MS: Chaoli Zhang & Jackie Ma

/MS: Chaoli Zhang & Jackie Ma

MS: Chaoli Zhang & Jackie Ma

Event Details

1st talk: Chaoli Zhang (chair: Enrico Garaldi)

Title: High Redshift Galaxy Groups As Seen by ATHENA

By 2028, it is expected that our cosmological model, which describes the
evolution of the Universe, will be tightly constrained from projects
such as the eROSITA and Euclid satellite missions. However, major
astrophysical questions related to the formation and evolution of the
largest collapsed structures, namely galaxy groups and clusters, will
remain open. ATHENA will help to answer the questions of how and when
the first galaxy groups in the Universe, massive enough to bind more
than 10^7 K gas, formed. In this work, we use a state-of-the-art SIXTE
simulator to investigate the ATHENA detection capabilities of the early
galaxy groups (1 < z < 4) by using wavelet-based detection algorithm.
The simulations take into account the main ATHENA instrumental features:
background, vignetting and PSF degradation with off-axis angle. Since
little is known about the thermo-dynamical state of such groups,
different physically motivated models are simulated and tested. Our
detailed simulations show such galaxy groups can be detected with high
probability as extended sources by ATHENA.
2nd talk: Jackie Ma (chair: Chaoli Zhang)

Title: Broadband Investigation of NVSS Rotation Measure Catalogue

The NVSS Rotation Measure (RM) Catalogue is a powerful dataset for
cosmic magnetism studies. With RM values through 37,543 sightlines north
of declination of -40 degrees at a density of about one per square
degree, it is the largest RM catalogue to date. The RM values were
determined with polarisation measurements at two frequency bands around
1400 MHz, and could be susceptible to npi-ambiguity. The authors tackled
this with (1) measured bandwidth depolarisation, and (2) RM values of
neighbouring sources. To test this algorithm, we performed the first
broadband spectro-polarimetric observations of 23 npi-ambiguity
candidates in the NVSS RM Catalogue with JVLA at L-band. We found 9
sources that suffer from npi-ambiguity in the RM Catalogue. Furthermore,
2 of our targets have polarisation below our detection limit (< 0.07%),
and their detections in the RM Catalogue (~ 0.5%) are likely linked to
off-axis polarisation leakage. We simulated the effects of such
instrumental leakage on the measured RM. In this talk, I will present
the above results.