Podcasts about active galactic nuclei

Imagine having a little version of the cosmos living on your computer. In this week's Ep we're chatting about Active Galactic Nuclei (or AGN) with theoretical astrophysics PhD candidate, Georgia Stewart. Active Galactic Nuclei are some of the most powerful phenomena in the Universe but they also take millions of years to evolve

Supermassive black holes exist at the center of most galaxies, and modern telescopes continue to observe them at surprisingly early times in the Universe's evolution. It's difficult to understand how these black holes were able to grow so big so rapidly. But with the discovery of a low-mass supermassive black hole feasting on material at an extreme rate, seen just 1.5 billion years after the Big Bang, astronomers now have valuable new insights into the mechanisms of rapidly growing black holes in the early Universe. In this podcast, Hyewon Suh and Julia Scharwächter discuss the discovery of LID-568, a black hole that is feeding at 40 times the theoretical limit.   Bios: Rob Sparks is in the Communications, Education and Engagement group at NSF's NOIRLab in Tucson, Arizona.   Hyewon Suh's research mainly focuses on the multi-wavelength studies of Active Galactic Nuclei and their host galaxies to understand the growth of black holes in the context of galaxy evolution. While the deep, large-area extragalactic surveys have greatly enriched our knowledge of the early universe, there are several missing pieces in the understanding of the formation and the growth of supermassive black holes. She is interested in the most energetic and obscured phase of accreting black holes to explore the formation of the first accreting black holes, and to provide the crucial observational constraints on a hidden phase in the early universe.   Julia Scharwächter's main research area is the (co-)evolution of galaxies and their supermassive black holes. She is interested in studying the role of AGN feedback and the nature of black hole mass-host galaxy scaling relations. Her observational projects mostly aim at spatially resolved studies of galaxy nuclei in the nearby Universe. She uses 3D spectroscopy in the optical, near-infrared, and at millimeter wavelengths to probe the stellar and gas component in galaxies, with a special focus on gas-kinematic black hole mass measurements and gas excitation/kinematics around AGN. She is also interested in galaxy dynamics and galaxy merger simulations using N-body/SPH codes.   Links: NOIRLab Press Release: https://noirlab.edu/public/news/noirlab2427/ NOIRLab social media channels can be found at https://www.facebook.com/NOIRLabAstro https://twitter.com/NOIRLabAstro https://www.instagram.com/noirlabastro/ https://www.youtube.com/noirlabastro   We've added a new way to donate to 365 Days of Astronomy to support editing, hosting, and production costs.  Just visit: https://www.patreon.com/365DaysOfAstronomy and donate as much as you can! Share the podcast with your friends and send the Patreon link to them too!  Every bit helps! Thank you! ------------------------------------ Do go visit http://www.redbubble.com/people/CosmoQuestX/shop for cool Astronomy Cast and CosmoQuest t-shirts, coffee mugs and other awesomeness! http://cosmoquest.org/Donate This show is made possible through your donations.  Thank you! (Haven't donated? It's not too late! Just click!) ------------------------------------ The 365 Days of Astronomy Podcast is produced by the Planetary Science Institute. http://www.psi.edu Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org.

Kann rund um ein supermassereiches schwarzes Loch ein Planet entstehen? Und wenn ja, warum nennt man die Dinger dann "Blaneten"? Licht in die blanetare Dunkelheit bringt die neue Folge der Sternengeschichten. Wer den Podcast finanziell unterstützen möchte, kann das hier tun: Mit PayPal (https://www.paypal.me/florianfreistetter), Patreon (https://www.patreon.com/sternengeschichten) oder Steady (https://steadyhq.com/sternengeschichten)

This episode contains: The three spoopiest hosts on this podcast enter the month of October being just... fine? Maybe overwhelmed? Ben was a groomsman for a fancy wedding (or at least a reception, it's a long story) this last weekend, and can we just pause to say how awesome it is that people can keep a friendship alive over decades? Steven's wife is going on a wild bachelorette party cruise and it sounds like A LOT. Meanwhile, we remember the best dog, Charlie, who Steven bid farewell to last Monday. Devon has been just doing his best, nothing to report. This week in space! AI helps distinguish dark matter from cosmic noise. Only... it doesn't yet? Dark matter, the invisible force holding the universe together, is a subject of intense research. It makes up around 85% of all matter and 27% of the universe's contents. Despite decades of research, the true nature of dark matter remains a mystery. Some scientists believe that dark matter particles may occasionally interact, a phenomenon known as self-interaction. Detecting these interactions would provide crucial insights into dark matter's properties. However, distinguishing between dark matter self-interactions and active galactic nuclei (AGN) feedback has been a challenge. Astronomer David Harvey has developed a deep-learning algorithm called Inception, which can untangle complex signals and differentiate between dark matter self-interactions and AGN feedback. Inception achieved an impressive accuracy of 80% under ideal conditions (as in, pre-generated image data, not real photos), indicating its adaptability and reliability for future dark matter research. This AI-based approach could significantly impact our understanding of dark matter and help scientists analyze massive amounts of data from space. Shadows searching in the night. Let Ben introduce you to Shade Map, a layer on top of Google Maps that lets you visualize shade anywhere in the world, down to the building level, at any date and time of day. It even lets you add buildings so you can visualize what a new construction project will do to the buildings and areas around it. There's a slider that lets you change the time, and the shadows update in real time. Ben recommends using this on desktop. Also, hat tip to Tom for letting us know about Steam and Valve's battle against arbitration fees. It's not a phase! Research reveals reality of Ice Age teen puberty. New research published in the Journal of Human Evolution reveals that Ice Age teens from 25,000 years ago went through similar puberty stages as modern-day adolescents. Researchers found evidence of puberty stages in the bones of 13 ancient humans between 10 and 20 years old. The study, led by University of Victoria paleoanthropologist April Nowell, found specific markers in the bones that allowed them to assess the progress of adolescence. The technique developed by lead author Mary Lewis from the University of Reading evaluates the mineralization of canines and maturation of bones to identify the stage of puberty reached by the individual at their time of death. The research helps to humanize these teens in a way that simply studying stone tools cannot. Researchers from six institutions collaborated internationally to develop this body of knowledge. This reminds Ben of Saffron teaching neanderthals Cockney slang in episode seven of the Time Bandits television show. Devon informs Ben that Time Bandits didn't get renewed, and the world became a darker place. Book Club: Next week, we'll be reading some classic horror with Edgar Allen Poe's The Pit and the Pendulum. Get in the spirit with this live performance of The Poet and the Pendulum by Nightwish, one of Devon's favorite songs by that band. This week, it's time to discuss The Remedy by Adam Haslett from the Dark Corners collection. It's so well written! Well, until the ending, that is. Spoiler alert: we did not like this one, so much so that we're going to take a break from these Amazon originals for at least a week. Oh, and find out what you call a werewolf with a YouTube channel.

Space is full of amazing stuff we can't see with the naked eye! Join Olly and Georgia in this episode as they embark on a journey to the distant reaches of the universe with Sophie Young, a first-year PhD student in astrophysics. Sophie shares insights into her award-winning research on Active Galactic Nuclei—the powerful galaxy centres known for emitting massive jets of superheated plasma that can't be seen with the naked eye. We talk about how Sophie's passion for theoretical astrophysics and how she uses powerful supercomputers to study these cosmic jet streams.Show theme music: Kevin MacLeodHost: Olly Dove (@olly_dove) & Georgia Stewart (@georg1a_stewart)Production: Meredith Castles (@MeredithCastles)Media & Promotion: Georgia Stewart (@georg1a_stewart)

Scientific Sense ® by Gill Eapen: Dr. Anna Trindade Falcão is Postdoctoral Researcher at the Center for Astrophysics at the Smithsonian Institute of Harvard University. She is interested in multi wavelength studies of active galactic nuclei (AGN), their evolution, and connection to the interstellar medium. Please subscribe to this channel: https://www.youtube.com/c/ScientificSense?sub_confirmation=1 --- Support this podcast: https://podcasters.spotify.com/pod/show/scientificsense/support

Like just about any kid, Abhishek Desai grew up in India with dreams of becoming an astronaut. While that dream didn't come true, Desai is a NASA Postdoctoral Program Fellow studying space from Earth. His project at NASA focuses multimessenger and multiwavelength astronomy to explain processes happening inside an Active Galactic Nuclei. In this conversation with Further Together's Michael Holtz, Desai talks about coming to the United States for his education, the importance of collaboration and mentorship, the value of the NASA NPP program, and more. To learn more about the NASA Postdoctoral Program, visit https://npp.orau.org/index.html

On today's episode: It's happening… Scientists are starting to be able to read our minds! We might owe the existence of life to quasars. All that and more today on All Around Science... LINKS: Reading The Mind with fMRI and AI | Neurologica Blog QUASAR SOURCES https://en.wikipedia.org/wiki/Blazar https://www.sheffield.ac.uk/news/astronomers-solve-60-year-mystery-quasars-most-powerful-objects-universe https://www.youtube.com/watch?v=s9W5x3SMBH4&ab_channel=JoeScott https://www.sciencedaily.com/releases/2023/04/230426210530.htm https://academic.oup.com/mnras/article/522/2/1736/7035603?login=false https://webbtelescope.org/contents/articles/what-are-active-galactic-nuclei https://astronomy.swin.edu.au/cosmos/a/Active+Galactic+Nuclei#:~:text=Carl%20Seyfert%20discovered%20the%20first,very%20close%20to%20the%20nucleus THEME MUSIC by Andrew Allen https://twitter.com/KEYSwithSOUL http://andrewallenmusic.com

Join us this week for part two of our mini-series in celebration of the James Webb Space Telescope! This time around, we meet with Georgia Stewart, a PhD student at UTAS, studying Active Galactic Nuclei. These objects are used by Georgia and her colleagues to age and classify stellar and star-forming regions, as well as the black holes, central to these galaxies.Listen in as Georgia discusses her pathway into astrophysics, as well as what it means to be a young woman in the field. Show theme music: Kevin MacLeodHost: Niamh Chapman (@nchapmanTAS)Co-Host: Ryan SmithProduction: Olly Dove (@littledove440) Media & Promotion: Kate Johnson (@KatePlantPhys)

Is our universe inside a black hole? On this episode, Neil deGrasse Tyson and comic co-host Chuck Nice answer questions about wormholes, quasars, white holes, and more with astrophysicist Charles Liu. What would a wormhole look like to us? NOTE: StarTalk+ Patrons can listen to this entire episode commercial-free.Photo Credit: ESO/M. Kornmesser, CC BY 4.0, via Wikimedia Commons

Investigating Non-linear and Stochastic Hard X-ray Variability of Active Galactic Nuclei using Recurrence Analysis by R. A. Phillipson et al. on Monday 28 November We present results of recurrence analysis of 46 active galactic nuclei (AGN) using light curves from the 157-month catalog of the Swift Burst Alert Telescope (BAT) in the 14-150 keV band. We generate recurrence plots and compute recurrence plot metrics for each object. We use the surrogate data method to compare all derived recurrence-based quantities to three sets of stochastic light curves with identical power spectrum, flux distribution, or both, in order to determine the presence of determinism, non-linearity, entropy, and non-stationarity. We compare these quantities with known physical characteristics of each system, such as black hole mass, Eddington ratio, and bolometric luminosity, radio loudness, obscuration, and spectroscopic type. We find that almost all AGN in this sample exhibit substantial higher-order modes of variability than is contained in the power spectrum, with approximately half exhibiting nonlinear or non-stationary behavior. We find that Type 2 AGN are more likely to contain deterministic variability than Type 1 AGN while the same distinction is not found between obscured and unobscured AGN. The complexity of variability among Type 1 AGN is anticorrelated with Eddington ratio, while no relationship is found among Type 2 AGN. The connections between the recurrence properties and AGN class suggest that hard X-ray emission is a probe of distinct accretion processes among classes of AGN, which supports interpretations of changing-look AGN and challenges the traditional unification model that classifies AGN only on viewing angle. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.13774v1

Investigating Non-linear and Stochastic Hard X-ray Variability of Active Galactic Nuclei using Recurrence Analysis by R. A. Phillipson et al. on Sunday 27 November We present results of recurrence analysis of 46 active galactic nuclei (AGN) using light curves from the 157-month catalog of the Swift Burst Alert Telescope (BAT) in the 14-150 keV band. We generate recurrence plots and compute recurrence plot metrics for each object. We use the surrogate data method to compare all derived recurrence-based quantities to three sets of stochastic light curves with identical power spectrum, flux distribution, or both, in order to determine the presence of determinism, non-linearity, entropy, and non-stationarity. We compare these quantities with known physical characteristics of each system, such as black hole mass, Eddington ratio, and bolometric luminosity, radio loudness, obscuration, and spectroscopic type. We find that almost all AGN in this sample exhibit substantial higher-order modes of variability than is contained in the power spectrum, with approximately half exhibiting nonlinear or non-stationary behavior. We find that Type 2 AGN are more likely to contain deterministic variability than Type 1 AGN while the same distinction is not found between obscured and unobscured AGN. The complexity of variability among Type 1 AGN is anticorrelated with Eddington ratio, while no relationship is found among Type 2 AGN. The connections between the recurrence properties and AGN class suggest that hard X-ray emission is a probe of distinct accretion processes among classes of AGN, which supports interpretations of changing-look AGN and challenges the traditional unification model that classifies AGN only on viewing angle. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.13774v1

Rarefied Broad-Line Regions in Active Galactic Nuclei: Anomalous Responses in Reverberation Mapping and Implications for Weak-Emission Line Quasars by Pu Du et al. on Wednesday 23 November Reverberation mapping (RM) is a widely-used method for probing the physics of broad-line regions (BLRs) in active galactic nuclei (AGNs). There are increasing preliminary evidences that the RM behaviors of broad emission lines are influenced by BLR densities, however, the influences have not been investigated systematically from theoretical perspective. In the present paper, we adopt locally optimally emitting cloud model and use CLOUDY to obtain the one-dimensional transfer functions of the prominent UV and optical emission lines for different BLR densities. We find that the influences of BLR densities to RM behaviors have mainly three aspects. First, rarefied BLRs (with low gas densities) may show anomalous responses in RM observations. Their emission-line light curves inversely response the variations of continuum light curves, which may have been observed in some UV RM campaigns. Second, the different BLR densities in AGNs may result in correlations between the time lags and equivalent widths of emission lines, and may contribute to the scatters of the radius-luminosity relationships. Third, the variations of BLR densities may explain the changes of time lags in individual objects in different years. Some weak emission-line quasars (WLQs) are probably extreme cases of rarefied BLRs. We predict that their RM observations may show the anomalous responses. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.11966v1

Active Galactic Nuclei as potential Sources of Ultra-High Energy Cosmic Rays by Frank M. Rieger. on Wednesday 23 November Active Galactic Nuclei (AGNs) and their relativistic jets belong to the most promising class of ultra-high-energy cosmic ray (UHECR) accelerators. This compact review summarises basic experimental findings by recent instruments, and discusses possible interpretations and astrophysical constraints on source energetics. Particular attention is given to potential sites and mechanisms of UHECR acceleration in AGNs, including gap-type particle acceleration close to the black hole, as well as first-order Fermi acceleration at trans-relativistic shocks and stochastic shear particle acceleration in large-scale jets. It is argued that the last two represent the most promising mechanisms given our current understanding, and that nearby FR~I type radio galaxies provide a suitable environment for UHECR acceleration. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12202v1

Comparing hierarchical black hole mergers in star clusters and active galactic nuclei by Guo-Peng Li et al. on Tuesday 22 November Star clusters (SCs) and active galactic nuclei (AGNs) are promising sites for the occurrence of hierarchical black hole (BH) mergers. We use simple models to compare hierarchical BH mergers in two of the dynamical formation channels. We find that the primary mass distribution of hierarchical mergers in AGNs is higher than that in SCs, with the peaks of $sim$$13~M_{odot}$ and $sim$$50~M_{odot}$, respectively. The effective spin ($chi_{rm eff}$) distribution of hierarchical mergers in SCs is symmetrical around zero as expected and $sim$50% of the mergers have $|chi_{rm eff}|>0.2$. The distribution of $chi_{rm eff}$ in AGNs is narrow and prefers positive values with the peak of $chi_{rm eff}ge0.3$ due to the assistance of AGN disks. BH hierarchical growth efficiency, with at least $sim$30% of mergers being hierarchies in AGNs, is much higher than the efficiency in SCs. We argue that the majority of the hierarchical merger candidates detected by LIGO-Virgo may originate from the AGN channel. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.11150v1

Rarefied Broad-Line Regions in Active Galactic Nuclei: Anomalous Responses in Reverberation Mapping and Implications for Weak-Emission Line Quasars by Pu Du et al. on Tuesday 22 November Reverberation mapping (RM) is a widely-used method for probing the physics of broad-line regions (BLRs) in active galactic nuclei (AGNs). There are increasing preliminary evidences that the RM behaviors of broad emission lines are influenced by BLR densities, however, the influences have not been investigated systematically from theoretical perspective. In the present paper, we adopt locally optimally emitting cloud model and use CLOUDY to obtain the one-dimensional transfer functions of the prominent UV and optical emission lines for different BLR densities. We find that the influences of BLR densities to RM behaviors have mainly three aspects. First, rarefied BLRs (with low gas densities) may show anomalous responses in RM observations. Their emission-line light curves inversely response the variations of continuum light curves, which may have been observed in some UV RM campaigns. Second, the different BLR densities in AGNs may result in correlations between the time lags and equivalent widths of emission lines, and may contribute to the scatters of the radius-luminosity relationships. Third, the variations of BLR densities may explain the changes of time lags in individual objects in different years. Some weak emission-line quasars (WLQs) are probably extreme cases of rarefied BLRs. We predict that their RM observations may show the anomalous responses. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.11966v1

Dusty plasma in active galactic nuclei by Bożena Czerny et al. on Tuesday 22 November Since many years we know that dust in the form of the dusty-molecular torus is responsible for the obscuration in active galactic nuclei (AGN) at large viewing angles and thus for the classification of AGN. Recently, we gained some observational and theoretical insight into geometry of the region and the role of the dust in the dynamics of the outflow and failed winds. We will briefly touch on all these aspects, including our dust-based model (FRADO - Failed Radiatively Accelerated Dusty Outflow) of the formation of the Balmer lines in AGN. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.11022v1

Finding active galactic nuclei through Fink by Etienne Russeil et al. on Tuesday 22 November We present the Active Galactic Nuclei (AGN) classifier as currently implemented within the Fink broker. Features were built upon summary statistics of available photometric points, as well as color estimation enabled by symbolic regression. The learning stage includes an active learning loop, used to build an optimized training sample from labels reported in astronomical catalogs. Using this method to classify real alerts from the Zwicky Transient Facility (ZTF), we achieved 98.0% accuracy, 93.8% precision and 88.5% recall. We also describe the modifications necessary to enable processing data from the upcoming Vera C. Rubin Observatory Large Survey of Space and Time (LSST), and apply them to the training sample of the Extended LSST Astronomical Time-series Classification Challenge (ELAsTiCC). Results show that our designed feature space enables high performances of traditional machine learning algorithms in this binary classification task. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.10987v1

Active Galactic Nuclei as potential Sources of Ultra-High Energy Cosmic Rays by Frank M. Rieger. on Tuesday 22 November Active Galactic Nuclei (AGNs) and their relativistic jets belong to the most promising class of ultra-high-energy cosmic ray (UHECR) accelerators. This compact review summarises basic experimental findings by recent instruments, and discusses possible interpretations and astrophysical constraints on source energetics. Particular attention is given to potential sites and mechanisms of UHECR acceleration in AGNs, including gap-type particle acceleration close to the black hole, as well as first-order Fermi acceleration at trans-relativistic shocks and stochastic shear particle acceleration in large-scale jets. It is argued that the last two represent the most promising mechanisms given our current understanding, and that nearby FR~I type radio galaxies provide a suitable environment for UHECR acceleration. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12202v1

Dusty plasma in active galactic nuclei by Bożena Czerny et al. on Monday 21 November Since many years we know that dust in the form of the dusty-molecular torus is responsible for the obscuration in active galactic nuclei (AGN) at large viewing angles and thus for the classification of AGN. Recently, we gained some observational and theoretical insight into geometry of the region and the role of the dust in the dynamics of the outflow and failed winds. We will briefly touch on all these aspects, including our dust-based model (FRADO - Failed Radiatively Accelerated Dusty Outflow) of the formation of the Balmer lines in AGN. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.11022v1

Comparing hierarchical black hole mergers in star clusters and active galactic nuclei by Guo-Peng Li et al. on Monday 21 November Star clusters (SCs) and active galactic nuclei (AGNs) are promising sites for the occurrence of hierarchical black hole (BH) mergers. We use simple models to compare hierarchical BH mergers in two of the dynamical formation channels. We find that the primary mass distribution of hierarchical mergers in AGNs is higher than that in SCs, with the peaks of $sim$$13~M_{odot}$ and $sim$$50~M_{odot}$, respectively. The effective spin ($chi_{rm eff}$) distribution of hierarchical mergers in SCs is symmetrical around zero as expected and $sim$50% of the mergers have $|chi_{rm eff}|>0.2$. The distribution of $chi_{rm eff}$ in AGNs is narrow and prefers positive values with the peak of $chi_{rm eff}ge0.3$ due to the assistance of AGN disks. BH hierarchical growth efficiency, with at least $sim$30% of mergers being hierarchies in AGNs, is much higher than the efficiency in SCs. We argue that the majority of the hierarchical merger candidates detected by LIGO-Virgo may originate from the AGN channel. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.11150v1

Finding active galactic nuclei through Fink by Etienne Russeil et al. on Monday 21 November We present the Active Galactic Nuclei (AGN) classifier as currently implemented within the Fink broker. Features were built upon summary statistics of available photometric points, as well as color estimation enabled by symbolic regression. The learning stage includes an active learning loop, used to build an optimized training sample from labels reported in astronomical catalogs. Using this method to classify real alerts from the Zwicky Transient Facility (ZTF), we achieved 98.0% accuracy, 93.8% precision and 88.5% recall. We also describe the modifications necessary to enable processing data from the upcoming Vera C. Rubin Observatory Large Survey of Space and Time (LSST), and apply them to the training sample of the Extended LSST Astronomical Time-series Classification Challenge (ELAsTiCC). Results show that our designed feature space enables high performances of traditional machine learning algorithms in this binary classification task. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.10987v1

Compact jets dominate the continuum emission in low-luminosity active galactic nuclei by J. A. Fernández-Ontiveros et al. on Monday 21 November The disappearance of the accretion disc in low-luminosity active galactic nuclei (LLAGN) leaves behind a faint optical nuclear continuum whose nature has been largely debated, mainly due to serious observational limitations in the IR to UV range. We combine multi-wavelength sub-arcsecond resolution observations -- able to isolate the genuine nuclear continuum -- with nebular lines in the mid-IR, to indirectly probe the shape of the extreme UV continuum. We found that 8 of the nearest prototype LLAGN are compatible with pure compact jet emission (self-absorbed synchrotron plus the associated self-Compton component) over more than ten orders of magnitude in frequency. When compared with typical radio galaxies, the LLAGN continua show two peculiarities: $i)$ a very steep spectral slope in the IR-to-optical/UV range ($-3.7 < alpha_0 < -1.3$; $F_nu propto nu^{alpha_0}$); and $ii)$ a very high turnover frequency ($0.2-30, rm{THz}$; $1.3,rm{mm}-10,rm{mu m}$). These attributes can be explained if the synchrotron continuum is mainly dominated by thermalised particles at the jet base or corona with considerably high temperatures, whereas only a small fraction of the energy ($sim 20%$) would be distributed along the high-energy power-law tail of accelerated particles. On the other hand, the nebular gas excitation in LLAGN is in agreement with photo-ionisation from inverse Compton radiation ($alpha_{rm x} sim -0.7$), which would dominate the nuclear continuum shortwards of $sim 3000$ r{A}. Our results suggest that the LLAGN continuum can be dominated at all wavelengths by undeveloped jets, powered by a thermalised particle distribution, similar to the behaviour observed in compact jets of quiescent black hole X-ray binaries. This has important implications in the context of galaxy evolution, since LLAGN may represent a major but underestimated source of kinetic feedback in galaxies. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.09828v1

Intranight optical variability of low-mass Active Galactic Nuclei: A Pointer to blazar-like activity by Gopal-Krishna et al. on Tuesday 11 October This study aims to characterise, for the first time, intranight optical variability (INOV) of low-mass active galactic nuclei (LMAGN) which host a black hole (BH) of mass $M_{BH} sim 10^6 M_{odot}$, i.e., even less massive than the Galactic centre black hole Sgr A* and 2-3 orders of magnitude below the supermassive black holes (SMBH, $M_{BH}$ $sim$ $10^8 - 10^9 M_{odot}$) which are believed to power quasars. Thus, LMAGN are a crucial subclass of AGN filling the wide gap between SMBH and stellar-mass BHs of Galactic X-ray binaries. We have carried out a 36-session campaign of intranight optical monitoring of a well-defined, representative sample of 12 LMAGNs already detected in X-ray and radio bands. This set of LMAGN is found to exhibit INOV at a level statistically comparable to that observed for blazars (M$_{BH} gtrsim$ 10$^{8-9}$ M$_{odot}$) and for the $gamma$-ray detected Narrow-line Seyfert1 galaxies (M$_{BH}sim 10^7$ M$_{odot}$) which, too, are believed to have relativistic jets. This indicates that the blazar-level activity can even be sustained by central engines with black holes near the upper limit for Intermediate Mass Black Holes ($M_{BH}$ $sim$ $10^3 - 10^6 M_{odot}$). arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2210.05186v1

Accretion and Host-Galaxy Properties of 14 New "Changing-Look'' Active Galactic Nuclei Identified from the SDSS-V Survey by J. Wang et al. on Monday 10 October The widely accepted active galactic nucleus (AGN) paradigm has been recently challenged by the discovery of the so-called ``changing-look'' (CL) phenomenon characterized by spectral-type transitions. By comparing the SDSS-V and SDSS DR16 spectroscopic datasets, here we report the identification of 14 new CL-AGNs (redshift $z

The Fourth Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope -- Data Release 3 by The Fermi-LAT collaboration et al. on Monday 26 September An incremental version of the fourth catalog of active galactic nuclei (AGNs) detected by the Fermi-Large Area Telescope is presented. This version (4LAC-DR3) derives from the third data release of the 4FGL catalog based on 12 years of E>50 MeV gamma-ray data, where the spectral parameters, spectral energy distributions (SEDs), yearly light curves, and associations have been updated for all sources. The new reported AGNs include 587 blazar candidates and four radio galaxies. We describe the properties of the new sample and outline changes affecting the previously published one. We also introduce two new parameters in this release, namely the peak energy of the SED high-energy component and the corresponding flux. These parameters allow an assessment of the Compton dominance, the ratio of the Inverse-Compton to the synchrotron peak luminosities, without relying on X-ray data. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.12070v1

The Influence of Disk Composition on the Evolution of Stars in the Disks of Active Galactic Nuclei by Alexander J. Dittmann et al. on Tuesday 13 September Disks of gas accreting onto supermassive black holes, powering active galactic nuclei (AGN), can capture stars from nuclear star clusters or form stars in situ via gravitational instability. The density and thermal conditions of these disks can result in rapid accretion onto embedded stars, dramatically altering their evolution in comparison to stars in the interstellar medium. Theoretical models predict that, when subjected to sufficiently rapid accretion, fresh gas replenishes hydrogen in the cores of these stars as quickly as it is burned into helium, reaching a quasi-steady state. Such massive, long-lived ("immortal") stars may be capable of dramatically enriching AGN disks with helium, and would increase the helium abundance in AGN broad-line regions relative to that in the corresponding narrow-line regions and hosts. We investigate how the helium abundance of AGN disks alters the evolution of stars embedded therein. We find, in agreement with analytical arguments, that stars at a given mass are more luminous at higher helium mass fractions, and so undergo more radiation-driven mass-loss. We further find that embedded stars tend to be less massive in disks with higher helium mass fractions, and that immortal stars are less common in such disks. Thus, disk composition can alter the rates of electromagnetic and gravitational wave transients as well as further chemical enrichment by embedded stars. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.05499v1

Join us this week for part two of our mini-series in celebration of the James Webb Space Telescope! This time around, we meet with Georgia Stewart, a PhD student at UTAS, studying Active Galactic Nuclei. These objects are used by Georgia and her colleagues to age and classify stellar and star-forming regions, as well as the black holes, central to these galaxies.Listen in as Georgia discusses her pathway into astrophysics, as well as what it means to be a young woman in the field. Show theme music: Kevin MacLeodHost: Niamh Chapman (@nchapmanTAS)Co-Host: Ryan SmithProduction: Olly Dove (@littledove440) Media & Promotion: Kate Johnson (@KatePlantPhys)

It's tribble madness as Cameron discusses a classic Star Trek episode with Dr. Joe Pesce from the National Science Foundation! Dr. Joe is an astrophysicist who is primarily interested in the environments of the galaxies hosting supermassive black holes (also known as Active Galactic Nuclei). Today, in addition to his work with the NSF, Dr. Joe teaches courses in astronomy at GMU and the University of Colorado. His mission in life is to inspire more people across the world who are interested in space to deepen their connection to the cosmos. Any opinions, findings, conclusions, or recommendations presented in this session are those of Dr. Joe Pesce and do not necessarily reflect the views of the National Science Foundation. --- Airing first December 29, 1967, the trouble with Tribbles is a fan favorite, smash hit episode of Star Trek the original series (episode 15 of season 2) that was Written by animal loving David Gerrold (23 at the time) and directed by Joseph Pevney.

3C 147 is not the first object ever identified as a quasar, but it is sort of one of the first two objects ever called a quasar.

We are clumpy. (c) AGN Tori The link to the paper: https://arxiv.org/abs/2011.03851

Kathryn Ross (Astro Kat Ross) is a PhD Candidate researching Active Galactic Nuclei and galaxy evolution using the MWA Telescope at the International Centre for Radio Astronomy Research at Curtin University in Perth. She has a Bachelor of Science majoring in Physics and Mathematics and was awarded First Class Honours in Physics from the University of Sydney. She has researched stellar evolution, dark matter content of distant galaxies and the variability of supermassive black holes in the centres of galaxies. She also has experience researching the effectiveness of types of resources in teaching physics as a member of the Sydney University Physics Education Research (SUPER) Group. Kathryn has worked extensively in communicating science in a range of settings from radio and livestream videos on YouTube to presenting to crowds at the Star Gazing Live World Record attempt in May 2018. She particularly focuses on encouraging females to pursue careers in Physics and STEM and is an activist and advocate for Women In STEM. Currently, she is leading a campaign to change the NSW STEM Curriculum to include more female scientists. In this episode we talk about Space, black holes, feminism, That Speech by Julia Gillard, and the IncludeHer_Stem campaign. https://www.change.org/p/stem-courses-must-teach-more-about-contributions-of-women-in-the-fieldhttps://twitter.com/astro_katross Support this show http://supporter.acast.com/space-junk-podcast. Support this show http://supporter.acast.com/space-junk-podcast. See acast.com/privacy for privacy and opt-out information.

Dr. Erin Hicks' research focuses on galaxy evolution and the role that supermassive black holes play in shaping galaxies into what we see today. Key to explaining the significance of supermassive black holes is understanding Active Galactic Nuclei, galaxies in which a black hole is actively consuming the surrounding gas and dust. Through studying these galaxies Dr. Hicks aims to solve the mystery of how the evolution of a black hole and its galaxy are intertwined. Dr. Erin Hicks is an assistant professor in the UAA Physics & Astronomy Department and Director of UAA Planetarium & Visualization Theater. The event is held in honor of Stephen Hawking's 75 birthday.

00:00:00 - Patrick and Ryan welcome Astrophysicist Steve Healey to the show! We begin with a brief overview of what exactly astrophysics is. Steve claims that by listening to this section, you'll have completed most of a bachelors in the subject. Congrats!   00:20:15 - To celebrate your recent academic achievement, we all have a drink. In celebration, Steve uncorks some Champagne Soda, whatever the hell that is. Ryan powers through his trepidation and tries a pickleback, with whiskey from Wyoming and pickles sent in my listener Jerrold. Thanks, Jerrold! And Patrick kicks back with Back in Black from 21st Amendment Brewery.    00:31:17 - Now that we're all clear on the basics, we ask Steve to tell us about some his latest work. Which involves both the first and second sightings of an Active Galactic Nuclei. Don't worry, we make him explain it.    01:07:32 - PaleoPOWs are a lot like Active Galactic Nuclei; we're still not sure we get what the big deal is. Patrick is happy to announce a new recurring donation from John K. Ryan has a new guerrilla-style brachiolope drawing to be added to the Brachiolope Gallery from Colin D. Thanks, Colin! Ryan is also giving away a copy of the RPG Anodyne for anyone subscribed to the newsletter who would like it. Just e-mail in! (Only one copy; first come, first served.) Finally, Ryan participated in a course about podcast storytelling, if you'd like to purchase the course yourself, you can do so here at CreativeLive.     Thanks for listening and be sure to check out the Brachiolope Media Network for more great science podcasts!       Music for this week's show: Space, Full Colour - SonicPicnic (from the game Awesomenauts) Champagne Supernova - Oasis Satellite [Astronaut Remix] - Guster

Emerging from the cosmic web, galaxy clusters are the most massive gravitationally bound structures in the universe. Thought to have begun their assembly at 2 < z < 3, i.e. 10 to 11 billion years ago, clusters provide insights into the growth of large-scale structure as well as the physics that drives galaxy evolution. The redshift range 1 < z < 3 is a key epoch in their evolution. At z ∼ 1.5, elliptical galaxies start to become the dominant population in cluster cores, and star formation in spiral galaxies is being quenched. But there is also evidence for a progressive increase in the amount of star formation that occurs in galaxy cluster cores at z ≳ 1.5. To understand the dependence of the formation mechanisms of massive galaxies with environment, we must focus on clusters at relatively unexplored redshifts z > 1.5 where major assembly is in progress. The search for galaxy clusters at high redshift, so far, has been mildly successful and only a handful of clusters at z > 1.5 have been confirmed. Because this redshift range was essentially unreachable with previous instrumentation, it was dubbed a ‘redshift desert’. The work presented in this thesis has made a major contribution to this field. The Clusters Around Radio- Loud AGN (CARLA) survey, a 400 hr targeted Warm Spitzer program, observed 420 radio-loud AGN (active galactic nuclei) at 1.3 < z < 3.2 across the full sky. Extensive literature over several decades shows that powerful radio-loud AGN preferentially reside in overdense environments. From this survey, we have identified a sample of ∼ 200 galaxy cluster candidates by selecting strong overdensities of color-selected sources. By studying the luminosity function of the CARLA cluster candidates, we showed that quenching is happening much earlier in clusters around radio-loud AGN than in field galaxy samples. This suggests that our targets may well be the most massive and evolved structures known to date at z > 1.5. We also showed that radio-loud AGN reside in denser environments than similarly massive galaxies. This makes high-redshift clusters around radio-loud AGN particularly interesting as they can reveal how galaxies in the most massive dark matter halos assembled. A complementary project, HERGE (Herschel Radio Galaxy Evolution Project) observed a sample of 71 radio galaxies at 1 < z < 5 at far-IR wavelengths with the Herschel Space Observatory. Supporting data in the mid-IR, partially in the near-IR and at sub-mm wave- lengths allow to study cluster fields in more detail. A pilot project on a single field showed that we can identify cluster members and constrain their star-formation properties. These projects laid the foundation for future work, which will make a significant impact on understanding the formation of the most massive structures over several billion years.

Fulvio Melia is Professor of Physics and Astronomy at the University of Arizona, and is a member of the Theoretical Astrophysics Program. He is also the Series Editor for Theoretical Astrophysics with the University of Chicago Press. His overall research theme is the study of the physics of matter and radiation in the extreme conditions encountered near compact astrophysical objects, such as neutron stars and black holes. The main areas of current interest include the particle acceleration and radiative emission in Active Galactic Nuclei, the Galactic center, especially with regard to the massive black hole candidate Sgr A*, electron-positron plasmas near the event horizon of Cygnus X-1-like objects, and accreting neutron stars and white dwarfs in binary stellar systems. presented November 5, 2012.

Engineering Happiness (start time 05:09): You may think the key to happiness lies in money, or love, or more vacation days.  But what it really comes down to is math -- a mathematical formula, actually. At least that’s according to a recently published book, called “Engineering Happiness: A New Approach for Building a Joyful Life.” It's co-authored by two business and economics professors: Manel Baucells and Rakesh Sarin. How On Earth co-host Susan Moran interviews Dr. Sarin, a professor at UCLA. The Effects of Black Holes (start time 14:33): Active Galactic Nuclei, or AGNs for short, are vast black holes at the centers of galaxies. But as big as the AGNs are, galaxies are much, much bigger. Regardless, the AGNs do seem to hold some sway. CU-Boulder astronomer Jason Glenn is part of an international team that is beginning to sort out why, and talks with How On Earth's Jim Pullen. Hosts: Beth Bartel and Susan Moran Producer: Beth Bartel Engineer: Jim Pullen Additional contributions: Jim Pullen Executive Producer: Joel Parker Listen to the show:

The aim of this thesis is to characterize the properties of the integrated spectrum of active galactic nuclei(AGNs), such as the ubiquity of the Fe Kα emission in AGNs, the dependence of the spectral parameters(e.g. the power law photon index and the Fe Kα equivalent width etc.) on the X-ray luminosity and redshift, and mean properties (including the line profile) of the Fe Kα line which can be addressed via stacking in the source rest-frame. I selected 2646 point sources observed with XMM-Newton at high galactic latitude (|BII| > 25 degrees) and with the sum of EPIC-PN and EPIC-MOS 0.2–12 keV counts greater than 1000. Redshifts were obtained for 919 sources from the Nasa’s Extragalactic Database. In order to prepare a clean sample, I retained only reliable sources (those for which the detection and the spectral products do not show obvious problems). I also excluded sources classified as HII regions, groups/clusters, star-forming/starburst galaxies. The final sample consists of 507 AGNs. To examine the ubiquity of the Fe Kα emission in AGNs and the dependence of the spectral parameters on the X-ray luminosity and redshift, I employed the observed-frame stacking technique, in which individual source spectra were summed in the observed-frame to compute the integrated spectra in different redshift and luminosity bins over the range 0 < z < 5. Detailed analysis of these spectra used appropriately normalized background spectra and exposure time weighted response and ancillary files. I find that the narrow Fe Kα line at 6.4 keV is significantly detected up to z = 1. The line equivalent width decreases with increasing the X-ray luminosity in the 2–10 keV band (“Iwasawa-Taniguchi effect”). The anticorrelation is characterized by the relation log(EW_Fe) = (1.66 ± 0.09) + (−0.43 ± 0.07) log(LX,44), where EW_Fe is the rest-frame equivalent width of the neutral Fe Kα line in eV and LX,44 is the 2–10 keV X-ray luminosity in units of 10^44 erg/s. The equivalent width is nearly independent of redshift up to z ∼ 0.8 with an average value of 101 ± 40 (rms dispersion) eV in the luminosity range 43.5 ≤ log LX ≤ 44.5. This analysis also confirms the hardening of the spectral indices at low luminosities, implying a dependence of obscuration on luminosity. To derive the mean properties of the Fe Kα line in the source rest-frame, I refined the final sample of 507 AGNs and selected 248 AGNs with the EPIC-PN net 2–10 keV rest-frame counts ≥200 and power law photon indices in the range 1.5–2.2. I computed the integrated spectrum of these 248 AGNs in the source rest-frame using two different rest-frame stacking procedures. I carried out a detailed spectral analysis of these integrated spectra using various models comprising simple/complex continuum and Fe Kα line components. I find that the average Fe Kα line profile in our sample is best represented by a combination of a narrow and a broad line. The equivalent widths of the narrow and broad components are ∼30 eV and ∼100 eV, respectively. The broad line parameters such as its shape, equivalent width and its detection significance in the integrated spectrum of the 248 AGNs are observed to be very sensitive to the assumed continuum and adopted stacking method. However, despite having a well-defined sample with reasonable statistics (net counts ∼ 198000) in the integrated spectrum, I do not detect a clear extended red-wing, and the measured equivalent width of the broad feature is always lower than 170 eV, implying that most black holes are not maximally rotating.

Dr. Lawrence is Regius Professor of Astronomy. His research interests: Active Galactic Nuclei, Observational Cosmology, the Virtual Observatory PI for UK Infrared Deep Sky Survey (UKIDSS) Project Leader for AstroGrid.

Is our galaxy home to aliens? Well, yes, but only if you're talking about clusters of stars. We find out how the Milky Way has stolen globular clusters from other galaxies on this month's Naked Astronomy, as well as explore why our search for ET has been met with an eerie silence. Plus, news of lava channels on Mars, the youngest exoplanet ever found and your questions about gravity, the earlest elements and the evidence for the big bang. Like this podcast? Please help us by supporting the Naked Scientists

Is our galaxy home to aliens? Well, yes, but only if you're talking about clusters of stars. We find out how the Milky Way has stolen globular clusters from other galaxies on this month's Naked Astronomy, as well as explore why our search for ET has been met with an eerie silence. Plus, news of lava channels on Mars, the youngest exoplanet ever found and your questions about gravity, the earlest elements and the evidence for the big bang. Like this podcast? Please help us by supporting the Naked Scientists

Don Backer and Jill TarterJill Tarter will talk about the large survey SETI observing programs to be undertaken by our in-house team over the next decade, the SETI observing projects from external proposers that have been allocated array time during this current observing period, some recently suggested 'far out' SETI observing strategies (not all relating to the ATA), our first thoughts about beginning OpenSETI, our recent successful demonstrations with SonATA0, and our plans for moving forward towards a Software Defined Radio Telescope (SDRT).Don Backer will talk about early science with the ATA, which has focused on transient source searches, broad-band spectra of Active Galactic Nuclei objects (AGNs) and diffuse atomic hydrogen in clusters of galaxies. Exploratory observations of the linear polarization of AGNs have been done in a program that will probe intergalactic magnetic fields. A special transient source program was conducted -- the Fly's Eye -- to look for giant pulses from distant galaxies.play video