CEA/DAp seminar organization

The Astrophysics Seminars of the DAp (Département d'Astrophysique) are held at the Orme des Merisiers campus of the CEA Saclay. The schedule is posted on this website. Unless otherwise posted, the seminar takes place at 10am on alternate Tuesdays in room Galilée (Building 713C).

Current seminar organization team: Frédéric GALLIANO, Pierre-Antoine FRUGIER, Virginia AJANI, Matteo BUGLI, Carlos GOMEZ-GUIJARRO, Damien TURPIN.

Main official page for advertising the schedule: http://irfu.cea.fr/dap/Phocea/Vie_des_labos/Seminaires/index.php?type=3










Past seminar and next ones (current date: April 18, 2021)


Tuesday

April 6

10:00
[TBA]

Tuesday

April 20

Vacations / Vacances
Vacances de printemps
Tuesday

April 27

10:00
Frédéric BOURNAUD
(Departement d’Astrophysique, IRFU, CEA-Saclay et Université Paris-Saclay)

Cosmological simulations of galaxy formation: toward a robust accounting of galaxy populations and star formation across the Universe?


[click here for abstract]
Cosmological simulations of galaxy formation are reaching a high level of accuracy and can finely reproduce some of the main properties of galaxy populations: stellar masses, angular momentum, colors, etc. However, most galaxy formation simulations still fail to account for the detailed structure of galaxies and their global star formation history. Using high-resolution, idealized simulations of galactic dynamics and star formation, I will show that these disagreements are not cosmetic details but point toward a fundamental tension between observations and galaxy formation models. Historically, galaxy formation models predicted galaxies with unrealistically large stellar masses: in modern cosmological simulations, this issue is generally solved though energetic feedback from young stars and supermassive black holes. I will nevertheless show that feedback, as implemented in such simulations, is generally excessive, leading to the early and unrealistic exhaustion of interstellar gas reservoirs. Comparisons to idealized simulations and observations of galactic winds support the conclusion that energetic stellar and black hole feedback cannot be entirely responsible for the regulation of star formation and galaxy growth. Other physical processes likely emerge from sub-galactic scales in the interstellar medium, such as subtle coupling between galactic dynamics and star formation through instabilities and turbulence. Nevertheless, some cosmological simulations can now successfully describe the re-distribution of baryons from galaxies to the intergalactic medium, and I will show that these simulations are a crucial tool not just for galaxy formation but also for modern cosmological surveys. I will finally review how simulations of galaxy formation, evolution and star formation could gain strength in the years to come, in relation with the arrival of exascale supercomputers.

Local contact: Carlos GOMEZ-GUIJARRO, organization: Carlos GOMEZ-GUIJARRO






Archives:

          





2021

Tuesday

January 12

10:00
[TBA]
Tuesday

January 26

10:00
[TBA]
Tuesday

February 9

10:00

Salle Virtual seminar
Michelle LOCHNER
(AIMS, South Africa)

Anomaly Detection in Astronomical Data using Machine Learning


[click here for abstract]
The next generation of telescopes such as the SKA and the Vera C. Rubin Observatory will produce enormous data sets, far too large for traditional analysis techniques. Machine learning has proven invaluable in handling large data volumes and automating many tasks traditionally done by human scientists. In this talk, I will discuss how machine learning for anomaly detection can help automate the process of locating unusual astronomical objects in large datasets thus enabling new cosmic discoveries.

Local contact: Virginia AJANI, organization: Virginia AJANI
Tuesday

February 23

Vacations / Vacances
Vacances d'hiver
Tuesday

March 9

10:00
[TBA]
Tuesday

March 23

10:00
[TBA]
Tuesday

April 6

10:00
[TBA]
Tuesday

April 20

Vacations / Vacances
Vacances de printemps
Tuesday

April 27

10:00
Frédéric BOURNAUD
(Departement d’Astrophysique, IRFU, CEA-Saclay et Université Paris-Saclay)

Cosmological simulations of galaxy formation: toward a robust accounting of galaxy populations and star formation across the Universe?


[click here for abstract]
Cosmological simulations of galaxy formation are reaching a high level of accuracy and can finely reproduce some of the main properties of galaxy populations: stellar masses, angular momentum, colors, etc. However, most galaxy formation simulations still fail to account for the detailed structure of galaxies and their global star formation history. Using high-resolution, idealized simulations of galactic dynamics and star formation, I will show that these disagreements are not cosmetic details but point toward a fundamental tension between observations and galaxy formation models. Historically, galaxy formation models predicted galaxies with unrealistically large stellar masses: in modern cosmological simulations, this issue is generally solved though energetic feedback from young stars and supermassive black holes. I will nevertheless show that feedback, as implemented in such simulations, is generally excessive, leading to the early and unrealistic exhaustion of interstellar gas reservoirs. Comparisons to idealized simulations and observations of galactic winds support the conclusion that energetic stellar and black hole feedback cannot be entirely responsible for the regulation of star formation and galaxy growth. Other physical processes likely emerge from sub-galactic scales in the interstellar medium, such as subtle coupling between galactic dynamics and star formation through instabilities and turbulence. Nevertheless, some cosmological simulations can now successfully describe the re-distribution of baryons from galaxies to the intergalactic medium, and I will show that these simulations are a crucial tool not just for galaxy formation but also for modern cosmological surveys. I will finally review how simulations of galaxy formation, evolution and star formation could gain strength in the years to come, in relation with the arrival of exascale supercomputers.

Local contact: Carlos GOMEZ-GUIJARRO, organization: Carlos GOMEZ-GUIJARRO
Tuesday

May 4

10:00
[TBA]
Tuesday

May 18

10:00
[TBA]
Tuesday

June 1

10:00
[TBA]
Tuesday

June 15

10:00
Special event / Evénement exceptionnel
Colloque en l'honneur de C. Cesarsky
(Array)

[TBA]



Local contact: [-], organization: [-]
Tuesday

June 29

10:00
[TBA]





Archives:

          







Seminars in other places:

IAS, IAP, IAP/GRECO, IHES









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