41 AM
SIDM can make subhalos in galaxy clusters more compact, but in a different way than one would naively expect, as shown in our study led by A. Ragagnin, using full physics zoom-in simulations. https://arxiv.org/abs/2404.01383
Just compiled a plot of various constraints on the dark matter self-interaction cross-section for my upcoming talks.
March 22, 2024 at 9:25 AM
Just compiled a plot of various constraints on the dark matter self-interaction cross-section for my upcoming talks.
Two and four weeks ago, two papers appeared on arXiv investigating numerical problems in N-body simulations of collapsing SIDM halos. We join them with our study explaining the causes of energy conservation errors in simulations of the late collapse phase. https://arxiv.org/abs/2403.00739
March 4, 2024 at 8:05 AM
Two and four weeks ago, two papers appeared on arXiv investigating numerical problems in N-body simulations of collapsing SIDM halos. We join them with our study explaining the causes of energy conservation errors in simulations of the late collapse phase. https://arxiv.org/abs/2403.00739
In our second paper today, led by V. Sabarish, we find that the effects of velocity-dependent self-interactions are more pronounced in the late stages of merging galaxy clusters than shortly after the first passage of the clusters through each other. https://arxiv.org/abs/2310.07769
October 13, 2023 at 8:16 AM
In our second paper today, led by V. Sabarish, we find that the effects of velocity-dependent self-interactions are more pronounced in the late stages of merging galaxy clusters than shortly after the first passage of the clusters through each other. https://arxiv.org/abs/2310.07769
Today on arXiv, our qualitative study of velocity-dependent self-interactions. We find that a strong velocity dependence can diversify the halo population regardless of the angular dependence of the scattering. https://arxiv.org/abs/2310.07750
October 13, 2023 at 8:12 AM
Today on arXiv, our qualitative study of velocity-dependent self-interactions. We find that a strong velocity dependence can diversify the halo population regardless of the angular dependence of the scattering. https://arxiv.org/abs/2310.07750
I am honoured to have received the Best Paper Award from the Cluster of Excellence Quantum Universe today. https://www.qu.uni-hamburg.de/research/highlights/23-04-18-fischer.html
April 18, 2023 at 9:48 PM
I am honoured to have received the Best Paper Award from the Cluster of Excellence Quantum Universe today. https://www.qu.uni-hamburg.de/research/highlights/23-04-18-fischer.html
Our new website for our research on self-interacting dark matter is online. Check it out! https://darkium.org
March 23, 2023 at 7:51 AM
Our new website for our research on self-interacting dark matter is online. Check it out! https://darkium.org
Paper day! We have studied the role of the ICM in merging galaxy clusters with SIDM: 1. the presence of the ICM enhances DM-galaxy offset, 2. the position of the shock front combined with the galaxy positions could be an interesting probe of DM. https://arxiv.org/abs/2302.07882
February 17, 2023 at 10:37 PM
Paper day! We have studied the role of the ICM in merging galaxy clusters with SIDM: 1. the presence of the ICM enhances DM-galaxy offset, 2. the position of the shock front combined with the galaxy positions could be an interesting probe of DM. https://arxiv.org/abs/2302.07882