Tidal Disruption Encores by Taeho Ryu, Rosalba Perna, Matteo Cantiello

“…Nuclear star clusters (NSCs), made up of a dense concentration of stars and the compact objects they leave behind, are ubiquitous in the central regions of galaxies surrounding the central supermassive black hole (SMBH). …”
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Nuclear Properties of Nearby Spiral Galaxies from Hubble Space Telescope NICMOS imaging and STIS Spectroscopy by Hughes, M, Axon, D, Atkinson, J, Alonso-Herrero, A, Scarlata, C, Marconi, A, Batcheldor, D, Binney, J, Capetti, A, Carollo, C, Dressel, L, Gerssen, J, Macchetto, D, Maciejewski, W, Merrifield, M, Ruiz, M, Sparks, W, Stiavelli, M, Tsvetanov, Z

“…We use the Nuker law to fit surface brightness profiles, derived from the NICMOS images, to look for nuclear star clusters and find possible extended sources in 3 of the 23 galaxies studied (13 per cent). …”

Gravitational waves and intermediate-mass black hole retention in globular clusters by Fragione, G, Ginsburg, I, Kocsis, B

“…The rates at low redshifts may be significantly higher if young massive star clusters host IMBHs. The merger rates are dominated by IMBHs with masses between 103 and 104 M⊙. …”

An old stellar population or diffuse nebular continuum emission discovered in Green Pea galaxies by Clarke, L, Scarlata, C, Mehta, V, Keel, WC, Cardamone, C, Hayes, M, Adams, N, Dickinson, H, Fortson, L, Kruk, S, Lintott, C, Simmons, B

“…Assuming that the diffuse and compact components have constant and single-burst star formation histories, respectively, the observed colors imply that the diffuse components (possibly the host galaxy of the star formation episode) have, on average, old stellar ages (>1 Gyr), while the star clusters are younger than 500 Myr. While a redder stellar component is perhaps the most plausible explanation for these results, the limitations of our current data set lead us to examine possible alternative mechanisms, particularly recombination emission processes, which are unusually prominent in systems with such strong line emission. …”

A study on the metallicity gradients in the galactic disk using open clusters by Yogesh Chandra Joshi, Deepak, Sagar Malhotra

“…We study the metallicity distribution and evolution in the galactic disk based on the largest sample of open star clusters in the galaxy. From the catalog of 1,879 open clusters in the range of galactocentric distance (RGC) from 4 to 20 kpc, we investigate the variation in metallicity in the galactic disk as functions of RGC, vertical distance (Z), and ages of the clusters. …”
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An Enhanced Massive Black Hole Occupation Fraction Predicted in Cluster Dwarf Galaxies by Michael Tremmel, Angelo Ricarte, Priyamvada Natarajan, Jillian Bellovary, Ray Sharma, Thomas R. Quinn

“…The predicted occupation fractions are remarkably consistent with those of nuclear star clusters. Across cluster and field environments, dwarf galaxies with earlier formation times are more likely to host a MBH. …”
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Nuclear properties of nearby spiral galaxies from Hubble Space Telescope NICMOS imaging and STIS spectroscopy by Hughes, M, Axon, D, Atkinson, J, Alonso-Herrero, A, Scarlata, C, Marconi, A, Batcheldor, D, Binney, J, Capetti, A, Carollo, C, Dressel, L, Gerssen, J, Macchetto, D, Maciejewski, W, Merrifield, M, Ruiz, M, Sparks, W, Stiavelli, M, Tsvetanov, Z

“…We use the Nuker law to fit surface brightness profiles, derived from the NICMOS images, to look for nuclear star clusters and find possible extended sources in three of the 23 galaxies studied (13%). …”

On the rate of black hole binary mergers in galactic nuclei due to dynamical hardening by Leigh, NWC, Geller, AM, McKernan, B, Ford, KES, Mac Low, M-M, Bellovary, J, Haiman, Z, Lyra, W, Samsing, J, O'Dowd, M, Kocsis, B, Endlich, S

“…We find two separate regimes for the efficient dynamical hardening of BHBs: (1) spherical star clusters with high central densities, low-velocity dispersions, and no significant Keplerian component and (2) migration traps in discs around SMBHs lacking any significant spherical stellar component in the vicinity of the migration trap, which is expected due to effective orbital inclination reduction of any spherical population by the disc. …”

Hidden Gems on a Ring: Infant Massive Clusters and Their Formation Timeline Unveiled by ALMA, HST, and JWST in NGC 3351 by Sun, J, He, H, Batschkun, K, Levy, RC, Emig, K, Rodríguez, MJ, Hassani, H, Leroy, AK, Schinnerer, E, Ostriker, EC, Wilson, CD, Bolatto, AD, Mills, EAC, Rosolowsky, E, Lee, JC, Dale, DA, Larson, KL, Thilker, DA, Ubeda, L, Whitmore, BC, Williams, TG, Barnes, AT, Bigiel, F, Chevance, M

“…Based on the ALMA continuum and molecular line data, as well as ancillary measurements for the HST and JWST counterparts, we identify 14 sources as infant star clusters with high stellar and/or gas masses (∼105 M ⊙), small radii (≲ 5 pc), large escape velocities (6–10 km s−1), and short freefall times (0.5–1 Myr). …”

Signatures of hierarchical mergers in black hole spin and mass distribution by Tagawa, H, Haiman, Z, Bartos, I, Kocsis, B, Omukai, K

“…A Bayesian analysis using the χeff, χp, and mchirp distributions suggests that 1g BHs have the maximum mass of ∼15–30M⊙ if the majority of mergers are of high-generation BHs (not among 1g–1g BHs), which is consistent with mergers in active galactic nucleus discs and/or nuclear star clusters, while if mergers mainly originate from globular clusters, 1g BHs are favoured to have non-zero spin magnitudes of ∼0.3. …”

Introducing TIGRESS-NCR. I. Coregulation of the Multiphase Interstellar Medium and Star Formation Rates by Chang-Goo Kim, Jeong-Gyu Kim, Munan Gong, Eve C. Ostriker

“…We use an adaptive ray-tracing method for UV radiation transfer from star clusters represented by sink particles, accounting for attenuation by dust and gas. …”
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A 1.3% Distance to M33 from Hubble Space Telescope Cepheid Photometry by Louise Breuval, Adam G. Riess, Lucas M. Macri, Siyang Li, Wenlong Yuan, Stefano Casertano, Tarini Konchady, Boris Trahin, Meredith J. Durbin, Benjamin F. Williams

“…Finally, we show that the flux contribution from star clusters hosting Cepheids in M33 does not impact the distance measurement and we find only ∼3.7% of the sample is located in (or nearby) young clusters. …”
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The Evolution of Inclined Binary Black Holes in the Disks of Active Galactic Nuclei by Alexander J. Dittmann, Adam M. Dempsey, Hui Li

“…The accretion disks that fuel active galactic nuclei (AGNs) may house numerous stars and compact objects, formed in situ or captured from nearby star clusters. Embedded neutron stars and black holes may form binaries and eventually merge, emitting gravitational waves detectable by LIGO/VIRGO. …”
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Dynamical Formation of Low-mass Merging Black Hole Binaries like GW151226 by Chatterjee, Sourav, Kalogera, Vicky, Rasio, Frederic A., Rodriguez, Carl

“…Using numerical models for star clusters spanning a wide range in ages and metallicities (Z) we study the masses of binary black holes (BBHs) produced dynamically and merging in the local universe (z lesssim 0.2). …”
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Properties and Astrophysical Implications of the 150 M ⊙ Binary Black Hole Merger GW190521 by LIGO Scientific Collaboration, Virgo Collaboration

“…We discuss the astrophysical implications of GW190521 for stellar collapse and for the possible formation of black holes in the pair-instability mass gap through various channels: via (multiple) stellar coalescences, or via hierarchical mergers of lower-mass black holes in star clusters or in active galactic nuclei. We find it to be unlikely that GW190521 is a strongly lensed signal of a lower-mass black hole binary merger. …”
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PHANGS–JWST First Results: Rapid Evolution of Star Formation in the Central Molecular Gas Ring of NGC 1365 by Eva Schinnerer, Eric Emsellem, Jonathan D. Henshaw, Daizhong Liu, Sharon E. Meidt, Miguel Querejeta, Florent Renaud, Mattia C. Sormani, Jiayi Sun, Oleg V. Egorov, Kirsten L. Larson, Adam K. Leroy, Erik Rosolowsky, Karin M. Sandstrom, T. G. Williams, Ashley. T. Barnes, F. Bigiel, Mélanie Chevance, Yixian Cao, Rupali Chandar, Daniel A. Dale, Cosima Eibensteiner, Simon C. O. Glover, Kathryn Grasha, Stephen Hannon, Hamid Hassani, Jaeyeon Kim, Ralf S. Klessen, J. M. Diederik Kruijssen, Eric J. Murphy, Justus Neumann, Hsi-An Pan, Jérôme Pety, Toshiki Saito, Sophia K. Stuber, Robin G. Treß, Antonio Usero, Elizabeth J. Watkins, Bradley C. Whitmore, PHANGS

“…The lanes host a large number of JWST-identified massive young star clusters. We find some evidence for temporal star formation evolution along the ring. …”
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GOALS-JWST: Hidden Star Formation and Extended PAH Emission in the Luminous Infrared Galaxy VV 114 by A. S. Evans, D. T. Frayer, Vassilis Charmandaris, Lee Armus, Hanae Inami, Jason Surace, Sean Linden, B. T. Soifer, Tanio Diaz-Santos, Kirsten L. Larson, Jeffrey A. Rich, Yiqing Song, Loreto Barcos-Munoz, Joseph M. Mazzarella, George C. Privon, Vivian U, Anne M. Medling, Torsten Böker, Susanne Aalto, Kazushi Iwasawa, Justin H. Howell, Paul van der Werf, Philip Appleton, Thomas Bohn, Michael J. I. Brown, Christopher C. Hayward, Shunshi Hoshioka, Francisca Kemper, Thomas Lai, David Law, Matthew A. Malkan, Jason Marshall, Eric J. Murphy, David Sanders, Sabrina Stierwalt

“…This redshift ∼0.020 merger has a western component (VV 114W) rich in optical star clusters and an eastern component (VV 114E) hosting a luminous mid-IR nucleus hidden at UV and optical wavelengths by dust lanes. …”
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A CATALOG OF X-RAY POINT SOURCES FROM TWO MEGASECONDS OF CHANDRA OBSERVATIONS OF THE GALACTIC CENTER by Muno, Michael P., Bauer, Franz E., Bandyopadhyay, R. M., Bower, Geoffrey C., Brandt, W. N., Broos, P. S., Cotera, A., Eikenberry, S. S., Garmire, Gordon P., Hyman, S. D., Kassim, N. E., Lang, C. C., Lazio, T. Joseph W., Law, J. C., Mauerhan, Jon C., Morris, M. R., Nagata, T., Nishiyama, S., Park, S., Ramìrez, S. V., Stolovy, S. R., Wijnands, R., Wang, Q. D., Wang, Z., Yusef-Zadeh, F., Baganoff, Frederick K

“…We compare the spatial distribution of X-ray sources to a model for the stellar distribution, and find 2.8σ evidence for excesses in the numbers of X-ray sources in the region of recent star formation encompassed by the Arches, Quintuplet, and Galactic center star clusters. These excess sources are also seen in the luminosity distribution of the X-ray sources, which is flatter near the Arches and Quintuplet than elsewhere in the field. …”
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Analysis of the fractional relativistic polytropic gas sphere by Mohamed S. Aboueisha, Mohamed I. Nouh, Emad A. -B. Abdel-Salam, Tarek M. Kamel, M. M. Beheary, Kamel A. K. Gadallah

“…Abstract Many stellar configurations, including white dwarfs, neutron stars, black holes, supermassive stars, and star clusters, rely on relativistic effects. The Tolman–Oppenheimer–Volkoff (TOV) equation of the polytropic gas sphere is ultimately a hydrostatic equilibrium equation developed from the general relativity framework. …”
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PHANGS–JWST First Results: Stellar-feedback-driven Excitation and Dissociation of Molecular Gas in the Starburst Ring of NGC 1365? by Daizhong Liu, Eva Schinnerer, Yixian Cao, Adam Leroy, Antonio Usero, Erik Rosolowsky, J. M. Diederik Kruijssen, Mélanie Chevance, Simon C. O. Glover, Mattia C. Sormani, Alberto D. Bolatto, Jiayi Sun, Sophia K. Stuber, Yu-Hsuan Teng, Frank Bigiel, Ivana Bešlić, Kathryn Grasha, Jonathan D. Henshaw, Ashley T. Barnes, Jakob S. den Brok, Toshiki Saito, Daniel A. Dale, Elizabeth J. Watkins, Hsi-An Pan, Ralf S. Klessen, Eric Emsellem, Gagandeep S. Anand, Sinan Deger, Oleg V. Egorov, Christopher M. Faesi, Hamid Hassani, Kirsten L. Larson, Janice C. Lee, Laura A. Lopez, Jérôme Pety, Karin Sandstrom, David A. Thilker, Bradley C. Whitmore, Thomas G. Williams

“…We compare embedded young massive star clusters (YMCs) to (sub-)millimeter line observations tracing the excitation and dissociation of molecular gas in the starburst ring of NGC 1365. …”
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