High mass star formation towards G358.69+0.03

Master Colloquium
Anahat Cheema

In our work, we investigate the high mass star formation activity in the region centered at (l,b)=(358.69°, 0.03°) near the Galactic center. In order to identify and characterise the HII regions, we use data from the GLOSTAR survey, which is a wideband radio (4-8 GHz) survey of the Milky Way combining data from the Karl G. Jansky Very Large Array (VLA) and the Effelsberg 100m telescope. Using BLOBCAT source extraction software which uses flood-fill algorithm to detect sources in 2 dimensional astronomical images, we identified 46 radio sources in the region. Candidate HII regions are cataloged based on association with at least one multiwavelength counterpart. For this, we used mid-infrared (GLIMPSE, MIPSGAL and WISE), far-infrared (Hi-GAL) and submillimeter (ATLASGAL) archival data. In total, we have identified 43 HII region candidates. We compute the properties of these HII regions, such as the Lyman continuum photon rate, ZAMS spectral type, dynamical age etc. The HII region candidates are distributed in a ring-like formation. We also observe enhancement of ATLASGAL clumps and infrared sources towards south-east of the ring, suggesting triggered star formation in the region.

Mapping the Milky Way: Galactic cartography in the age of high precision parallaxes

Main Colloquium
Dr. Ronald Drimmel
Osservatorio astrofisico di Torino, INAF (Italy)

Galactic studies is undergoing a renaissance in the current decade, thanks not only to Gaia, but to ground-breaking astrometry in the NIR and radio. I will give an update on the latest Gaia results following on the it's last data release about the structure of our Galaxy, with particular focus on the disk. Thanks to a recent Lorentz Center workshop with the same title as this talk, I will attempt to put Gaia's contribution in the context of other recent results from the NIR and radio. Integrating all these together I hope to share what we are learning and hope to soon learn about the Milky Way.

A challenge to the standard cosmological model

Special Colloquium
Prof. Subir Sarkar
University of Oxford

In the ΛCDM cosmological model the Universe is assumed to be isotropic & homogeneous when averaged on large scales. That the CMB has a dipole anisotropy is interpreted as due to our peculiar motion because of local inhomogeneity. There should then be a similar dipole in the sky distribution of high redshift sources. Using catalogues of radio sources and quasars we find that this expectation is rejected at >5σ, i.e. the distribution of distant matter is not isotropic in the 'CMB frame’. This calls into question the standard practice of boosting to this frame to analyse cosmological data, in particular to infer isotropic acceleration of the Hubble expansion rate from Type Ia supernovae, which is interpreted as due to Λ.

Constraining scalarization in Gauss-Bonnet gravity through binary pulsars

Special Colloquium
Dr. Daniela Doneva
Theoretische Astrophysik Eberhard-Karls-Universitat Tuebingen

Gravity models admitting scalarization are attracting considerable attention due to their natural ability to evade constraints from weak field observations. In the present talk, I will discuss one such modified theory of gravity, namely the scalar-Gauss-Bonnet gravity. It offers the possibility for spontaneous growth of scalar hair both for neutron stars and black holes with a trigger of the process being the curvature of the spacetime itself. I will discuss the sectors of the theory that have already been tested with binary pulsar observations and what is the implication on black hole scalarization. Special attention will be paid to future prospects of testing further Gauss-Bonnet gravity in terms of theory development and pulsar observations.