Research
My work as an astronomy researcher mainly focused on the physics of the atomic phase of the interstellar medium. We have primarily conducted HI emission and absorption studies to explore the processes leading up to the formation of molecular clouds, the sites of star formation.
My research interests involve atomic and molecular cloud formation, filaments, high-mass star formation, and magnetic fields
and generally data science, machine learning systems, and artificial intelligence (AI), particularly in the realm of AI safety.
Research projects
HI filaments
Here we present one particular filament of atomic hydrogen (HI) that stands out because of its mere size. "Maggie", named after el Río Magdalena, the largest river in Colombia, is a largely atomic elongated gas cloud that has a mass of more than half a million solar masses.
While in recent years astronomers have studied many molecular filaments and clouds, the sites of star formation, Maggie shows only little detection of molecular gas. Given its length of ≈1200 pc (~3900 light years), Maggie is the largest coherent object in the Milky Way that we know of. Maggie's formation history and whether it is an anomaly or an object of regular occurrence is still not understood.
By clicking on the image on the right you can get an interactive 3D (position-position-velocity) view on Maggie! The colored volume render shows the distribution of the atomic hydrogen gas. The red curve marks the modelled spine of the filament.
Check out the paper here and the accompanying press release here!
THOR
The HI/OH Recombination line survey of the inner Milky Way (THOR; Beuther et al. 2016, Wang et al. 2020a) is a large survey of the inner Galactic plane. The program includes observations of the HI 21cm line, four OH lines, 19 radio recombination lines, and the continuum emission between 1 and 2 GHz. The THOR observations cover the inner portion of the Milky Way's midplane at Galactic longitudes between 17 and 67 degrees and Galactic latitudes between -1.25 and +1.25 degrees.
My work mainly relies on the atomic hydrogen (HI) data. The HI data have an angular resolution of 40″ (i.e. we can resolve angles that are just 2% of the Moon's diameter in the sky!). To see what the THOR-HI observations look like, check out this beautiful rendition by one of our collaborators. After zooming into the coverage of the THOR survey, the video shows the atomic hydrogen emission as the view moves along the Galactic longitude axis. At the same time, it moves back and forth through the entire spectral range of the data.
HI self-absorption (HISA)
HI self-absorption, also referred to as "HISA", occurs when a cold gas cloud of atomic hydrogen (HI) is located in front of a warmer HI cloud along our line of sight. We therefore observe the cold cloud in absorption against the warmer emission background. By measuring HISA, we can disentangle individual cold HI clouds from the otherwise ubiquitous HI gas that creates "messy" spectra, mostly due to the Galactic rotation. Figure 1 shows an example spectrum of the HI emission toward the inner Galactic plane at a Galactic longitude of ℓ≈20°.
Using first and second order polynomial fits to the baselines of the absorption features (red dashed), we can isolate
HISA spectra (red). We use molecular line tracers, such as 13CO (blue), to identify molecular clouds. By
correlating molecular line emission with HISA, we can identify cold atomic gas within those star-forming regions.
We conducted an analysis built upon previous case studies that identified HI self-absorption using polynomial baseline fitting. For an unbiased baseline extraction, however, we developed the automated extraction routine astroSABER (as in Self-Absorption Baseline ExtractoR) that uses a supervised machine learning technique to find optimal baselines for self-absorption. In doing so, we can systematically obtain HISA independent of molecular line emission. This may help us understand how molecular clouds form out of the atomic gas phase of the interstellar medium.
Check out the case study here and the paper introducing the new method here!
Temperature and kinematics of massive star-forming clumps
Here I present the research conducted within the scope of my Bachelor thesis. We have investigated the kinematics and temperature of two high-mass gas clumps using ammonia observations. Ammonia (NH3) is a suitable molecule to trace very cold (T ~ 20 K) and dense (n >104 cm-3) gas. By observing different metastable lines of the NH3 hyperfine structure, which are well detectable with radio telescopes (wavelength λ≈1.3 cm), we can determine the underlying kinematics and temperature of the clumps.
Publications
[publisher, arXiv]
2023, Astronomy & Astrophysics, 679, A130
2023, conference proceedings, Physics and Chemistry of Star Formation
2022, Astronomy & Astrophysics, 657, A1
2020, Astronomy & Astrophysics, 642, A68
2023, The Astronomical Journal, 165, 149
2022, Monthly Notices of the Royal Astronomical Society, 517, 5063
2022, The Astrophysical Journal, 939, 92
2022, Monthly Notices of the Royal Astronomical Society, 512, 4765
2022, Astronomy & Astrophysics, 657, A3
2021, Astronomy & Astrophysics, 651, L4
2021, Astronomy & Astrophysics, 649, A113
2020, Astronomy & Astrophysics, 642, A163
- "Cold atomic hydrogen in the Milky Way",
Harvard-Heidelberg Star Formation Workshop, Cambridge, MA, USA, 2023 - "The atomic phase of the Galactic ISM: a zoom-out",
EDEN Science Workshop, Germany/USA/Taiwan (online), 2023 - "Constraining the properties of the atomic ISM by means of HI emission and absorption studies",
SMA Seminar, CfA, Harvard&Smithsonian, Cambridge, MA, USA, 2022 - "Studying the atomic ISM by means of HI emission",
Center for Computational Astrophysics, New York City, NY, USA, 2022 - "The Galactic dynamics revealed by the filamentary structure in the atomic and molecular emission",
The Early Phase of Star Formation, Schloss Ringberg, Germany, 2022 - "How does the atomic ISM affect molecular cloud formation...?",
Ringberg Meeting: Puzzles of Star Formation, Schloss Ringberg, Germany, 2021 - "The Maggie filament: Physical properties of a giant atomic cloud",
ISM 2021 – Structure, characteristic scales, and star formation, online conference, 2021 - "The Maggie filament: dynamic signatures of a giant atomic cloud",
Heidelberg-Harvard Physics of Star Formation, online conference, 2020
Jonas Syed (he/him)
Contact
Jonas Syed, Dr. rer. nat.
syed [at] mpia.de | |
https://www.researchgate.net/profile/Jonas-Syed | |
https://www.linkedin.com/in/jonassyed | |
https://github.com/astrojoni89 | |
https://orcid.org/0000-0003-4322-8120 |
Königstuhl 17
69117 Heidelberg
GERMANY