Wednesday Colloquium


"Propagation and lensing of gravitational waves in modified theories"

Sreekanth Harikumar (National Center for Nuclear Research, Warsaw)

The first direct detection of gravitational waves by LIGO collaboration has opened a new era of Gravitational Wave astronomy. The bending of light by massive objects is a prediction of General Relativity (GR) and this phenomenon known as gravitational lensing has now become an indispensable tool in astrophysics. Therefore, in this era of astronomy, the next most anticipated event is the detection of gravitational waves lensed by massive sources along the line of sight. The lensed gravitational waves has many applications such as detection of Intermediate Mass BlackHoles (IMBH), Primordial Black Holes, precision cosmology etc. Another emerging avenue is the test of GR, in this talk I will discuss the predictions of f(R) and Palatini f(R) in the context of lensing of gravitational waves.



Young astronomers meeting at CAMK (CAMK, Warsaw)


"TESS photometry of hot subdwarf stars"

Sumanta Kumar Sahoo (CAMK, Warsaw)

Hot subdwarf stars are extreme horizontal branch stars, consisting of a convective helium-burning core, helium shell, and a thin (in mass) hydrogen envelope. A few of these subdwarfs pulsate, which opens the window to study these stars using asteroseismology. The majority of such pulsating stars detected are B-type stars (sdBV). From the TESS mission, we have detected a few tens of rich gravity mode sdBVs by analyzing their short cadence (SC) light curves and identified their pulsation mode geometries. Apart from the SC data, we also extracted light curves from TESS full frame images for the targets not observed in SC mode and analyzed them to detect pulsations. I will be talking about these pulsating subdwarf stars and our study to understand their pulsation properties.



Jonas Pereira