arXiv subjects

S. Shenoy

Publications and source records attributed to S. Shenoy.

At least 19 recordsLinked to original sources

arXiv2026

Fundamental differences in the X-ray accretion properties of low and high-excitation radio galaxies

We characterise the accretion rate properties of radio-detected AGN by combining deep radio and X-ray observations of the Bo\"{o}tes field. We used deep international LOFAR telescope observations to identify 2840 radio-AGN across $0.3 < z \leq 2$, divided into samples that are complete in radio luminosity. We further split this sample into four different classes: radio-quiet AGN (RQ-AGN), high-excitation radio galaxies (HERGs), and low-excitation radio galaxies (LERGs) hosted by star-forming (SF-LERGs) and quiescent galaxies (Q-LERGs). Through performing X-ray stacking, we determined the average X-ray luminosities, $L_{\rm{X, 2-10\,keV}}$ and average specific X-ray luminosities, $\lambda_{sL_{X}}$ (X-ray luminosity scaled by the stellar mass; a proxy for the accretion rate). We studied how these X-ray properties depend on radio luminosity, stellar mass, and redshift for each of the four AGN classes. We found that the LERGs, regardless of their star-formation activity, show significantly lower $L_{\rm{X, 2-10\,keV}}$ and $\lambda_{sL_{X}}$ than both HERGs and RQ-AGN across all redshifts. The average X-ray luminosities for the HERGs, RQ-AGN, and SF-LERGs typically increase with redshift, which may be associated with the increased cold gas fractions at earlier times, resulting in more enhanced black hole accretion. The average X-ray luminosities show weak-to-no correlation with radio luminosity at a given redshift, suggesting that the physical processes producing the X-ray and radio emission may not be coupled on spatial and/or temporal scales.

astro-ph.GA↗

arXiv2026

Enhancing the performance and capabilities of the MIRI instrument on JWST

MIRI, the Mid-Infrared Instrument on the James Webb Space Telescope, is the only instrument sensitive to wavelengths longward of 5 um on the observatory. In this regime, MIRI brings order-of-magnitude improvements over past instruments and missions in a wavelength range that is challenging or impossible to access from the ground. As such, MIRI occupies a unique parameter space, offering unparalleled capabilities in all areas of astrophysics, from the Solar System to the most distant galaxies in the Universe. We continue to make operational improvements to MIRI, four years into its operational lifetime, to create new observing opportunities, improve performance, and enhance its scientific return. In this paper we will describe several such improvements, and their anticipated impact on MIRI and JWST science.

astro-ph.IM↗

arXiv2026

The DESI View of the Faint Radio Source Population in LoTSS DR2

The faint radio-source population includes galaxies dominated by both star formation (SF) and active galactic nuclei (AGN), which are two key processes shaping galaxy evolution. To investigate this population, we probabilistically classified 251,413 radio sources from the second data release of the LOFAR Two-metre Sky Survey (LoTSS DR2) using spectroscopic data from the first release of the Dark Energy Spectroscopic Instrument (DESI DR1). Our classification method includes: (i) the identification of radio excess relative to SF, (ii) the Baldwin, Philips & Terlevich (BPT) diagram, (iii) a modified Mass Excitation (MEx) diagram, and (iv) the [OIII]5007 equivalent width. These are combined with Monte Carlo methods to estimate the probability that each source is a star-forming galaxy (SFG), a radio-quiet AGN (RQ AGN), or a low- or high-excitation radio galaxy (LERG or HERG), allowing various thresholds to be applied depending on science goals. Considering classifications above a 90 per cent probability threshold, we identify 68,820 SFGs, 32,288 RQ AGN, 35,210 LERGs and 3,085 HERGs, representing the largest radio sample to date with high-confidence spectroscopic classifications. Using this sample, we show with higher statistical power than previous studies that LERGs typically accrete below 1 per cent of the Eddington limit and HERGs above it. We also identify a small subset of high-accreting LERGs whose stacked spectra reveal prominent star-forming features, highlighting difficulties in interpreting their accretion properties. Our results demonstrate the power of large spectroscopic samples to characterise the radio-source population, providing a foundation for studies in the SKA era.

astro-ph.GA↗

arXiv2026

Testing and Validation of the Updated Pixel-Based Non-Linearity Calibration File for WFC3/IR

The WFC3\IR channel has an innate non-linear response to incident photons, which is corrected for in the calwf3 pipeline with the NLINFILE reference file. The 2009 solution is based on an average polynomial correction for each IR quadrant and is found to be poorly constrained at high fluence levels (e-) approaching the saturation limit. Using a variety of image types, sources, and sample sequences, we test a new pixel-based linearity correction developed by Shenoy et al. (2025). In nearly all cases, the new correction improves the linearity at fluence levels higher than 50,000 e-, with improvements up to 7% for pixels with fluences approaching the saturation limit (80,000 e-) in the last ima reads. The pixel-based solution also significantly decreases the number of cosmic rays erroneously flagged (due to non-linearity correction errors) during ramp fitting in calwf3, leading to improved photometric accuracy in the calibrated flt data and higher signal-to-noise ratios, particularly in Quad 1 (upper-left detector quadrant). Because the new solution tends to make sources brighter, we recalibrate the five HST flux standards used to compute the IR zeropoints and find a negligible impact (0.1-0.2%) on the published values by Calamida et al. (2024), smaller than the RMS dispersion (0.5%) in the observed to synthetic flux ratios for all five flux standards. The new NLINFILE 9au15283i lin.fits was delivered to CRDS in October 2025 and will be used to reprocess all WFC3/IR imaging and grism observations in the MAST archive. An updated reference file a2412448i lin.fits was delivered in February 2026, improving the results at the highest fluence levels by a few tenths of a percent. Please consult the Addendum for details.

astro-ph.IM↗

arXiv2025

The LOFAR Two-metre Sky Survey Deep Fields: new probabilistic spectroscopic classifications and the accretion rates of radio galaxies

The faint radio-source population includes sources dominated both by star formation and active galactic nuclei (AGN), encoding the evolution of activity in the Universe. To investigate its nature, we probabilistically classified 4,471 radio sources at z < 0.947 using low-frequency radio data from the LoTSS Deep Fields alongside a multi-component model for nebular emission, sampled by spectra obtained with the Dark Energy Spectroscopic Instrument (DESI). This was done by combining three tools: (i) the identification of a radio excess, (ii) the BPT diagram, and (iii) a modified Mass Excitation diagram, alongside Monte Carlo methods to estimate the probability that each source is either a star-forming galaxy (SFG), a radio-quiet AGN (RQ AGN), or a high-\low-excitation radio galaxy (HERG or LERG). This approach extends the probabilistic classification framework of previous works by nearly doubling the redshift range, such that we can now probabilistically classify sources over the latter half of cosmic history. Often regarded as the 'gold standard' method, spectroscopic classifications allow us to evaluate the performance of other methods. Using a 90 per cent reliability threshold, we find reasonable overall agreement (~77 per cent) with state-of-the-art photometric classifications, but significant differences remain, including that we identify 2-5 times more RQ AGN. Furthermore, our high-confidence spectroscopic classifications show that radiatively-efficient and inefficient AGN exhibit clearly distinct Eddington-scaled accretion rate distributions, contrary to recent findings in the literature. Overall, our results highlight the need for new and forthcoming spectroscopic campaigns targeting radio sources, on the pathway to the SKA.

astro-ph.GA↗

arXiv2025

A novel Bayesian approach for decomposing the radio emission of quasars: II. Link between quasar radio emission and black hole mass

Whether the mass of supermassive black hole ($M_\mathrm{BH}$) is directly linked to the quasar radio luminosity remains a long-debated issue, and understanding the role of $M_\mathrm{BH}$ in the evolution of quasars is pivotal to unveiling the mechanism of AGN feedback. In this work, based on a two-component Bayesian model, we examine how $M_\mathrm{BH}$ affects the radio emission from quasars, separating the contributions from host galaxy star formation (SF) and AGN activity. By modelling the radio flux density distribution of Sloan Digital Sky Survey (SDSS) quasars from the LOFAR Two-metre Sky Survey Data Release 2, we find no correlation between $M_\mathrm{BH}$ and SF rate (SFR) at any mass for quasars at a given redshift and bolometric luminosity. The same holds for AGN activity across most $M_\mathrm{BH}$ values; however, quasars with the top 20\% most massive SMBHs are 2 to 3 times more likely to host strong radio jets than those with lower-mass SMBHs at similar redshift and luminosity. We suggest defining radio quasar populations by their AGN and SF contributions instead of radio loudness; our new definition unifies previously divergent observational results on the role of $M_\mathrm{BH}$ in quasar radio emissions. We further demonstrate that this radio enhancement in quasars with the 20\% most massive SMBHs affects only the $\sim5\%$ most radio bright quasars at a given redshift and bolometric luminosity. We discuss possible physical origins of this radio excess in the most massive and radio-bright quasar population, which remains an interest for future study.

astro-ph.GA↗

arXiv2024

WEAVE First Light Observations: Origin and Dynamics of the Shock Front in Stephan's Quintet

We present a detailed study of the large-scale shock front in Stephan's Quintet, a byproduct of past and ongoing interactions. Using integral-field spectroscopy from the new William Herschel Telescope Enhanced Area Velocity Explorer (WEAVE), recent 144 MHz observations from the LOFAR Two-metre Sky Survey (LoTSS), and archival data from the Very Large Array and James Webb Space Telescope (JWST), we obtain new measurements of key shock properties and determine its impact on the system. Harnessing the WEAVE large integral field unit's (LIFU) field of view (90 $\times$ 78 arcsec$^{2}$), spectral resolution ($R\sim2500$) and continuous wavelength coverage across the optical band, we perform robust emission line modeling and dynamically locate the shock within the multi-phase intergalactic medium (IGM) with higher precision than previously possible. The shocking of the cold gas phase is hypersonic, and comparisons with shock models show that it can readily account for the observed emission line ratios. In contrast, we demonstrate that the shock is relatively weak in the hot plasma visible in X-rays (with Mach number of $\mathcal{M} \sim 2 - 4$), making it inefficient at producing the relativistic particles needed to explain the observed synchrotron emission. Instead, we propose that it has led to an adiabatic compression of the medium, which has increased the radio luminosity ten-fold. Comparison of the Balmer line-derived extinction map with the molecular gas and hot dust observed with JWST suggests that pre-existing dust may have survived the collision, allowing the condensation of H$_{2}$ - a key channel for dissipating the shock energy.

astro-ph.GA↗

arXiv2024

The LOFAR Two Metre Sky Survey Data Release 2: Probabilistic Spectral Source Classifications and Faint Radio Source Demographics

We present an analysis of 152,355 radio sources identified in the second data release of the LOFAR Two Metre Sky Survey (LoTSS-DR2) with Sloan Digital Sky Survey (SDSS) spectroscopic redshifts in the range 0.00 < z < 0.57. Using Monte Carlo simulations we determine the reliability of each source exhibiting an excess in radio luminosity relative to that predicted from their Ha emission, and, for a subset of 124,023 sources we combine this measurement with a full BPT analysis. Using these two independent diagnostics we determine the reliability of each source hosting a supermassive black hole of high or low Eddington-scaled accretion rate, and combine the measurements to determine the reliability of sources belonging to each of four physical classes of objects: star forming galaxies (SFGs), radio-quiet active galactic nuclei (RQAGN), and high- or low-excitation radio galaxies (HERGs or emission-line LERGs). The result is a catalogue which enables user-defined samples of radio sources with a reliability threshold suited to their science goal e.g. prioritising purity or completeness. Here we select high-confidence samples of radio sources (>90% reliability) to report: 38,588 radio-excess AGN in the LoTSS DR2 sample (362 HERGs, and 12,648 emission-line LERGs), together with 38,729 SFGs, and 18,726 RQAGN. We validate these results through comparison to literature using independent emission-line measurements, and to widely-adopted WISE photometric selection techniques. While our use of SDSS spectroscopy limits our current analysis to ~4 percent of the LoTSS-DR2 catalogue, our method is directly applicable to data from the forthcoming WEAVE-LOFAR survey which will obtain over a million spectra of 144 MHz selected sources.

astro-ph.GA↗

arXiv2024

Exploring the radio-loudness of SDSS quasars with spectral stacking

We use new 144 MHz observations over 5634 deg$^2$ from the LOFAR Two-metre Sky Survey (LoTSS) to compile the largest sample of uniformly-selected, spectroscopically-confirmed quasars from the 14th data release of the Sloan Digital Sky Survey (SDSS-DR14). Using the classical definition of radio-loudness, $R=\log(L_{\rm{1.4GHz}}/L_{i})$, we identify 3,697 radio-loud (RL) and 111,132 radio-quiet (RQ) sources at $0.6<z<3.4$. To study their properties, we develop a new rest-frame spectral stacking algorithm, designed with forthcoming massively-multiplexed spectroscopic surveys in mind, and use it to create high signal-to-noise composite spectra of each class, matched in redshift and absolute $i$-band magnitude. We show that RL quasars have redder continuum and enhanced [OII] emission than their RQ counterparts. These results persist when additionally matching in black hole mass, suggesting that this parameter is not the defining factor in making a QSO radio-loud. We find that these features are not gradually varying as a function of radio-loudness but are maintained even when probing deeper into the RQ population, indicating that a clear-cut division in radio-loudness is not apparent. Upon examining the star formation rates (SFRs) inferred from the [OII] emission line, with the contribution from AGN removed using the [NeV] line, we find that RL quasars have a significant excess of star-formation relative to RQ quasars out to $z=1.9$ at least. Given our findings, we suggest that radio-loud sources either preferably reside in gas-rich systems with rapidly-spinning black holes, or represent an earlier obscured phase of QSO evolution.

astro-ph.GA↗

arXiv2017

Simultaneous multicolour optical and near-IR transit photometry of GJ 1214b with SOFIA

The benchmark exoplanet GJ 1214b is one of the best studied transiting planets in the transition zone between rocky Earth-sized planets and gas or ice giants. This class of super-Earth/mini-Neptune planets is unknown in our Solar System, yet is one of the most frequently detected classes of exoplanets. Understanding the transition from rocky to gaseous planets is a crucial step in the exploration of extrasolar planetary systems, in particular with regard to the potential habitability of this class of planets. GJ 1214b has already been studied in detail from various platforms at many different wavelengths. Our airborne observations with SOFIA add information in the Paschen-alpha cont. 1.9 micron infrared wavelength band, which is not accessible by any other current ground- or space-based instrument due to telluric absorption or limited spectral coverage. We used FLIPO and FPI+ on SOFIA to comprehensively analyse the transmission signal of the possible water-world GJ 1214b through photometric observations during transit in three optical and one infrared channels. We present four simultaneous light curves and corresponding transit depths in three optical and one infrared channel, which we compare to previous observations and state-of-the-art synthetic atmospheric models of GJ 1214b. The final precision in transit depth is between 1.5 and 2.5 times the theoretical photon noise limit, not sensitive enough to constrain the theoretical models any better than previous observations. This is the first exoplanet observation with SOFIA that uses its full set of instruments available to exoplanet spectrophotometry. Therefore we use these results to evaluate SOFIA's potential in this field and suggest future improvements.

astro-ph.EP↗

arXiv2015

The Spitzer Archival Far-InfraRed Extragalactic Survey

We present the Spitzer Archival Far-InfraRed Extragalactic Survey (SAFIRES). This program produces refined mosaics and source lists for all far-infrared extragalactic data taken during the more than six years of the cryogenic operation of the Spitzer Space Telescope. The SAFIRES products consist of far-infrared data in two wavelength bands (70 um and 160 um) across approximately 180 square degrees of sky, with source lists containing far-infrared fluxes for almost 40,000 extragalactic point sources. Thus, SAFIRES provides a large, robust archival far-infrared data set suitable for many scientific goals.

astro-ph.GA↗

arXiv2014

Overview of the SOFIA Data Processing System: A generalized system for manual and automatic data processing at the SOFIA Science Center

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne astronomical observatory comprised of a 2.5-meter telescope mounted in the aft section of a Boeing 747SP aircraft. During routine operations, several instruments will be available to the astronomical community including cameras and spectrographs in the near- to far-IR. Raw data obtained in-flight require a significant amount of processing to correct for background emission (from both the telescope and atmosphere), remove instrumental artifacts, correct for atmospheric absorption, and apply both wavelength and flux calibration. In general, this processing is highly specific to the instrument and telescope. In order to maximize the scientific output of the observatory, the SOFIA Science Center must provide these post-processed data sets to Guest Investigators in a timely manner. To meet this requirement, we have designed and built the SOFIA Data Processing System (DPS): an in-house set of tools and services that can be used in both automatic ("pipeline") and manual modes to process data from a variety of instruments. Here we present an overview of the DPS concepts and architecture, as well as operational results from the first two SOFIA observing cycles (2013--2014).

astro-ph.IM↗

arXiv2013

Far-Infrared Properties of Type 1 Quasars

We use the Spitzer Space Telescope Enhanced Imaging Products (SEIP) and the Spitzer Archival Far-InfraRed Extragalactic Survey (SAFIRES) to study the spectral energy distributions of spectroscopically confirmed type 1 quasars selected from the Sloan Digital Sky Survey (SDSS). By combining the Spitzer and SDSS data with the 2-Micron All Sky Survey (2MASS) we are able to construct a statistically robust rest-frame 0.1-100 micron type 1 quasar template. We find the quasar population is well-described by a single power-law SED at wavelengths less than 20 microns, in good agreement with previous work. However, at longer wavelengths we find a significant excess in infrared luminosity above an extrapolated power-law, along with signifiant object-to-object dispersion in the SED. The mean excess reaches a maximum of 0.8 dex at rest-frame wavelengths near 100 microns.

astro-ph.CO↗

arXiv2012

The G305 star-forming complex: Embedded Massive Star Formation Discovered by Herschel Hi-GAL

We present a Herschel far-infrared study towards the rich massive star- forming complex G305, utilising PACS 70, 160 μm and SPIRE 250, 350, and 500 μm observations from the Hi-GAL survey of the Galactic plane. The focus of this study is to identify the embedded massive star-forming population within G305, by combining far-infrared data with radio continuum, H2O maser, methanol maser, MIPS, and Red MSX Source survey data available from previous studies. By applying a frequentist technique we are able to identify a sample of the most likely associations within our multi-wavelength dataset, that can then be identified from the derived properties obtained from fitted spectral energy distributions (SEDs). By SED modelling using both a simple modified blackbody and fitting to a comprehensive grid of model SEDs, some 16 candidate associations are identified as embedded massive star-forming regions. We derive a two-selection colour criterion from this sample of log(F70/F500)\geq 1 and log(F160/F350)\geq 1.6 to identify an additional 31 embedded massive star candidates with no associated star-formation tracers. Using this result we can build a picture of the present day star-formation of the complex, and by extrapolating an initial mass function, suggest a current population of \approx 2 \times 10^4 young stellar objects (YSOs) present, corresponding to a star formation rate (SFR) of 0.01-0.02 M\odot yr^-1. Comparing this resolved star formation rate, to extragalactic star formation rate tracers (based on the Kennicutt-Schmidt relation), we find the star formation activity is underestimated by a factor of \geq 2 in comparison to the SFR derived from the YSO population.

astro-ph.GA↗

arXiv2012

A multi-wavelength investigation of RCW175: an HII region harboring spinning dust emission

Using infrared, radio continuum and spectral observations, we performed a detailed investigation of the HII region RCW175. We determined that RCW175, which actually consists of two separate HII regions, G29.1-0.7 and G29.0-0.6, is located at a distance of 3.2+/-0.2 kpc. Based on the observations we infer that the more compact G29.0-0.6 is less evolved than G29.1-0.7 and was possibly produced as a result of the expansion of G29.1-0.7 into the surrounding interstellar medium. We compute a star formation rate for RCW175 of (12.6+/-1.9)x10^{-5} M_{\sun}/yr, and identified 6 possible young stellar object candidates within its vicinity. Additionally, we estimate that RCW175 contains a total dust mass of 215+/-53 M_{\sun}. RCW175 has previously been identified as a source of anomalous microwave emission (AME), an excess of emission at cm wavelengths often attributed to electric dipole radiation from the smallest dust grains. We find that the AME previously detected in RCW175 is not correlated with the smallest dust grains (polycyclic aromatic hydrocarbons or small carbonaceous dust grains), but rather with the exciting radiation field within the region. This is a similar result to that found in the Perseus molecular cloud, another region which harbors AME, suggesting that the radiation field may play a pivotal role in the production of this new Galactic emission mechanism. Finally, we suggest that these observations may hint at the importance of understanding the role played by the major gas ions in spinning dust models.

astro-ph.GA↗

arXiv2011

Spitzer characterisation of dust in an anomalous emission region: the Perseus cloud

Anomalous microwave emission is known to exist in the Perseus cloud. One of the most promising candidates to explain this excess of emission is electric dipole radiation from rapidly rotating very small dust grains, commonly referred to as spinning dust. Photometric data obtained with the Spitzer Space Telescope have been reprocessed and used in conjunction with the dust emission model DUSTEM to characterise the properties of the dust within the cloud. This analysis has allowed us to constrain spatial variations in the strength of the interstellar radiation field ($χ_\mathrm{ISRF}$), the mass abundances of the PAHs and VSGs relative to the BGs (Y$_\mathrm{PAH}$ and Y$_\mathrm{VSG}$), the column density of hydrogen (N$_\mathrm{H}$) and the equilibrium dust temperature (T$_\mathrm{dust}$). The parameter maps of Y$_\mathrm{PAH}$, Y$_\mathrm{VSG}$ and $χ_\mathrm{ISRF}$ are the first of their kind to be produced for the Perseus cloud, and we used these maps to investigate the physical conditions in which anomalous emission is observed. We find that in regions of anomalous emission the strength of the ISRF, and consequently the equilibrium temperature of the dust, is enhanced while there is no significant variation in the abundances of the PAHs and the VSGs or the column density of hydrogen. We interpret these results as an indication that the enhancement in $χ_\mathrm{ISRF}$ might be affecting the properties of the small stochastically heated dust grains resulting in an increase in the spinning dust emission observed at 33 GHz. This is the first time that such an investigation has been performed, and we believe that this type of analysis creates a new perspective in the field of anomalous emission studies, and represents a powerful new tool for constraining spinning dust models.

astro-ph.GA↗

arXiv2011

Tracing the Energetics and Evolution of Dust with Spitzer: a Chapter in the History of the Eagle Nebula

The Spitzer GLIMPSE and MIPSGAL surveys have revealed a wealth of details of the Galactic plane. We use them to study the energetics and dust properties of M16, one of the best known SFR. We present MIPSGAL observations of M16 at 24 and 70 $μ$m and combine them with previous IR data. The MIR image shows a shell inside the molecular borders of the nebula. The morphologies at 24 and 70 $μ$m are different, and its color ratio is unusually warm. The FIR image resembles the one at 8 $μ$m that enhances the molecular cloud. We measure IR SEDs within the shell and the PDRs. We use the DUSTEM model to fit the SEDs and constrain dust temperature, dust size distribution, and ISRF intensity relative to that provided by the star cluster NGC6611. Within the PDRs, the dust temperature, the dust size distribution, and the ISRF intensity are in agreement with expectations. Within the shell, the dust is hotter and an ISRF larger than that provided by NGC6611 is required. We quantify two solutions. (1) The size distribution of the dust in the shell is not that of interstellar dust. (2) The dust emission arises from a hot plasma where UV and collisions with electrons contribute to the heating. We suggest two interpretations for the shell. (1) The shell matter is supplied by photo-evaporative flows arising from dense gas exposed to ionized radiation. The flows renew the shell matter as it is pushed by the stellar winds. Within this scenario, we conclude that massive SFR such as M16 have a major impact on the carbon dust size distribution. The grinding of the carbon dust could result from shattering in collisions within shocks driven by the interaction between the winds and the shell. (2) We consider a scenario where the shell is a SNR. We would be witnessing a specific time in the evolution of the SNR where the plasma pressure and temperature would be such that the SNR cools through dust emission.

astro-ph.GA↗

arXiv2010

Young Stellar Objects and Triggered Star Formation in the Vulpecula OB Association

The Vulpecula OB association, VulOB1, is a region of active star formation located in the Galactic plane at 2.3 kpc from the Sun. Previous studies suggest that sequential star formation is propagating along this 100 pc long molecular complex. In this paper, we use Spitzer MIPSGAL and GLIMPSE data to reconstruct the star formation history of VulOB1, and search for signatures of past triggering events. We make a census of Young Stellar Objects (YSO) in VulOB1 based on IR color and magnitude criteria, and we rely on the properties and nature of these YSOs to trace recent episodes of massive star formation. We find 856 YSO candidates, and show that the evolutionary stage of the YSO population in VulOB1 is rather homogeneous - ruling out the scenario of propagating star formation. We estimate the current star formation efficiency to be ~8 %. We also report the discovery of a dozen pillar-like structures, which are confirmed to be sites of small scale triggered star formation.

astro-ph.GA↗