Welcome!
Welcome to the issue 5 of the e-
MERLIN newsletter. We’re 1 year
old already! We will be publishing
e-MERLIN-related news and
science highlights, including calls
for proposals, adverts for summer
schools and links to e-MERLIN
partners like the EVN and ORP. If
you would like to contribute to the
e-MERLIN newsletter, please get
in touch at:
emerlin.support@jb.man.ac.uk !
The radio jets of NGC 1068 using
combined e-MERLIN/VLA imaging
In nearby galaxies, it is possible to resolve the radio
emission launched as jets into the interstellar medium
by active galactic nuclei when using high-resolution
interferometers such as e-MERLIN and the VLA.
NGC1068 is an archetypal Seyfert galaxy which resides
only 13 Mpc away making it an ideal source to study. It
has an active nucleus with large-scale jets that were first
discovered in the 1980s and 1990s with MERLIN and
the old VLA. However, new combined observations with
the upgraded e-MERLIN and VLA telescopes have now
enabled further study of this important source.!
User Newsletter
Issue 5 31 January 2024!
e-MERLIN/VLA image of NGC 1068
By combining the new VLA and e-
MERLIN high sensitivity data, the
image on the right was produced,
showing the full jet structure at
multiple spatial resolutions
simultaneously for the first time
(see figure above). The new
images are more sensitive than
the previous observations. They
reveal a new component, S2a,
south of the nucleus. Long-term
variability in component C that is
still unexplained and, the NE lobe
luminosity has been shown be
powerful enough to drive the
molecular outflows observed in
ALMA data. Future observations
combining ALMA, VLA and e-
MERLIN will be important for fully
understanding the jet power and
component properties in
NGC1068.!
Read the full paper here (Mutie et
al. 2024, MNRAS, Volume 527,
Issue 4, p 11756)!
Observations of a new
nearby X-ray binary
Swift J1727.8-1613 is a new
hard X-ray transient detected
with the Swift satellite. Very
rapidly it was found to be an X-
ray binary in outburst, with
fluxes of up to 3 Crab recorded.
e-MERLIN’s rapid response
mode enabled observations of
this new source soon after
discovery, with radio fluxes of
120mJy recorded - one of the
brightest X-ray binaries
observed with e-MERLIN.!
Read the full telegram here
(Williams-Baldwin et al. 2023,
ATel #16231)!
!
Next e-MERLIN data
school provisional
dates announced
After the success of our first
e-MERLIN data school in
2023, we are planning
another data school with
provisional dates now set for
13-15 May 2024. We expect
this to be a hybrid workshop,
and information will be made
available in coming weeks,
but if you are interested,
please get in touch via the e-
MERLIN support address at
the top of this newsletter. !
New insights on OH MegaMasers in
Arp 220 with MERLIN and EVN
Arp 220 is the prototypical Ultra-luminous Infra-red
galaxy, and was the first source found to harbour OH
MegaMaser (OHMM) emission. Previous works using
VLBI have managed to resolve the two nuclei in this
star-forming merging galaxy. But, observations with
resolutions at ~50 mas-scales are needed to resolve
the larger structures surrounding the nuclei. !
By combining EVN data with archival MERLIN data
from 2003, Arp 220’s intermediate resolution OHMM
emission has been uncovered for the first time. The
two nuclei are clearly resolved, with a southern ridge
also found in the continuum image. The combined
data also strengthens the argument of the foreground
masering material amplifying the background
emission as the OHMM are superimposed on top of
the background continuum emission.!
Read the full paper here (Baan et al. 2023, MNRAS,
Volume 523, Issue 4, p 5487)!
Maser emission regions in Arp 220
www.e-merlin.ac.uk
Dealing with irregular PSFs in radio
images using e-MERLIN and VLA
Deconvolution of radio astronomy images often
requires CLEAN algorithms which remove the effect of
the point spread function (PSF) from the source to
produce a restored image. However, irregular PSFs
can lead to a systematic error in the measured flux
densities. Previously this has been ignored as the
interferometers usually have well-behaved PSFs. But
future radio interferometers such as LOFAR and the
SKA will have a highly core-dominated set of
antennas, requiring this problem to be addressed. !
This work used e-MERLIN and VLA simulated data.
The combined telescope has a known irregular PSF
due to the multiple short-spacings provided by the
VLA and the handful of long-spacings from e-MERLIN.
Using this simulated data, the potential errors can be
as large as 250%, leading to significantly discrepant
flux recovery. However, some potential solutions are
suggested, such as re-weighting the data to make the
PSF more Gaussian, or, rescaling the residuals but
some additional work is needed to fully mitigate these
issues for the future observations.!
Read the full paper here (Radcliffe et al. 2024,
MNRAS, Volume 527, Issue 1, p 942)!
Improvement of PSF fitting as a function of the PSF size
Announcements
EVN Call for Proposals.
Deadline 1 February 2024.
Click here for further information!
Effelsberg Call for Proposals.
Deadline 5 February 2024.
Click here for further information!
INAF Call for Proposals
Deadline expected in March
2024. Click here for further
information!
Meetings/Workshops
SPARCS XII Bologna, Italy, 6-10
May 2024. Abstract submission
TBC. Click here for more details!
X-ray binary radio jets meeting
RAS London, UK, 10 May 2024,
Click here for more details!
AT-RASC 2024 Gran Canaria,
Spain, 19-24 May 2024.
Deadline 1 February, registration
opening early 2024. Click here
for more details!
1st Nordic Meeting on
Neutrino and Radio astronomy
Gothenburg, Sweden, 27-30
May 2024, Click here for more
details!
RAS NAM Hull, UK, 15-19 July
2024, Click here for more details!