Phil Armitage

Does magnetic field promote or suppress fragmentation in AGN disks? Results from local shearing box simulations with simple cooling Accretion disks in Active Galactic Nuclei (AGN) are predicted to become gravitationally unstable substantially interior to the black hole's sphere of influence, at radii where the disk is simultaneous...

With Navin Tsung and collaborators, we show how magnetic fields can effectively suppress gravitational instability and fragmentation in AGN accretion disks.

arxiv.org/abs/2507.21991

Requirements for Joint Orbital Characterization of Cold Giants and Habitable Worlds with Habitable Worlds Observatory We determine optimal requirements for the joint detection of habitable-zone planets and cold giant planets with the Habitable Worlds Observatory (HWO). Analysis of 164 nearby stars shows that a corona...

A timely paper for #HWO25: is it enough to find Earth-like planets around other nearby stars? No! We need their planetary system contexts. Does life on Earth depend on Jupiter?

@sabinastro.bsky.social led this nice analysis of HWO requirements to detect Earths + Jupiters.

arxiv.org/abs/2507.21443

Monster black hole merger is biggest ever seen Gravitational wave detector LIGO spots fast-spinning ‘forbidden’ black holes that challenge physics models.

Me and hubby discussing the new LIGO discovery of ginormous merging black holes.

Me to 3 yo: Nico, do you like black holes?

3 yo: No, I like YouTube.

Hubby: well, that's kinda a hybrid black/white hole: light comes out but no information 🤣

Happy #NerdyTuesday! 🧪
@philip-armitage.bsky.social

DBNets2.0: simulation-based inference for planet-induced dust substructures in protoplanetary discs Dust substructures in protoplanetary discs can be signatures of embedded young planets whose detection and characterisation would provide a better understanding of planet formation. Traditional techni...

In work led by Alessandro Ruzza, we use a new simulation-based inference approach to estimate masses of disk embedded planets from ALMA data.

arxiv.org/abs/2506.11200

From today’s ethics training I learned that the threshold for a nominal gift in New York State is $15. The temptation to ask about jumbo jets was strong…

Thread on our simulation work on circumplanetary disks, led by @sabinastro.bsky.social with Alexandra Kuznetsova and Yan-Fei Jiang from @flatironinstitute.org. We’re working to understand when such disks form, and what their structure looks like as we zoom in closer to the planet.

You’re being generous: of course I didn’t even consider it overdue at all until a year after the deadline!

😂🤣

For most papers, reviewers are still responding pretty generously to my requests (thanks!).

No doubt though: “routine” results are not communicated as concisely as in the past. It’s become vastly easier to do many analyses, which is good but adds to the review work a lot.

If you too are experiencing mental health issues due to the ongoing shitshow, please DM me or Signal me at ziadadina.19, I am trying to build a community to help each other.

Y'all, please repost and help me out, this is serious stuff

Planet formation theory: an overview The standard model for planet formation is a bottom-up process in which the origin of rocky and gaseous planets can be traced back to the collision of micron-sized dust grains within the gas-rich envi...

Revised version of a new, short (-ish!) review on planet formation theory:

arxiv.org/abs/2412.11064

Disc-planet misalignment from an unstable triple system: IRAS04125 The IRAS01425+2902 wide binary system was recently reported to have both a young planet and a puzzling geometric arrangement, where the planet and binary both orbit edge-on, but misaligned by 60 deg t...

New paper, led by the amazing @becastro.bsky.social (with Jeremy Smallwood, Andrew Winter, @astrohoss.bsky.social, and others). In which we try to understand the formation of the crazy-looking young planetary system IRAS04125... 🤔 🔭

arxiv.org/abs/2504.07182

Positive Feedback II: How Dust Coagulation inside Vortices Can Form Planetesimals at Low Metallicity The origin of planetesimals ($\sim$100 km planet building blocks) has confounded astronomers for decades, as numerous growth barriers appear to impede their formation. In a recent paper we proposed a ...

Daniel Carrera, Linn Eriksson and collaborators study a “hybrid” mode of planetesimal formation, in which the growth of dust in vortices ultimately drives the system into the collapse regime of streaming instability parameter space.

arxiv.org/abs/2504.06332