Star Cluster Science with LSST

 
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All sessions are pitched for general (non-technical) community participants, everyone is welcome at all sessions.

The LSST will provide a unique opportunity to study a huge sample of star clusters with a wide range of properties, from young low mass clusters in the Solar Neighbourhood to the most massive old star clusters out to a redshift of z = 0.05. This session will provide a chance to discuss future LSST-related science with star clusters, with a particular focus on lessons learned from relevant precursor studies, and the challenges that still need to be addressed.  

Session Agenda 

Each talk will be 10 min (8 min + 2 min for questions).

  • N. Lodieu: A 5D map of the nearest open clusters from high-mass stars down to the substellar regime
  • R. M. Rich: Globular Clusters in the Blanco DECam Bulge Survey
  • B. Dias: The Magellanic Clouds star clusters with the VISCACHA survey
  • M. Reina-Campos: Tracing the Structure of Dark Matter Haloes Using Globular Cluster Populations: insights from the E-MOSAICS simulations
  • A. Lançon: Extragalactic Star Clusters with Euclid and LSST
  • K. Dage: The Pros and Cons of Using Machine Learning Algorithms to Find Extragalactic Globular Clusters

 

Session Abstracts

Nicolas Lodieu (Instituto de Astrofísica de Canarias)
A 5D map of the nearest open clusters from high-mass stars down to the substellar regime
We present a 5D map of four of the nearest clusters to the Sun: Alpha Persei (d~178 pc, 85 Myr), the Pleiades (d~135 pc; 125 Myr), the Hyades (d~46 pc; 650 Myr; Lodieu et al. 2019), and Praesepe (d~187 pc; 590 Myr). We identified bona-fide kinematic members from high-mass stars down to the hydrogen-burning limit and below (depending on the distance and age of the cluster) in the second data release of Gaia. We revised the physical sizes of the clusters, and inferred updated mean distances and velocities. We derive the luminosity and mass functions and compare them to the log-normal form of the Chabrier field mass function. We also looked at the 3D spatial distribution of members and produced movies of the new members in 3D space. We find that high-mass stars tend to be located in the central regions of the clusters while low-mass stars are more frequent beyond the half-mass radii. We clearly confirm the presence of a stream in the Hyades and the Pleiades. We also compare the age of these clusters, from the literature, with the ages that we obtain from a few white dwarfs belonging to the clusters (Lodieu et al. 2019a,b). I will finish with my expectation of what LSST may bring to the field of nearby open clusters.
 
R. Michael Rich (University of California, Los Angeles)
Globular Clusters in the Blanco DECam Bulge Survey
The Blanco DECam bulge Survey is a pathfinder for potential Milky Way and crowded field studies that may be undertaken by the Rubin Observatory.  BDBS spans a 200 deg. sq. footprint spanning the Southern Galactic bulge from +/-10 deg in Galactic longitude.  The field is imaged in the ugrizY passbands, including 26 known globular clusters.  We have also crossmatched our data to Gaia, giving astrometric constraints for almost all stars with i<18.  The addition of excellent data in the u band enables studies of multiple stellar populations in globular clusters that rival those done with HST, and in addition, our field of regard allows us to confirm that FSR1758 is most likely an old metal poor globular cluster, not a dwarf galaxy.  We also are unable to confirm a number of globular clusters proposed in the literature, most notably Minitti 22 lacks an evidence of a coherent CMD or proper motion vector point diagram, making the cluster unlikely to be a bona fide globular cluster.  As image quality on the Rubin Observatory is likely to exceed that of the 4m Blanco telescope, the prospects for globular cluster studies with the Rubin Observatory are bright.
 
Bruno Dias (Universidad de Tarapacá)
The Magellanic Clouds star clusters with the VISCACHA survey
The Magellanic Clouds will be covered by the LSST in great detail, and there are proposals for studying its stellar populations focusing on variability, low-surface brightness periphery etc. In this talk, I will discuss the relevance of LSST specifically for the star clusters in the Magellanic Clouds, and how LSST will complement the VISCACHA survey and other dedicated Magellanic Clouds star cluster surveys.
 
Marta Reina-Campos (McMaster University/Canadian Institute for Theoretical Astrophysics)
Tracing the Structure of Dark Matter Haloes Using Globular Cluster Populations: insights from the E-MOSAICS simulations
Stellar cluster populations in the Local Universe show a wide range in properties, suggesting that these objects form via a unique physical channel, and that their demographics are shaped by their formation and evolution in an evolving cosmic environment. This scenario links the current cluster formation sites in the disks of the the Antennae galaxies to the old globular cluster population that mostly populates the halo of the Milky Way, implying that their evolution is tightly coupled to that of their host galaxy. To understand the observed cluster populations, it has become necessary the use of numerical simulations that can model the co-formation and evolution of stellar clusters alongside their galactic environments over a Hubble time, as it has been achieved in the E-MOSAICS project (Pfeffer+2018, Kruijssen+2019, Crain+ in prep.). In this talk, I will use simulated cluster populations from a (34.4cMpc)^3 periodic volume to explore the radial distributions of massive stellar clusters in a variety of galactic environments, and I will also discuss how number surface density profiles of massive clusters trace the structure of the dark matter halo of their host galaxies (Reina-Campos+ subm.). I will show recent results that suggest that number count studies of globular clusters closely follow the shape of dark matter haloes, possibly providing a novel method to constrain the nature of dark matter. Lastly, I will summarize by discussing how these numerical predictions can be tested using future data from the LSST survey.
 
Ariane Lançon (Observatoire Astronomique Strasbourg)
Extragalactic Star Clusters with Euclid and LSST
The 1.2m telescope of the Euclid space mission will survey almost 15000 sq. degrees of the sky, providing high resolution images in a broad optical band (VIS) and in three near-infrared bands (Y, J, H). Slitless spectrophotometry in the near-IR will also be acquired. The core science program of the mission requires an excellent knowledge of the PSF and high precision photometry, as well as an extensive overlap with ground-based optical surveys - this setting will also benefit the study of extragalactic globular clusters. Their detection will be based on morphology and on colours: while Euclid will provide morphological information and precise, uniform red and near-IR photometry, the ground-based surveys such as Rubin/LSST will obtain the corresponding optical and near-UV fluxes. Coordinated efforts are needed to combine the information of the two surveys, in order to optimize both the search for globular clusters and the exploitation of the accurate energy distributions that will be measured.
 
Kristen Dage (McGill University)
The Pros and Cons of Using Machine Learning Algorithms to Find Extragalactic Globular Clusters
Extragalactic globular clusters are home to a number of exciting sources, from Ultraluminous X-ray sources to Fast Radio Bursts. Population studies of these rare events are hampered by the lack of a complete survey of extragalactic globular clusters--something that will change once the Rubin Observatory comes online. Using M87 and its well-studied globular cluster system, we are examining the pros and cons of identifying globular clusters with machine learning techniques such as neural networks and random forest classification, using data from a photometric ground-based Canada France Hawaii Telescope survey. We are training and testing the models on spectroscopically confirmed globular clusters, and then comparing the model output to human selected cluster candidates (selected both from ground-based and HST studies).

 

 

Watch the Live Recording

Organizer: 
C. Usher
Day: 
Tuesday, Aug 10
Time: 
09:00 HST - 12:00 PDT - 15:00 EDT - 19:00 UTC - 21:00 CEST - 05:00 AET +1