অদৃশ্য আলোতে আকাশগঙ্গার অন্তর
পৃথিবীর সবচেয়ে ভালো রেডিও দুরবিন দিয়ে তোলা হয়েছে আমাদের গ্যালাক্সি আকাশগঙ্গার এক অবিশ্বাস্য ছবি। রেডিও তরঙ্গ আমাদের চোখে ধরা দেয় না, তবে এই অদৃশ্য আলো দেখার ক্ষমতা আছে রেডিও টেলিস্কোপের, […]
Entries by Khan Asad
Mining mini-halos with MeerKAT I. Calibration and imaging
Radio mini-halos are clouds of diffuse, low-surface brightness synchrotron emission that surround the Brightest Cluster Galaxy (BCG) in massive cool-core galaxy clusters. In this paper, we use third generation calibration […]
The 1.28 GHz MeerKAT Galactic Center Mosaic
The inner $\sim 200$ pc region of the Galaxy contains a 4 million $M_\odot$ supermassive black hole (SMBH), significant quantities of molecular gas, and star formation and cosmic-ray energy densities that […]
Primary beam effects of radio astronomy antennas – II. Modelling MeerKAT L-band beams
After a decade of design and construction, South Africa’s SKA-MID precursor MeerKAT has begun its science operations. To make full use of the widefield capability of the array, it is […]
Constraining the intergalactic medium at z ≈ 9.1 using LOFAR Epoch of Reionization observations
We derive constraints on the thermal and ionization states of the intergalactic medium (IGM) at redshift $\approx 9.1$ using new upper limits on the 21-cm power spectrum measured by the […]
Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR
A new upper limit on the 21 cm signal power spectrum at a redshift of $z \approx 9.1$ is presented, based on 141 h of data obtained with the Low-Frequency Array (LOFAR). […]
The 1.28 GHz MeerKAT DEEP2 Image
We present the confusion-limited 1.28 GHz MeerKAT DEEP2 image covering one $\theta_b\approx 68’$ FWHM primary-beam area with $\theta=7.6^{”}$ FWHM resolution and $\sigma_n=0.55\pm 0.01$ $\mu$Jy beam$^{-1}$ rms noise. Its J2000 center […]