Sophia Gad-NasrAkaun disahkan

@Astropartigirl

I do cosmology and astroparticle theory. I pick apart the Universe to figure out how it works. Science Advisor. UCI PhysSci Scicomm Fellow. 🇵🇱✡🇪🇬☪️ She/her

 |Los Angeles〉+  |Irvine〉
astropartigirl.com
Lihat siaran Tonton SIARAN LANGSUNG
Menyertai Mei 2010
4,450 Foto atau video 4,450 Foto dan video Foto dan video

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  1. Tweet Dipinkan
    21 Feb

    Who wants to hear about dark matter? YOU do, because IT'S AWESOME! Here, I talk about dark matter and my research with excitement, because I love this stuff!

    5:12
    What is dark matter? Today on , we’re getting an in-depth look at what exactly it is with science advisor and cosmology PhD student Sophia Gad-Nasr (aka )!
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  2. Mengetweet Semula
    21 jam lalu

    This is mind-boggling, but also excellently mind expanding stuff! Read it! 🤗 Fantastic work by and colleagues 👏👏

    Everyone: MY FIRST PAPER EVER IS OUT!! This research has been pivotal to my direction in academia. I got to work with and learn from some of the most brilliant physicists, including ! And YES IT'S ABOUT DARK MATTER!! Wanna know more? Thread!
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  3. Mengetweet Semula
    21 jam lalu

    Shedding light on .

    To set the stage for why this research is so significant, a little background on dark matter and what Cold Dark Matter (CDM) and Self-interacting Dark Matter (SIDM) are is warranted, and I have just that for you in a Moment I wrote:
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  4. Mengetweet Semula
    22 jam lalu

    One of my favourite scicomm physicists with a truly fascinating piece of research 😍

    Everyone: MY FIRST PAPER EVER IS OUT!! This research has been pivotal to my direction in academia. I got to work with and learn from some of the most brilliant physicists, including ! And YES IT'S ABOUT DARK MATTER!! Wanna know more? Thread!
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  5. Mengetweet Semula
    23 jam lalu

    Woo! Congratulations! 🎉🍾

    Everyone: MY FIRST PAPER EVER IS OUT!! This research has been pivotal to my direction in academia. I got to work with and learn from some of the most brilliant physicists, including ! And YES IT'S ABOUT DARK MATTER!! Wanna know more? Thread!
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  6. Mengetweet Semula
    27 Jun

    You deserve this and so much more 🥺💖

    Everyone: MY FIRST PAPER EVER IS OUT!! This research has been pivotal to my direction in academia. I got to work with and learn from some of the most brilliant physicists, including ! And YES IT'S ABOUT DARK MATTER!! Wanna know more? Thread!
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  7. Mengetweet Semula
    27 Jun

    New research from our very own grad student and Scicomm Fellow, Sophia Gad-Nasr (second author of the paper) and colleagues. She breaks down the big picture, here:

    Everyone: MY FIRST PAPER EVER IS OUT!! This research has been pivotal to my direction in academia. I got to work with and learn from some of the most brilliant physicists, including ! And YES IT'S ABOUT DARK MATTER!! Wanna know more? Thread!
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  8. Mengetweet Semula
    27 Jun

    Sophia Gad-Nasr gives an overview of what self-interacting dark matter (SIDM) is, and why a velocity dependent version of it better fits observations than other dark matter models in this thread describing her first published paper.

    Everyone: MY FIRST PAPER EVER IS OUT!! This research has been pivotal to my direction in academia. I got to work with and learn from some of the most brilliant physicists, including ! And YES IT'S ABOUT DARK MATTER!! Wanna know more? Thread!
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  9. Mengetweet Semula
    27 Jun

    CONGRATULATIONS!🍾🎉🎈🎊

    Everyone: MY FIRST PAPER EVER IS OUT!! This research has been pivotal to my direction in academia. I got to work with and learn from some of the most brilliant physicists, including ! And YES IT'S ABOUT DARK MATTER!! Wanna know more? Thread!
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  10. Mengetweet Semula
    27 Jun

    Everyone: MY FIRST PAPER EVER IS OUT!! This research has been pivotal to my direction in academia. I got to work with and learn from some of the most brilliant physicists, including ! And YES IT'S ABOUT DARK MATTER!! Wanna know more? Thread!
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  11. 27 Jun

    And this, my friends, is what nearly 4 years of work has given us. It feels amazing to have been part of finding new constraints for the cross-section for SIDM on new scales, and confirming that the cross-section should have a velocity dependence! Any other questions? Ask me! 🙂

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  12. 27 Jun

    The general takeaway: we constrained the cross-section on cluster scales more robustly, and obtained constraints for group scales for the first time. These results support a velocity-dependent cross-section for SIDM. Bringing back this figure, because it's so beautiful!

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  13. 27 Jun

    The reason we chose the cluster age we did was to remain consistent with the rest of the paper, where we choose an age of 5 Gyr (or 5 billion years), while the simulated cluster might actually be closer to 7 Gyr.

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  14. 27 Jun

    We also tested our modeling on two clusters simulated with SIDM and cross-section of 1 cm²/g to see if we get back a similar cross-section. The results were very close, with 1.1 cm²/g to 1.7 cm²/g. The slight error could be due to us underestimating the age of the simulated halo.

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  15. 27 Jun

    We also find SIDM picks higher concentrations and lower virial masses than expected from the cosmological concentration-mass relation (this is a relation that tells us some properties of a galaxy/cluster). That being said, the relation is for CDM, so it might not work for SIDM.

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  16. 27 Jun

    And our results also tell us that AC increases the cross-section a bit compared to no AC (see the figure below). So our upper limits for the cross-section without and with AC for groups is 0.9 cm²/g and 1.1 cm²/g respectively, and for clusters, 0.28 cm²/g and 0.35 cm²/g.

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  17. 27 Jun

    Our results tell us adiabatic contraction (AC) only matters with small cross-sections. In the figure, we've plotted density profiles for a cluster with CDM(ie NO cross-section), 0.1 cm²/g, and 1 cm²/g. You can see AC only changes the profile significantly for small cross-section.

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  18. 27 Jun

    Something else we explored is a phenomenon called adiabatic contraction: in systems with lots of baryonic mass (stars), the high mass near centers can cause dark matter to contract near the center due to gravity. The result is systems with centers that are denser than expected.

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  19. 27 Jun

    Our work spans system masses of ~10¹³-10¹⁵ M_sun. And our results support a velocity-dependent cross-section for SIDM! This means that SIDM can explain all galaxy scales if its cross-section changes with velocity in such a way that it decreases with increasing velocity.

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  20. 27 Jun

    For the first time, we probed a scale not yet explored in SIDM, one between dwarfs and clusters: galaxy groups. We also reanalyzed clusters and for better constraints on the cross-section. And the result supports a velocity-dependent cross-section!! (check out the figure below)

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  21. 27 Jun

    Other research has derived a function for the velocity dependence of the cross-section using measurements of small scales (like dwarf galaxies) and measurements of large scales (galaxy clusters), but the intermediate region has been assumed and not tested. Our paper changes this!

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