“Hosein Haghi”

IPM Positions

Resident Researcher, School of Astronomy

Non IPM Affiliations

Associate Professor of IASBS
, Universitate Bonn

Research Interests

1- Astrophysics of galaxies
2- Dynamics of star clusters
3- Dark matter problem and alternatives


1- Editorial Board of Iranian Journal of Astronomy and Astrophysics
2- Board Member of Astronomy Society of Iran from 2012 until 2018
3- team leader of Iran national Astronomy Olympiad 2012-2023

Research Activities

We have published several papers based on direct N-body calculations in this regard. Our simulations show that the evolution of star clusters strongly depends on their initial conditions as well as their environment (Zonoozi et al 2011, 2014, 2016a,b, 2017; Haghi et al. 2014, 2015, 2017, 2020). For example, a cluster that is initially set up mass segregated will expand twice more compared to a similar cluster but without PMS, and consequently will dissolve faster (Baumgardt et al. 2009, Haghi et al. 2014). Moreover, the gas expulsion strongly affects further dynamical evolution of star clusters. In young, still gas-embedded star clusters, the rapid expulsion of the residual-gas that did not form stars causes star clusters to become super-virial on a dynamical timescale and hence a fraction of the originally bound stars becomes unbound and leaves the cluster (Baumgardt & Kroupa 2007, Haghi et al. 2015). Another important parameters on the evolution of star clusters is the number of black holes (BHs) and neutron stars (NSs) remaining from the stellar evolution of massive stars and retained in the cluster. Over the last few years, there has been a significant change in our understanding of BHs in GCs. For the first time, Strader et al. (2012) discovered two BHs within the Galactic GC M22 by radio observations. Considering these BHs are accreting from white dwarf companions and by using formation and survival rates, about 5–100 BHs are thought to be present in M22. On the theoretical side, several studies concluded that old clusters might actually be able to retain significant numbers of BHs (Breen & Heggie 2013, Wang 2020). Breen & Heggie (2013) provided analytic calculations and direct N-body simulations, which both suggest that the flow of energy between the sub-cluster of BHs and the other stars is ultimately controlled by the entire cluster. By numerical simulation of star clusters with canonical IMF, Banerjee and Kroupa (2011), for the first time, predicted the formation of dark star clusters (DSC) as a result of the rapid removal of stars from the outer parts of a cluster by the strong tidal field of host galaxy. The main aim of this research project is to extend our previous calculations to more realistic initial conditions and shedding more light on the evolution of star clusters, focusing on the stellar MF of GCs by means of direct N-body simulations.

Present Research Project at IPM

Probing the evidence for top-heavy IMF and primordial mass segregation in star clusters
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