Publications

List of Publication from ADS

List of Publication from arXiv

Refereed Journals:

1. First upper limits on the 21-cm signal power spectrum of neutral hydrogen at  z=9.16  from the LOFAR 3C196 field, E. Ceccotti, A. R. Offringa, F. G. Mertens, L. V. E. Koopmans, S. Munshi, J. K. Chege, A. Acharya, S. A. Brackenhoff, E. Chapman, B. Ciardi, R. Ghara, S. Ghosh, S. K. Giri, C. Höfer, I. Hothi, G. Mellema, M. Mevius, V. N. Pandey, S. Zaroubi, MNRAS (arXiv:2504.18534)

2. Asking Fast Radio Bursts (FRBs) for More than Reionization History, A. K. Shaw,   R. Ghara, P. Beniamini, S. Zaroubi, P. Kumar, 2024, Apj

3. Effects of Large Optical Depth on CD HI 21-cm Non-Gaussian Signal, Iffat Nasreen, Kanan K. Datta, Abinash K. Shaw, Leon Noble, Raghunath Ghara, Sk. Saiyad Ali, Arnab Mishra, Mohd Kamran, Suman Majumdar,  MNRAS, (arXiv:2506.23011)

4. Exploring the effect of different cosmologies on the Epoch of Reionization 21-cm signal with POLAR, Acharya, Anshuman, Ma, Qing-bo, Giri, Sambit K., Ciardi, Benedetta,  Ghara, Raghunath, Mellema, Garrelt,  Zaroubi, Saleem, Hothi, Ian, Iliev, Ilian T., Koopmans, Léon V. E., Bianco, Michele,  Monthly Notices of the Royal Astronomical Society 

5. Improved upper limits on the 21-cm signal power spectrum at z=17.0 and z=20.3 from an optimal field observed with NenuFAR, S. Munshi, F. G. Mertens, J. K. Chege, L. V. E. Koopmans, A. R. Offringa, B. Semelin, R. Barkana, J.Dhandha, A. Fialkov, R. Mriot, S. Sikder, A. Bracco, S. A. Brackenhoff, E. Ceccotti, R. Ghara, S. Ghosh, I. Hothi, M. Mevius, P. Ocvirk, A. K. Shaw, S. Yatawatta, P. Zarka, MNRAS, (arXiv:2507.10533)

6. Extracting the Epoch of Reionization Signal with 3D U-Net Neural Networks Using Data-Driven Systematic Effect Model, Gao, Liyang ; Koopmans, Léon V. E. ; Mertens, Florent G.; Munshi, Satyapan ; Li, Yichao ; Brackenhoff, Stefanie A. ; Ceccotti, Emilio ; Kariuki Chege, J. ; Acharya, Anshuman ; Ghara, Raghunath ; Giri, Sambit K. ; Iliev, Ilian T. ; Mellema, Garrelt; Zhang, Xin, 2025, Accepted in ApJ, (arXiv:2412.16853)

7. Constraints on the state of the IGM at z ∼ 8 − 10 using redshifted 21-cm observations with LOFAR, R. Ghara, S. Zaroubi, B. Ciardi, G. Mellema, S. K. Giri, F. G. Mertens, M. Mevius, L. V. E. Koopmans, I. T. Iliev, A. Acharya, S. A. Brackenhoff, E. Ceccotti, K. Chege, I. Georgiev, S. Ghosh, I. Hothi, C. Höfer, Q. Ma, S. Munshi, A. R. Offringa, A. K. Shaw, V. N. Pandey and S. Yatawatta,  2025,  Astronomy & Astrophysics, Volume 699, id.A109,  21 pp.

8. Inferring IGM parameters from the redshifted 21-cm Power Spectrum using Artificial Neural Networks, M. Choudhury, R. Ghara, S. Zaroubi, B. Ciardi, L. V. E. Koopmans, G. Mellema, A. K. Shaw, A. Acharya, I. T. Iliev, Qing-Bo Ma, S. K. Giri, 2025, Journal of Cosmology and Astroparticle Physics, Volume 2025, Issue 06, id.003, 32 pp. (arXiv:2407.03523)

9. Near field imaging of local interference in radio interferometric data: Impact on the redshifted 21-cm power spectrum, S. Munshi, F.G. Mertens, L.V.E. Koopmans, M. Mevius, A.R. Offringa, B. Semelin, C. Viou, A. Bracco, S.A. Brackenhoff, E. Ceccotti, J.K. Chege, A. Fialkov, L.Y. Gao, R. Ghara, S. Ghosh, A.K. Shaw, P. Zarka, S. Zaroubi, B. Cecconi, S. Corbel, J.N. Girard, J.M. Griessmeier, O. Konovalenko, A. Loh, P. Tokarsky, O. Ulyanov, V. Zakharenko, 2025, Astronomy & Astrophysics, Volume 697, id.A203, 19 pp. 

10. Deeper multi-redshift upper limits on the Epoch of Reionization 21-cm signal power spectrum from LOFAR between z=8.3 and z=10.1. F. G. Mertens, M. Mevius, L. V. E. Koopmans, A. R. Offringa, S. Zaroubi, A. Acharya, S. A. Brackenhoff, E. Ceccotti, E. Chapman, K. Chege, B. Ciardi, R. Ghara, S. Ghosh, S. Giri, I. Hothi, C. Höfer, I. T. Iliev, V. Jelić, Q. Ma, G. Mellema, S. Munshi, V. N. Pandey, and S. Yatawatta, 2025, Astronomy & Astrophysics, Volume 698, id.A186, 32 pp.

11. Spectral modelling of Cygnus A between 110 and 250 MHz. Impact on the LOFAR 21-cm signal power spectrum, Ceccotti, E. ; Offringa, A. R. ; Koopmans, L. V. E. ; Mertens, F. G.; Mevius, M. ; Acharya, A. ; Brackenhoff, S. A. ; Ciardi, B. ; Gehlot, B. K. ; Ghara, R. ; Chege, J. K. ; Ghosh, S. ; Höfer, C. ; Hothi, I. ; Iliev, I. T. ; McKean, J. P. ; Munshi, S. ; Zaroubi, S., 2025, Astronomy & Astrophysics, Volume 696, id.A56, 22 pp., (arXiv:2502.18459)

12. Impact of the Epoch of Reionization sources on the 21-cm bispectrum, Noble, L. ; Kamran, M. ; Majumdar, S. ; Shekhar M., C. ; Ghara, R. ; Mellema, G. ; Iliev, I. T. ; Pritchard, J. R., 2024, JCAP, Volume 2024, Issue 10, id.003, 32 pp. (arXiv:2406.03118)

13. Revised LOFAR upper limits on the 21-cm signal power spectrum at z ≈ 9.1 using machine learning and gaussian process regression, Acharya, A. ; Mertens, F. ; Ciardi, B. ; Ghara, R.; Koopmans, L. V. E. ; Zaroubi, S., 2024, MNRAS letter, Volume 534, Issue 1, pp.L30-L34 (arXiv:2408.10051)

14. Probing the intergalactic medium during the Epoch of Reionization using 21-cm signal power spectra, Ghara, R.; Shaw, A. K.; Zaroubi, S.; Ciardi, B.; Mellema, G.; Koopmans, L. V. E.; Acharya, A.; Choudhury, M.; Giri, S. K.; Iliev, I. T.; Ma, Q. and Mertens, F., 2024,  A&A, Volume 687, id.A252, 15 pp. (arXiv:2404.11686)

15. The morphology of the redshifted 21-cm signal from the Cosmic Dawn, Ghara, R.; Bag, S.; Zaroubi, S.; Majumdar, S., 2024, Monthly Notices of the Royal Astronomical Society, Volume 530, Issue 1, pp.191-202, (arXiv:2308.00548)

16. 21-cm Signal from the Epoch of Reionization: A Machine Learning upgrade to Foreground Removal with Gaussian Process Regression, Acharya, A.; Mertens, F.; Ciardi, B.;  Ghara, R.; Koopmans,  L. V. E.; Giri, S.K.; Hothi, I.; Ma, Q.; Mellema, G.; Munshi, S.; Jan 2024 MNRAS, Volume 527, Issue 3, pp.7835-7846 (arXiv:2311.16633)

17. First upper limits on the 21-cm signal power spectrum from the Cosmic Dawn from one night of observations with NenuFAR, S. Munshi; F. G. Mertens; L. V. E. Koopmans; A. R. Offringa; B. Semelin; D. Aubert; R. Barkana; A.Bracco; S. A. Brackenhoff; B. Cecconi; E. Ceccotti; S. Corbel; A. Fialkov; B. K. Gehlot; R. Ghara; J.N. Girard; J. M. Grießmeier; C. Höfer; I. Hothi; R. Mériot; M. Mevius; P. Ocvirk; A. K. Shaw; G.Theureau; S. Yatawatta; P. Zarka and S. Zaroubi, 2023, A&A (arXiv:2311.05364).

18. POLAR - I: linking the 21-cm signal from the epoch of reionization to galaxy formation, Ma, Q.; Ghara, R.; Ciardi, B.; Iliev, I. T.; Koopmans, L. V.~E.; Mellema, G.; Mondal, R.; and Zaroubi, S., April 2023, MNRAS, Volume 522, Issue 3, pp.3284-3297, (arXiv:2304.09508)

19.   Studying the Multi-frequency Angular Power Spectrum of the Cosmic Dawn 21-cm Signal, Shaw, A. K.; Ghara, R.; Zaroubi, S.; Mondal, R.; Mellema, G.; Mertens, F.; Koopmans, L. V.~E. and Semelin, B., June 2023, MNRAS, Volume 522, Issue 2, pp.2188-2206. (arXiv:2302.01127)

20.  Assessing the impact of two independent direction-dependent calibration algorithms on the LOFAR 21-cm signal power spectrum, Gan, H.; Mertens, F. G.; Koopmans, L. V. E.; Offringa, A. R.; Mevius, M.; Pandey, V. N.; Brackenhoff, S. A.; Ceccotti, E.; Ciardi, B.; Gehlot, B. K.;  Ghara, R.; Giri, S. K.; Iliev, I. T.; Munshi, S., 2023,  A&A, Volume 669, article no. A20, (arXiv:2209.07854)

21.  Studying Cosmic Dawn using redshifted HI 21-cm signal: A brief review, Bera, A.;  Ghara, R.; Chatterjee, A.; Datta, K. K.; Samui, S., 2023, JOAA, Volume 44, Article number 10,  (arXiv:2210.12164)

22. Probing early universe through redshifted 21-cm signal: Modelling and observational challenges, Shaw, A. K.; Chakraborty, A.; Kamran, M.; Ghara, R.; Choudhuri, S.; Ali, S. S.; Pal, S.; Ghosh, A.; Kumar, J.; Dutta, P.; Sarkar, A. K;  2023, JOAA, Volume 44, Article number 4 (arXiv:2211.05512)

23. Redshifted 21-cm bispectrum: Impact of the source models on the signal and IGM physics from the Cosmic Dawn, Kamran, M.;  Ghara, R.; Majumdar, S.; Mellema, G.; Bharadwaj, S.; Pritchard, J. R.; Mondal, R.; Iliev, I. T.; 2022, JCAP,  Volume 2022, Issue 11, id.001, 29 pp. (arXiv:2207.09128)

24.  Probing the Epoch of Reionization using synergies of line intensity mappings, Murmu, C. S.; Ghara, R.; Majumdar, S.; Datta, K. K., 2022; JOAA, Volume 43, Issue 2, article id.104, (arXiv:2210.09612)

25. Statistical analysis of the causes of excess variance in the 21 cm signal power spectra obtained with the Low-Frequency Array, Gan, H.; E Koopmans, L. V.; Mertens, F. G.; Mevius, M.; Offringa, A. R.; Ciardi, B.; Gehlot, B. K.; Ghara, R.; Ghosh, A.; Giri, S. K.; Iliev, I. T.; Mellema, G.; Pandey, V. N.; Zaroubi, S., 2022, A&A, Volume 663, id.A9, 28 pp. (arXiv:2203.02345)

26. Degree-Scale Galactic Radio Emission at 122 MHz around the North Celestial Pole with LOFAR-AARTFAAC, Gehlot, B. K. ; Koopmans, L. V. E. ; Offringa, A. R. ; Gan, H. ; Ghara, R. ; Giri, S. K. ; Kuiack, M. ; Mertens, F. G. ; Mevius, M. ; Mondal, R. ; Pandey, V. N. ; Shulevski, A. ; Wijers, R. A. M. J. ; Yatawatta, S.;  2021, A&A, Volume 662, id.A97, 11 pp. (arXiv:2112.00721)

27. Astrophysical information from the Rayleigh-Jeans Tail of the CMB, Ghara, R.; Mellema, G.; Zaroubi, S.;  2022, JCAP, Volume 2022, Issue 03, id.055, 18 pp. (arXiv:2108.13593)

28. A numerical study of 21-cm signal suppression and noise increase in direction-dependent calibration of LOFAR data, M. Mevius, F. Mertens, L.V.E Koopmans, A. R.Offringa, S. Yatawatta, E. Chapman, B. Ciardi, H. Gan, B. K. Gehlot, R. Ghara, A. Ghosh,  S. K. Giri, I. T. Iliev, G. Mellema, V. N. Pandey, 2021, MNRAS,  Volume 509, Issue 3, pp.3693-3702 (arXiv:2111.02537)

29. Large HI optical depth and Redshifted  21-cm signal from cosmic dawn, Datta, K. K.; Ghara, R.; Haque, A.; Majumdar, S., 2021, MNRAS, Volume 509, Issue 1, pp.945-953 (arXiv:2110.06925)

30. Redshift-space distortions in simulations of the 21-cm signal from the cosmic dawn, H. E. Ross, S. K. Giri, G. Mellema, K. L. Dixon, R. Ghara, I. T. Iliev, 2021, MNRAS, Volume 506, Issue 3, pp.3717-3733, (arXiv:2011.03558)

31. Constraining the state of the intergalactic medium during the Epoch of Reionization using MWA 21-cm signal observations, Ghara, R., Giri, S. K.; Ciardi, B.;  Mellema, G.; Zaroubi, S.  2021, MNRAS,  Volume 503, Issue 3, pp 4551-4562 (arXiv:2103.07483)

32. Prospects of constraining EoR models from morphology of 21cm maps, Kapahtia, A.; Chingangbam, P.;  Ghara, R.; Appleby, S.; Choudhury, T. R., 2021, JCAP, Volume 5, 026. (arXiv:2101.03962)

33. Redshifted 21-cm bispectrum II: Impact of the spin temperature fluctuations and redshift space distortions on the signal from the Cosmic Dawn,  Kamran, M.;  Ghara, R.; Majumdar, S.; Mondal, R.; Mellema, G.; Bharadwaj, S.; Pritchard, J. R.; Iliev, I. T., 2021, MNRAS, Volume 502, Issue 3, pp.3800-3813 (arXiv:2012.11616)

34. Interpreting LOFAR 21-cm signal upper limits at z $\approx$ 9.1 in the context of high-z galaxy and reionisation observations, Greig, B.; Mesinger, A.; Koopmans, L. V. E.; Ciardi, B.; Mellema, G.; Zaroubi, S.; Giri, S. K.; Ghara, R.; Ghosh, A.; Iliev, I. T.; Mertens, F. G.; Mondal, R.; Offringa, A. R.; Pandey, V. N., 2021, MNRAS, Volume 501, Issue 1, pp.1-13 (arXiv:2006.03203)

35.  Comparing Foreground Removal Techniques for Recovery of the LOFAR 21cm Power Spectrum, Hothi, Ian; Chapman, Emma; Pritchard, Jonathan R.; Mertens, F. G.; Koopmans, L. V. E.; Ciardi, B.; Gehlot, B. K.; Ghara, R.; Ghosh, A.; Giri, S. K.; Iliev, I. T.; Jelić, V.; Zaroubi, S., 2021, MNRAS, Volume 500, Issue 2, pp.2264-2277 (arXiv:2011.01284) 

36. Tight Constraints on the Excess Radio Background at z = 9.1 from LOFAR,  Mondal, R.; Fialkov, A.; Fling, C.; Iliev, I. T.; Barkana, R.; Ciardi, B.; Mellema, G.; Zaroubi, S.; Koopmans, L. V. E; Mertens, F. G.; Gehlot, B. K.;  Ghara, R.; Ghosh, A.; Giri, S. K.; Pandey, V. N. 2020, MNRAS, Volume 498, Issue 3, pp.4178-4191 (arXiv:2004.00678)

37. Bayesian approach to constraining the properties of ionized bubbles during reionization,  Ghara, R. & Choudhury, T. R., 2020, MNRAS, Volume 496, Issue 1, pp.739-753 (arXiv:1909.12317) 

38. Constraining the intergalactic medium at z ≈ 9.1 using LOFAR Epoch of Reionization observations, Ghara, R. et al (LOFAR collaboration), 2020, MNRAS., Volume 493, Issue 4, pp.4728-4747 ( arXiv:2002.07195)

39. Improved upper limits on the 21-cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR, Merten et al (LOFAR collaboration), 2020, MNRAS, Volume 493, Issue 2, p.1662-1685 ( arXiv:2002.07196)

40. Impact of Lyman-α heating on the global 21-cm signal from the Cosmic Dawn, Ghara, R. & Mellema, G. 2020, MNRAS, 492, 634 (arXiv: 1904.09999)

41. Cosmological implications of the composite spectra of galactic X-ray binaries constructed using MAXI data, Islam, N., Ghara, R., Paul, B., Choudhury, T. R. & Nath B. B. 2019, MNRAS, 487, 2785-2796 (arXiv:1905.10386)

42. Fuzzy Dark Matter at Cosmic Dawn: New 21-cm Constraints, Nebrin, O., Ghara, R., & Mellema, G. 2019, JCAP, 04, 051 (arXiv:1812.09760)

43. Position-dependent power spectra of the 21-cm signal from the epoch of reionization, Giri, S. K., D’Aloisio A., Mellema, G., Komatsu, E., Ghara, R., & Majumdar, S. 2019, JCAP, 02, 058 (arXiv:1811.09633)

44. Evaluating the QSO contribution to the 21-cm signal from the Cosmic Dawn, Ross, H., Dixson, K. L., Ghara, R., Iliev, I., T. & Mellema, G. 2018, MNRAS, 487, 1101, (arXiv:1808.03287) 

45. Optimal identification of HII regions during reionization in 21-cm observations, Giri, S. K., Mellema, G. & Ghara, R., (arXiv:1801.06550)

46. Prediction of the 21-cm signal from reionization: comparison between 3D and 1D radiative transfer schemes, Ghara, R., Mellema, G., Giri, S. K., Choudhury, T. R., Datta, K. K. & Majumdar, S. 2018, MNRAS, 476, 1741, (arXiv:1710.09397) 

47. Measuring the reionization 21 cm fluctuations using clustering wedges, Raut, D., Choudhury, T. R., Datta, Ghara, R. 2018, MNRAS, 475, 438, (arXiv:1708.02824)

48. Imaging the redshifted 21 cm pattern around the first sources during the cosmic dawn using the SKA, Ghara, R., Choudhury, T. R., Datta, K. K., & Choudhuri, S. 2017, MNRAS, 464, 2234, (arXiv:1607.02779)

49. Line-of-Sight Anisotropies in the Cosmic Dawn and Epoch of Reionization 21- cm Power Spectrum, Majumdar, S., Datta, K.K., Ghara, R. et al. J Astrophys Astron (2016) 37: 32, (arXiv:1610.08180)

50. Modelling the 21-cm Signal from the Epoch of Reionization and Cosmic Dawn, Choudhury, T.R., Datta, K., Majumdar, S., Ghara, R. et al. J Astrophys Astron (2016) 37: 29, (arXiv:1610.08179)

51. Probing Individual Sources during Reionization and Cosmic Dawn using Square Kilometre Array HI 21-cm Observations, Datta, K.K., Ghara, R., Majumdar, S. et al. J Astrophys Astron (2016) 37: 27, (arXiv:1610.08177)

52. 21-cm signature of the first sources in the Universe: Prospects of detection with SKA, Ghara, R., Choudhury, T. R., & Datta, K. K. 2016, MNRAS, 460, 827, (arXiv:1511.07448)

53. 21-cm signal from cosmic dawn : Imprints of the light-cone effects, Ghara, R., Datta, K. K., & Choudhury, T. R. 2015, MNRAS, 453, 3143, (arXiv:1504.05601)

54. 21 cm signal from cosmic dawn: imprints of spin temperature fluctuations and peculiar velocities, Ghara, R., Choudhury, T. R., & Datta, K. K. 2015, MNRAS, 447, 1806 (arXiv:1406.4157) 

Conference Proceedings:

1. Understanding the impact of Light cone effect on the EoR/CD 21-cm power spectrum, Datta, K. K., Mondal, R., Ghara, R., Bharadwaj, S. & Choudhury, T. R. 2018, IAUS, 333, 12 

2. Prospects of detection of the first sources with SKA using matched filters, Ghara, R., Choudhury, T. R., Datta, K. K., Mellema, G., Choudhuri, S., Majumdar, S. & Giri, S. K. 2018, IAUS, 333, 122 

3. Analysis of 21-cm tomographic data, Mellema, G., Giri, S. K.& Ghara, R., 2018, IAUS, 333, 26

Submitted Articles

1. Enhancing the detectability of ionized Regions during the Epoch of Reionization. 2025, submitted to JCAP

Other Articles

1. Probing IGM Physics during Cosmic Dawn using the Redshifted 21-cm Bispectrum}, Kamran, M.; Majumdar, S.; Ghara, R.; Mellema, G.; Bharadwaj, S.; Pritchard, J. R.; Mondal, R.; Iliev, I. T.; 2021,  (arXiv:2108.08201)