Scientific Articles

Click here to see the full publication list on NASA/ADS.

Click here to download the publication list in PDF format.

42. Luo, G.,  Zhang, Z-Y., Bisbas, T.~G., Li, D., Zhou, P., et al., 2023., ApJ, in press. 

Abundance ratios of OH/CO and HCO+/CO as probes of the cosmic ray ionization rate in diffuse clouds


41. Lelli, F., Zhang, Z-Y, Bisbas, T.G., Lin, L., Papadopoulos, P., et al., A&A, in press.

Cold gas disks in main-sequence galaxies at cosmic noon: Low turbulence, flat rotation curves, and disk-halo degeneracy

40. Luo, G., Zhang, Z-Y, Bisbas, T.G., Li, D., Tang, N. et al., 2023, ApJ, 942, 101

Dependence of chemical abundance on the cosmic-ray ionization rate in IC348

39. Bisbas, T.G., van Dishoeck E.F., Hu, C-Y, and Schruba, A., 2023, MNRAS, 519, 729

PDFchem: a new fast method to determine ISM properties and infer environmental parameters using probability distributions 

[Click to visit the code site]

38. Bisbas, T.G., Walch, S., Naab, T., Lahen, N., Herrera-Camus, R. et al. 2022, ApJ, 934, 115

The origin of the [CII] deficit in a simulated dwarf galaxy merger-driven starburst


37. Gaches, B.A.L., Bialy, S., Bisbas, T.G., Padovani, M., Seifried, D., and Walch, S., 2022, A&A, 664, 150

Cosmic-ray-induced H2 line emission. Astrochemical modeling and implications for JWST observations

36. Dasyra, K.M., Paraschos, G.F., Bisbas, T.G., Combes, F., and Fernandez-Ontiveros, J.A., 2022, NatAs, 6, 1077

Insights into the collapse and expansion of molecular clouds in outflows from observable pressure gradients

35. Gaches, B.A.L., Bisbas, T.G., and Bialy, S., 2022, A&A, 658, 151

The Impact of Cosmic-Ray Attenuation on the Carbon Cycle Emission in Molecular Clouds

34. Bisbas, T.G., Tan, J.C. and Tanaka, K.E.I., 2021, MNRAS, 502, 2701

Photodissociation Region Diagnostics Across Galactic Environments

33. Lim, W. Nakamura F., Wu, B., Bisbas, T.G., Tan J.C., et al., 2021, PASJ, 73, S239

Star Cluster Formation in Orion A

32. Seifried, D., Haid, S., Walch, S., Borchert, E.M., Bisbas, T.G., 2020, MNRAS, 492, 1465

SILCC-Zoom: H2 and CO-dark gas in molecular clouds — The Impact of feedback and magnetic fields

31. Gaches, B. A. L., Offner, S. S. R., Bisbas, T.G., 2019, ApJ, 883, 190

The Astrochemical Impact of Cosmic Rays in Protoclusters II: CI-to-H2 and CO-to-H2 conversion factors

30. Gaches, B. A. L., Offner, S. S. R., Bisbas, T. G., 2019, ApJ, 878, 105

The Astrochemical Impact of Cosmic Rays in Protoclusters I: Molecular Cloud Chemistry

29. Bisbas, T. G., Schruba, A. & van Dishoeck, E.F., 2019, MNRAS, 485, 3097

Simulating the atomic and molecular content of molecular clouds using probability distributions of physical parameters

28. Williams, R. J. R., Bisbas, T. G., Haworth, T. J., Mackey, J., 2018, MNRAS, 479, 2018.

The classical D-type expansion of spherical HII regions

27. Banerji, M., Jones, G. C., Wagg, J., Carilli, C. L., Bisbas, T. G., Hewett, P. C., 2018, MNRAS, 479, 1154.

The interstellar medium properties of heavily reddened quasars and companions at z~2.5 with ALMA and JVLA

26. Haworth, T. J., Glover S. C. O., Koepferl, C. M., Bisbas, T. G., Dale, J. E., 2018, New Astronomy Reviews, 82, 1.

Synthetic observations of star formation and the interstellar medium [Review article]

25. Papadopoulos, P. P., Bisbas, T. G., Zhang Z-Y., 2018, MNRAS, 478, 1716.

New places and phases of CO-poor/CI-rich molecular gas in the Universe

24. Bisbas, T. G., Tan, J. C., Csengeri, T., Wu, B., Lim, W., and 4 co-authors, 2018, MNRAS, 478L, 54.

The inception of star cluster formation revealed by [CII] emission around an Infrared Dark Cloud

23. Li, Q., Tan, J. C., Christie, D., Bisbas, T. G., & Wu, B., 2017, PASJ, 70, 56.

The interstellar medium and star formation of galactic disks. I. Interstellar medium and giant molecular cloud properties with diffuse far-ultraviolet and cosmic-ray backgrounds

22. Bisbas, T. G., Tanaka, K. E. I., Tan, J. C., Wu, B., & Nakamura, F., 2017, ApJ, 850, 23.

GMC Collisions as Triggers of Star Formation. V. Observational Signatures

21. Bothwell, M. S., Aguirre, J. E., Aravena, M., Bethermin, M., Bisbas, T. G., et al., 2017, MNRAS, 466, 2825.

ALMA observations of atomic carbon in z~4 dusty star-forming galaxies

20. Bisbas, T. G., van Dishoeck, E. F., Papadopoulos, P. P., Szücs, L., Bialy, S., & Zhang, Z-Y, 2017, ApJ, 839, 90.

Cosmic-ray Induced Destruction of CO in Star-forming Galaxies

19. Accurso, G., Saintonge, A., Bisbas, T. G., & Viti, S., 2017, MNRAS, 464, 3315.

Radiative transfer meets Bayesian statistics: where does a galaxy’s [CII] emission come from?

18. Haworth, T. J., Boubert, D., Facchini, S., Bisbas, T. G., & Clarke, C. J., 2016, MNRAS, 463, 3616.

Photochemical-dynamical models of externally FUV irradiated protoplanetary discs

17. Krips, M., Martín, S., Sakamoto, K., Aalto, S., Bisbas, T.G., et al., 2016, A&A, 592, L3.

ACA [CI] observations of the starburst galaxy NGC 253

16. Facchini, S., Clarke, C. J., & Bisbas, T. G. 2016, MNRAS, 457, 3593.

External photoevaporation of protoplanetary discs in sparse stellar groups: the impact of dust growth

15. Bisbas, T. G., Haworth, T. J., Barlow, M. J., Viti, S., and 3 co-authors, 2015 , MNRAS, 454, 2828.

TORUS-3DPDR: a self-consistent code treating three-dimensional photoionization and photodissociation regions

14. Haworth, T. J., Harries, T. J., Acreman, D. M., & Bisbas, T. G., 2015, MNRAS, 453, 2277.

On the relative importance of different microphysics on the D-type expansion of galactic H II regions

13. Bisbas, T. G., Haworth, T. J., Williams, R. J. R., Mackey, J., and 15 co-authors, 2015, MNRAS, 453, 1324.

STARBENCH: the D-type expansion of an HII region

12. Walch, S., Whitworth, A. P., Bisbas, T. G., Hubber, D. A., Wünsch, R. 2015, MNRAS, 452, 2794.

Comparing simulations of ionization triggered star formation and observations in RCW 120

11. Bisbas, T. G., Papadopoulos, P. P., & Viti, S. 2015, ApJ, 803, 37.

Effective Destruction of CO by Cosmic Rays: Implications for Tracing H2 Gas in the Universe

10. Gaches, B. A. L., Offner, S. S. R., Rosolowsky, E. W., & Bisbas, T. G., 2015, ApJ, 799, 235.

Astrochemical Correlations in Molecular Clouds

9. Bisbas, T. G., Bell, T. A., Viti, S., Barlow, M.J., Yates, J.A., & Vasta, M., 2014, MNRAS, 443, 111.

A photodissociation region study of NGC 4038

8. Offner, S. S. R., Bisbas, T. G., Bell, T. A., & Viti, S. 2014, MNRAS, 440, L81.

An alternative accurate tracer of molecular clouds: the ‘XCI-factor’

7. Walch, S., Whitworth, A. P., Bisbas, T. G., Wünsch, R., & Hubber, D. A. 2013, MNRAS, 435, 917.

Clumps and triggered star formation in ionized molecular clouds

6. Offner, S. S. R., Bisbas, T. G., Viti, S., & Bell, T. A. 2013, ApJ, 770, 49.

Modeling the atomic-to-molecular Transition and Chemical Distributions of Turbulent Star-forming Clouds

5. Bisbas, T. G., Bell, T. A., Viti, S., Yates, J., & Barlow, M. J. 2012, MNRAS, 427, 2100.

3D-PDR: a new three-dimensional astrochemistry code for treating photodissociation regions

[Click here to visit the code website]

4. Walch, S. K., Whitworth, A. P., Bisbas, T., Wünsch, R., & Hubber, D. 2012, MNRAS, 427, 625.

Dispersal of molecular clouds by ionizing radiation

3. Bisbas, T. G., Wünsch, R., Whitworth, A. P., Hubber, D. A., & Walch, S. 2011, ApJ, 736, 142.

Radiation-driven Implosion and Triggered Star Formation

2. Bisbas, T. G., Wünsch, R., Whitworth, A. P., & Hubber, D. A. 2009, A&A, 497, 649.

Smoothed particle hydrodynamics simulations of expanding HII regions. I. Numerical method and applications

1. Stamatellos, D., Whitworth, A. P., Bisbas, T.G., & Goodwin, S. 2007, A&A, 475, 37.

Radiative transfer and the energy equation in SPH simulations of star formation


I have written the book “The Interstellar Medium, Expanding Nebulae and Triggered Star Formation; theory and simulations”, published by Springer (Springer Briefs in Astronomy).


The book brings together the theoretical aspects of star formation and ionized regions with the most up-to-date simulations and observations. Beginning with the basic theory of star formation, the physics of expanding HII regions are reviewed in detail and a discussion on how a massive star can give birth to tens or hundreds of other stars follows. The theoretical description of star formation is shown in simplified and state-of-the-art numerical simulations, describing in a more clear way how feedback from massive stars can trigger star and planet formation. This is also combined with spectacular images of nebulae taken by talented amateur astronomers. The latter is very likely to stimulate the reader to observe the structure of nebulae from a different point of view, and to better understand the associated star formation therein.


Ph.D. Thesis

Click here to download my PhD Thesis (2009, Cardiff University)

Title: Smoothed Particle Hydrodynamics simulations of expanding HII regions

Abstract: This thesis deals with numerical simulations of expanding ionized regions, known as HII regions. We implement a new three dimensional algorithm in Smoothed Particle Hydrodynamics for including the dynamical effects of the interaction between ionizing radiation and the interstellar medium. This interaction plays a crucial role in star formation at all epochs. We study the influence of ionizing radiation in spherically symmetric clouds. In particular, we study the spherically symmetric expansion of an HII region inside a uniform-density, non-self-gravitating cloud. We examine the ability of our algorithm to reproduce the known theoretical solution and we find that the agreement is very good. We also study the spherically symmetric expansion inside a uniform-density, self-gravitating cloud. We propose a new differential equation of motion for the expanding shell that includes the effects of gravity. Comparing its numerical solution with the simulations, we find that the equation predicts the position of the shell accurately. We also study the expansion of an off-centre HII region inside a uniform-density, non- self-gravitating cloud. This results in an evolution known as the rocket effect, where the ionizing radiation pushes and accelerates the cloud away from the exciting star leading to its dispersal. During this evolution, cometary knots appear as a result of Rayleigh-Taylor and Vishniac instabilities. The knots are composed of a dense head with a conic tail behind them, a structure that points towards the ionizing source. Our simulations show that these knots are very reminiscent of the observed structures in planetary nebula, such as in the Helix nebula. The last part of this thesis is dedicated to the study of cores ionized by an exciting source which is placed outside and far away from them. The evolution of these cores is known as radiation driven compression (or implosion). We perform simulations and compare our findings with results of other workers and we find that they agree very well. Using stable Bonnor-Ebert spheres, we extend our study to modelling triggered star formation within these cores as they are overrun and compressed by the incident ionizing flux. We construct a parameter space diagram and we map regions where star formation is expected to be observed. All the above results indicate that the algorithm presented in this thesis works well for treating the propagation of ionizing radiation. This new algorithm provides the means to explore and evaluate the role of ionizing radiation in regulating the efficiency and statistics of star formation.