We present a comprehensive study of formaldehyde (H2CO)
absorption and radio recombination line (H110α) emission in
215 molecular clouds from the Bolocam Galactic Plane Survey, observed
using the Nanshan 25Â m radio telescope. H2CO was detected in
88 sources (40.93%) with 59 being new detections, while H110α
emission was found in only 11 sources (5.12%), all coincident with
H2CO absorption. There exists a correlation of
H2CO fluxes with millimeter fluxes below a \(3~\mathrm{Jy}\) threshold and an increased
dispersion above it, suggesting the sub-cosmic microwave background
cooling of H2CO. Cross-matching with kinematic distance
catalogs revealed H2CO spanning galactocentric distances from
\(0.216\) to \(10.769~\mathrm{kpc}\), with column
densities ranging from \(7.82 \times
10^{11}\) to \(6.69 \times
10^{14}~\mathrm{cm}^{-2}\). A significant inverse correlation was
observed between H2CO detection fraction and galactocentric
distance, suggesting enhanced star-forming activity closer to the
Galactic Center. These findings challenge traditional Galactic Habitable
Zone (GHZ) models by demonstrating the presence of biogenic precursors
in the inner Galaxy, shielded within dense molecular clouds. Our results
underscore the importance of incorporating chemical tracers such as
H2CO, alongside physical constraints to refine the boundaries
of the GHZ and advance the research of prebiotic chemistry in the Milky
Way.
@article{Baharin2025,title={Rethinking Habitability Using Biogenic Precursors: Formaldehyde in Millimeter Molecular Clouds of the Inner Galaxy},volume={988},issn={1538-4357},url={http://dx.doi.org/10.3847/1538-4357/add691},doi={10.3847/1538-4357/add691},number={1},journal={The Astrophysical Journal},publisher={American Astronomical Society},author={Baharin, Nursyazela Badrina and Nazri, Affan Adly and Rosli, Zulfazli and Abidin, Zamri Zainal and Tajuddin, Hairul Anuar and Esimbek, Jarken and Li, Da Lei and Tang, Xiaoke},year={2025},month=jul,pages={36},}
The RAWS Project: I. Do AGN quench their activity in cosmic filaments
at redshifts up to \(z \sim 0.6\)?
Mohd Shaiful Rizal Hassan, Zamri Zainal Abidin, and Affan Adly Nazri
Monthly Notices of the Royal Astronomical Society, Jul 2025
The role of cosmic filaments in galaxy evolution remains uncertain,
with conflicting evidence for both enhancement and suppression of star
formation (SF) and active galactic nucleus (AGN) activity. In this first
paper of the RAWS (RACS-WISE-SCOS-SDSS) project, we investigate the
radio properties of galaxies in filaments by analysing source counts of
radio sources from the Rapid ASKAP Continuum Survey (RACS),
cross-matched with data from the Wide-field Infrared Survey Explorer
(WISE), SuperCOSMOS Sky Survey (SCOS), and Sloan Digital Sky Survey
(SDSS) filament reconstructions. Two samples - RAWS-low and RAWS-mid -
were derived from RACS-low (\(887.5~\mathrm{MHz}\)) and RACS-mid (\(1367.5~\mathrm{MHz}\)), respectively. Each
sample was subdivided into (1) all RAWS galaxies, (2) RAWS filament
galaxies, and (3) RAWS non-filament galaxies. We constructed normalized
Euclidean \(1.4\mathrm{-GHz}\) source
counts for all subsamples. The results show that AGNs dominate all
samples. The source counts for subsamples (1) and (3) agree well with
those from previous radio surveys. However, we observe a clear
suppression in the source counts of filament galaxies (subsample 2)
across both RACS frequencies. This suggests a lower surface density of
AGN in filamentary environments compared to field galaxies, possibly due
to environmental processes such as ram-pressure stripping, gas
depletion, or intergalactic medium (IGM) interactions. These findings
are consistent with simulations predicting gradual quenching in
intermediate-density environments. While our results support the idea
that filaments may suppress AGN activity up to \(z \sim 0.6\), further investigation is
needed to understand their dual role in both quenching and fuelling
galaxy evolution.
@article{Hassan2025,title={The RAWS Project: I. Do AGN quench their activity in cosmic filaments at redshifts up to $z \sim 0.6$?},issn={1365-2966},url={http://dx.doi.org/10.1093/mnras/staf1209},doi={10.1093/mnras/staf1209},journal={Monthly Notices of the Royal Astronomical Society},publisher={Oxford University Press (OUP)},author={Hassan, Mohd Shaiful Rizal and Abidin, Zamri Zainal and Nazri, Affan Adly},year={2025},month=jul,pages={3696--3708},}
Temporal variability in low-frequency radio interference: Insight
from high-cadence monitoring at a candidate radio notification zone in
Malaysia
Affan Adly Nazri, Zamri Zainal Abidin, Mohamad Ridhauddin Mat Sabri, Zulfazli Rosli, Mohd Shaiful Rizal Hassan, ...
Extensive radio frequency interference (RFI) monitoring is essential in the site selection process before constructing radio astronomy observatories, followed by mitigation strategies to minimize its adverse effects. Malaysia has an enormous prospect for radio astronomy due to its prominent location in the centre of Southeast Asia, but is challenged by its relatively high population density. In this research article, we perform high-cadence, low-frequency RFI monitoring at two sites, each representing an urban and a rural environment. Using modified generalized spectral kurtosis (GSK) as an RFI detection method, we ascertain the suitability of Glami Lemi, a rural area in the centre of Peninsular Malaysia previously assigned as a candidate radio notification zone (RNZ), as a potential site for radio astronomy observations due to its lower RFI contamination in our high-cadence monitoring, especially when compared with urban areas. We identified a number of persistent and transient RFI in our dataset, associate each of them with their potential origins and, if present, characterize their temporal evolution. A few types of RFI mitigation strategies were also tested and discussed. This study lays the groundwork for Malaysia's endeavours in establishing its first research-grade radio telescope, emphasizing the importance of robust RFI detection and mitigation strategies in optimizing observational outcomes.
@article{Nazri2025,title={Temporal variability in low-frequency radio interference: Insight from high-cadence monitoring at a candidate radio notification zone in {Malaysia}},issn={0273-1177},url={http://dx.doi.org/10.1016/j.asr.2025.05.035},doi={10.1016/j.asr.2025.05.035},journal={Advances in Space Research},publisher={Elsevier BV},author={Nazri, Affan Adly and Abidin, Zamri Zainal and Mat Sabri, Mohamad Ridhauddin and Rosli, Zulfazli and Hassan, Mohd Shaiful Rizal and Mohd Radzi, Mohd Shazwan and Zulkiplee, Ahmad Najwan and Hanim Razak, Dalilah Nur Fathiah and Asmi, Norsyazwani and Ping, Jinsong and Wang, Mingyuan and Dong, Liang},year={2025},month=may,volume={76},issue={3},pages={1832--1853},}
2024
The RAdioGalaxyEnvironmentReferenceSurvey (RAGERS):
Evidence of an anisotropic distribution of submillimeter galaxies in the
4C 23.56 protocluster at \(z =
2.48\)
Dazhi Zhou, Thomas R. Greve, Bitten Gullberg, Minju M. Lee, Luca Di Mascolo, ...Affan Adly Nazri, ...
High-redshift radio(-loud) galaxies (HzRGs) are massive galaxies with
powerful radio-loud active galactic nuclei (AGNs) and serve as beacons
for protocluster identification. However, the interplay between HzRGs
and the large-scale environment remains unclear. To understand the
connection between HzRGs and the surrounding obscured star formation, we
investigated the overdensity and spatial distribution of
submillimeter-bright galaxies (SMGs) in the field of 4CÂ 23.56, a
well-known HzRG at \(z = 2.48\). We
used SCUBA-2 data (\(\sigma \sim
0.6~\mathrm{mJy}\)) to estimate the \(850~\mathrm{\mu m}\) source number counts
and examine the radial and azimuthal overdensities of the \(850~\mathrm{\mu m}\) sources in the
vicinity of the HzRG. The angular distribution of SMGs is inhomogeneous
around the HzRG 4CÂ 23.56, with fewer sources oriented along the radio
jet. We also find a significant overdensity of bright SMGs (\(S_{850} \geq 5~\mathrm{mJy}\)). Faint and
bright SMGs exhibit different spatial distributions. The former are
concentrated in the core region, while the latter prefer the outskirts
of the HzRG field. High-resolution observations show that the seven
brightest SMGs in our sample are intrinsically bright, suggesting that
the overdensity of bright SMGs is less likely due to the source
multiplicity.
@article{Zhou2024,title={The {RAdio} {Galaxy} {Environment} {Reference} {Survey} ({RAGERS}): Evidence of an anisotropic distribution of submillimeter galaxies in the {4C 23.56} protocluster at $z = 2.48$},url={https://doi.org/10.1051/0004-6361/202348500},doi={10.1051/0004-6361/202348500},journal={Astronomy \& Astrophysics},author={Zhou, Dazhi and Greve, Thomas R. and Gullberg, Bitten and Lee, Minju M. and Mascolo, Luca Di and Dicker, Simon R. and Romero, Charles E. and Chapman, Scott C. and Chen, Chian-Chou and Cornish, Thomas and Devlin, Mark J. and Ho, Luis C. and Kohno, Kotaro and Lagos, Claudia D. P. and Mason, Brian S. and Mroczkowski, Tony and Wagg, Jeff F. W. and Wang, Q. Daniel and Wang, Ran and Brinch, Malte. and Dannerbauer, Helmut and Jiang, Xue-Jian and Lauritsen, Lynge R. B. and Vijayan, Aswin P. and Vizgan, David and Wardlow, Julie L. and Sarazin, Craig L. and Sarmiento, Karen P. and Serjeant, Stephen and Bhandarkar, Tanay A. and Haridas, Saianeesh K. and Moravec, Emily and Orlowski-Scherer, John and Sievers, Jonathan L. R. and Tanaka, Ichi and Wang, Yu-Jan and Zeballos, Milagros and Laza-Ramos, Andres and Liu, Yuanqi and Hassan, Mohd Shaiful Rizal and Jwel, Abdul Kadir Md and Nazri, Affan Adly and Lim, Ming-Kang and Ibrahim, Ungku Ferwani Salwa Ungku},year={2024},month=oct,volume={690},pages={A196},}
2023
Limits of water maser kinematics: Insights from the high-mass
protostar AFGL 5142-MM1
Zulfazli Rosli, Ross A. Burns, Affan Adly Nazri, Koichiro Sugiyama, Tomoya Hirota, ...
Monthly Notices of the Royal Astronomical Society, 527(4), Dec 2023
Multi-epoch very long baseline interferometry (VLBI) observations
measure three-dimensional water maser motions in protostellar outflows,
enabling analysis of inclination and velocity. However, these analyses
assume that water masers and shock surfaces within outflows are
co-propagating. We compare VLBI data on maser-traced bow shocks in the
high-mass protostar AFGLÂ 5142-MM1, from seven epochs of archival data
from the VLBI Exploration of Radio Astrometry (VERA), obtained from 2014
April to 2015 May, and our newly conducted data from the KVN and VERA
Array (KaVA), obtained in 2016 March. We find an inconsistency between
the expected displacement of the bow shocks and the motions of
individual masers. The separation between two opposing bow shocks in
AFGL 5142-MM1 was determined to be \(337.17
\pm 0.07~\mathrm{mas}\) in the KaVA data, which is less than an
expected value of \(342.1 \pm
0.7~\mathrm{mas}\) based on extrapolation of the proper motions
of individual maser features measured by VERA. Our measurements imply
that the bow shock propagates at a velocity of \(24 \pm 3~\mathrm{km}~\mathrm{s}^{-1}\),
while the individual masing gas clumps move at an average velocity of
\(55 \pm
5~\mathrm{km}~\mathrm{s}^{-1}\); that is, the water masers are
moving in the outflow direction at double the speed at which the bow
shocks are propagating. Our results emphasize that investigations of
individual maser features are best approached using short-term
high-cadence VLBI monitoring, while long-term monitoring on timescales
comparable to the lifetimes of maser features is better suited to
tracing the overall evolution of shock surfaces. Observers should be
aware that masers and shock surfaces can move relative to each other,
and that this can affect the interpretation of protostellar
outflows.
@article{Rosli2023,title={Limits of water maser kinematics: Insights from the high-mass protostar {AFGL 5142-MM1}},volume={527},issn={1365-2966},url={http://dx.doi.org/10.1093/mnras/stad3767},doi={10.1093/mnras/stad3767},number={4},journal={Monthly Notices of the Royal Astronomical Society},publisher={Oxford University Press (OUP)},author={Rosli, Zulfazli and Burns, Ross A. and Nazri, Affan Adly and Sugiyama, Koichiro and Hirota, Tomoya and Kim, Kee-Tae and Yonekura, Yoshinori and Tie, Liu and Orosz, Gabor and Chibueze, James Okwe and Sobolev, Andrey M and Kang, Ji Hyun and Lee, Chang Won and Hwang, Jihye and Mohammad, Hafieduddin and Hashim, Norsiah and Abidin, Zamri Zainal},year={2023},month=dec,pages={10031-10037},}
2021
Fast Radio Bursts: Detection with Python Language Radio Burst
Emission Automatic Roger (PoLaR BEAR)
Fast radio bursts (FRB) are bright, broadband radio emissions with durations of milliseconds or less. These mysterious astrophysical phenomena are characterized by their frequency-dependent delay in the signal, also known as dispersion measure or DM. Almost all FRBs detected have DMs more than the contribution from the Milky Way, suggesting that they are extragalactic. The exact source of FRBs is uncertain, but most evidence seem to point towards magnetars, which are neutron stars with strong magnetic fields. Finding a larger sample of FRBs would be paramount in confirming and understanding the exact progenitor and burst mechanism for FRBs. Here, a Python program to detect FRBs in radio telescope data is developed based on BEAR. The program performs various functions, most importantly RFI mitigation, dedispersion, and matched filtering based on the likelihood statistic ratio test. The program then outputs FRB candidates which are detected in the data. The program manages to detect all FRBs in the real FRB data and generated FRB data with deviations comparable to BEAR. The program is expected to provide a simpler understanding in the FRB detection methodology.