Ryan Trainor
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crosstrainor.bsky.social
Ryan Trainor
@crosstrainor.bsky.social
670 followers 330 following 64 posts
astrophysicist / dad / asso. professor at F&M College / visiting scientist “at” JHU / he / him.

interested in galaxies, AGN, data science, and justice.
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crosstrainor.bsky.social
However, the analysis of individual objects shows that we have a few galaxies at low [OIII]/Hb *and* low [NII]/Ha, a region of parameter space that is extremely rare in local galaxies, but which photoionization models predict traces a turnover in [OIII]/Hb toward extremely low O/H (<<10% solar).
An N2-BPT diagram similar to the previous post but with additional points for individual galaxies. CECILIA Faint sources are in pink, and two of the points lie in the lower-left corner, far from the gray points and contours that represent previous large surveys of galaxies. Another N2-BPT diagram, but this one has color-coded points (blue to yellow) from Cloudy photoionization models showing that [OIII]/Hb declines at low Zneb (low O/H, blue points). The CECILIA points in pink trace a range of model points, but the two in the lower left are consistent with O/H < 10% solar.
July 31, 2025 at 4:33 PM
crosstrainor.bsky.social
With that said, we find that the stack and typical galaxy have high [OIII]/Hb and low [NII]/Ha, as expected for low-mass, low-metallicity galaxies (O/H ~ 20% solar, similar to the Trainor+16 Keck/MOSFIRE stack).
An N2-BPT diagram with black axes and a white background showing that the stacked CECILIA Faint spectrum (pink) sits in the upper-left corner, indicating relatively low oxygen abundance compared to local galaxies (dashed lines) and more massive/more luminous galaxies in the early Universe (grey points with error bars).
July 31, 2025 at 4:22 PM
crosstrainor.bsky.social
With that in mind, check out this beautiful spectrum of a single galaxy in 2D and 1D, as well as a stacked 1D spectrum of the 9 objects:
A multi-panel figure showing the spectrum of a single “dwarf” galaxy (NB2929) at 2=2.55. Top panel is the full 2D spectrum, middle panel is the full 1D spectrum, and the lower panel shows inset regions of specific emission lines. The stacked 1D spectrum of 9 faint “dwarf” galaxies at z=2-3. Top panel shows the full spectrum, and inset and lower boxes show zoom-in regions around specific emission lines from H, O, N, and S.
July 31, 2025 at 3:37 PM
crosstrainor.bsky.social
omg a (vicarious) hit bleesk or whatever we call tweets on BlueSky
A screenshot of an Instagram post by Taylor Lorenz that is itself a screenshot of Anna’s post in BlueSky. The instagram post has 3042 likes.
November 30, 2024 at 3:34 PM
crosstrainor.bsky.social
Thanksgiving dinner in Providencia! Everything feels like home (except for the 75 °F weather).
The entrance to El Camino restaurant, with an antique rusty screen and cinderblock walls. In front is a chalkboard reading “Happy Thanksgiving!” Above is a clear blue sky, and to the right is a person with dark hair and a dark red shirt. A white oval dinner plate with turkey, green beans, mashed potatoes, mushrooms, bread, gravy, and cranberry sauce. To the right is a red beverage with ice and a straw and the edge of another full plate. Above is a hand holding a fork. To the left is a menu that says “Thanksgiving Day Celebration at El Camino” and then lists several items in Spanish.
November 28, 2024 at 10:49 PM
crosstrainor.bsky.social
After two months in Santiago, I finally found a bike! I can’t express how excited I am to not have to walk up and down this hill anymore 😅
An orange mountain bike on a balcony is in the center of the frame. In the distant background behind a loose mesh screen is a neighborhood with houses and trees, a hill with an observatory, and the Andes mountains. Walking directions to Cerro Calán from Google Maps, showing an estimated travel time of 38 minutes. Biking directions to Cerro Calán from Google Maps, showing an estimated travel time of 16 minutes.
November 21, 2024 at 12:01 PM
crosstrainor.bsky.social
(And I can’t resist sharing one more photo from Las Campanas Observatory as well, since I’ve been working through a backlog of pictures)
The Milky Way and a small galaxy are in a dark, starry sky. In the foreground is a large silver telescope dome and a road, both illuminated by red light.
November 20, 2024 at 2:21 AM
crosstrainor.bsky.social
I’m here with my family, so we are all trying to continue working on our Spanish, and we are exploring the incredibly diverse natural beauty of Chile as well 😦
Dark mountains and blue lakes under a cloudy sky Sunrise casting diagonal shadows and yellow light on saw-tooth mountain peaks A boat of people wearing orange life jackets approaches a blue iceberg with dark mountains and grey clouds behind them Red-orange light and purple shadows on rolling desert hills
November 20, 2024 at 2:15 AM
crosstrainor.bsky.social
Hey friends, I am emerging from a hole with some life/work/profile updates: I’m currently on sabbatical at the Universidad de Chile, Santiago. You can almost see my office (to the right of the l the telescope dome) in this photo of Cerro Calán!
A green hillside rises above a neighborhood. A telescope dome is on top of the hill. In the background are tall mountains with snow and a blue sky with clouds.
November 19, 2024 at 11:54 PM
crosstrainor.bsky.social
A spooktacular Halloween from my AST101 classroom to yours!
Two men give thumbs up while wearing costumes. The left man wears a blue and purple onesie, and the right man wears a large gray inflatable dinosaur costume.
October 31, 2023 at 11:45 PM