Astronomy Seminars at CFHT
May 09, 2018, at
Przemek Mroz (Astronomical Observatory of the University of Warsaw)
"Exploring the free-floating planet population with the OGLE data"
Abstract: Theories of planet formation predict the existence of a population of unbound (free-floating) planets. Gravitational microlensing provides a unique tool for studying these objects. The first results of Sumi et al. (2011) claimed that Jupiter-mass free-floating planets are as common as main-sequence stars. However, these results appear to disagree with censuses of substellar objects in young clusters and star-forming regions and with predictions of planet formation theories. I will present new results of the analysis of a ten times larger sample of microlensing events discovered by the OGLE-IV survey during the years 2010-2015. They shed new light on the population of free-floating planets.
May 01, 2018, at
Ismael Moumen (Laval University)
"A serendipitous discovery of a sample of Supernova Remnants in NGC 3344 with SITELLE"
Abstract: I present a 3D spectroscopic study of the nearby spiral galaxy NGC 3344. In particular, I will present the new sample of extragalactic Supernova Remnants (SNRs) recently discovered in the NGC 3344. Using the high spectral and spatial resolution data, obtained with the CFHT imaging spectrograph SITELLE, we identified a sample of SNR candidates by the well-known criteria [SII]/H_alpha > 0.4. Emission lines of [OII]3727, Hb, [OIII]4959,5007, Ha, [NII]6549,6584 and [SII]6717,6731 have been measured to study the ionized gas properties in the SNR candidates. Our analysis with SITELLE confirmed, with optical spectroscopy, the shock-excited nature of these sources. The question of the optimal background subtraction will be presented.
April 03, 2018, at
Kim-Vy Tran (University of New South Wales, Texas A & M University)
"From the FOURGE to the FIRE: Tracking Galaxy Evolution Over 12 Billion Years"
Abstract:ZFOURGE and ZFIRE are deep observational surveys that track how galaxies assemble over cosmic time. ZFOURGE identifies approximately 70,000 objects up to redshifts of z~7 using a custom set of near-infrared imaging filters that provide high precision photometric redshifts. ZFIRE selects galaxies from ZFOURGE for spectroscopic follow-up to measure how baryons cycle between stars, winds, and the Inter-Stellar Medium (ISM) at z~2. Here I highlight results that include building a library of composite Spectral Energy Distributions and properties of galaxies in clusters at z~2.
March 22, 2018, at
Carmelle Robert and Laurent Drissen (Universite de Laval)
"Some of the things we have done: Do ghost have hearts? and other stories"
It's almost time to head back home, so we would like to present an overview of some of the projects on which we have worked
during our 7 months sabbatical leave at UH-Hilo and CFHT, all of which involving SITELLE (with a little help from
our friend, ESPaDOnS): a well-hidden HII region inside a dusty star-forming region, and its accompanying young stars;
an expanding, old supernova remnant in the Milky way; a survey of the nearby galaxy M33; a rotation curve in a lopsided
spiral galaxy from absorption features; and star-forming galaxies 3 billion light-years away.
March 15, 2018, at
Eilat Glikman (Middlebury College)
"Dust-Reddened Quasars: Signposts for Feedback and co-evolution
Abstract: The study of the evolution of quasars and their influence on their host galaxies provides unique insight into how supermassive black holes became a ubiquitous feature of galaxies today. Dust-reddened quasars appear to represent a transitional phase in merger-driven models of quasar/galaxy co-evolution. I will present results from recent and ongoing surveys to identify these transitional systems using infrared and radio selection. The results of these surveys reveal that red quasars are among the most intrinsically-luminous quasars in the Universe, and make up ~20% of the overall quasar population. They reside in actively merging galaxies, and their rest-frame UV spectra exhibit outflows in absorption and emission. I will discuss how reddened quasars fit into the larger picture of AGN evolution which includes both mergers and secular growth. Finally, I will present new work on surveys to explore red-quasars’ parameter space to fully understand the connection between galaxy mergers and black hole growth.
February 21, 2018, at
Claire Moutou (CFHT)
"Radial velocities and exoplanets"
Abstract: This is a review or radial-velocity observing technics and developments in the last 30 years of explanet searches. I will also review the general characteristics of exoplants found using the radial-velocity method, and discuss recent discoveries.
February 12, 2018, at
Jean-Charles Cuillandre (Institut de Recherche sur les lois Fondamentales de l'Univers
Abstract: The ESA Euclid space mission core science goals rely on complementary deep ground-based surveys covering both the northern and southern galactic caps. This talk will present an overview of the space survey design and the current status of the ground-based survey campaign, with a focus on its forerunner, CFHT's Canada-France Imaging Survey.
"The challenge of the distributed Euclid survey"
January 24, 2018, at
Haeun Chung (Seoul National University/Korea Institute for Advanced Study)
Abstract: Devasthal Optical Telescope Integral Field Spectrograph (DOTIFS) is a new multi-Integral Field Unit (IFU) instrument being designed and fabricated by the Inter-University Center for Astronomy and Astrophysics (IUCAA), Pune, India, for the Cassegrain side port of the 3.6m Devasthal Optical Telescope, operated by the Aryabhatta Research Institute of Observational Sciences (ARIES). The science drivers mainly focus on nearby galaxies, which are the primary targets of the instrument. This includes star formation and kinematics of nearby galaxies, galactic HII regions, merging and interacting galaxies, etc. DOTIFS has sixteen IFUs, which can be deployed over an 8 arcminute diameter telescope focal plane. Each IFU sees 8.7 arcsec x 7.4 arcsec on the sky and is composed of a 12 x 12 array of hexagonal shape microlenses each of which is 0.8 arcsec vertex to vertex. Optical fibers are attached to the back side of each microlens to gather and transfer light to the spectrographs. Eight identical, all refractive, dedicated spectrographs cover 2,304 fibers, with 288 fibers (from two IFUs) per spectrograph. Its wavelength coverage is 370-740nm, and the spectral resolution is 1200 â 2400 over the wavelength range. In this talk, I will present an overview and current development status of the instrument.
"DOTIFS: a new multi-IFU optical spectrograph for the 3.6-m Devasthal optical telescope - overview and development status"
January 23, 2018, at
Lauren Weiss (Trottier Postdoctoral Fellow
Institute of Research on Exoplanets
Universite de Montreal)
Abstract: The universe has provided us with multiplanet systems, laboratories in which we can test the physics of planet formation. I will talk about three ways in which we can use multiplanet systems as laboratories. (1) We can study the orbital dynamics of a single multi-planet system in detail. (2) In each multiplanet system, we can compare a planet to its siblings, developing statistics over many systems. (3) We can compare multiplanet systems to systems with only one known planet. My talk will draw on results from the California Kepler Survey, which provided new stellar and planetary properties for 909 transiting planets in 355 multiplanet systems, as well as recent dynamical work.
"Multi-Planet Systems as Laboratories for Planet Formation"
December 8, 2017, at
Michael Radica (McMaster University)
Abstract: My talk will elaborate on the two main projects I have worked on during my time at the CFHT.
I will first discuss the problems encountered with the ORCS data reduction pipeline for SITELLE. Its
software was updated to version 2 in early September, which introduced issues in optimization of the
spectral line fitting procedure. I will speak about our attempts to isolate and fix the problem. The
second part of the talk will focus on my main project - to better understand the line of sight
variations in dust extinction, in the direction of NGC 6822. We have both high resolution spectroscopy,
as well as visible and infrared photometry, from SITELLE and WIRCam, for NGC 6822. In conjunction, our
photometry and spectroscopy can allow us to derive line of sight dust extinction laws for NGC 6822,
and identify how the individual line of sight laws vary from the mean diffuse dust extinction law,
commonly used to correct for dust in the Milky Way,
"A High Resolution Study of NGC 6822 with SITELLE"
November,17 2017, at
Erini Lambrides (John Hopkins University)
Abstract:Most galaxies appear to harbor a supermassive black hole (SMBH) at their centers. The growing
SMBH and their immediate neighborhoods appear as compact but highly luminous nuclei known Active
Galactic Nuclei (AGN). In this talk we present our efforts to disentangle the impact of AGN on the
interstellar medium of their host galaxies. We analyze 2200 mid-infrared spectra of active galaxies to
determine if and how accreting, super-massive black holes at the center of galaxies impact the
interstellar medium of their hosts. The molecular gas component of the interstellar medium is important
because it is the fuel for both star-formation and SMBH accretion. We provide a large census of
rotational molecular hydrogen emission in the context mid-infrared star-formation and AGN activity
diagnostics. We find a 200K difference between the excitation temperatures of the higher pure rotational
molecular hydrogen transitions in AGN dominated and non-AGN dominated spectra. We find a statistically
significant positive correlation between excess molecular hydrogen emission and the relative
contribution of the AGN to the IR emission. We also perform a census of polycyclic aromatic hydrocarbon
emission, and find that dust grains in AGN dominated galaxies appear have a wider size of ranges and
ionizations than non-AGN dominated galaxies. We interpret our findings as evidence of differences in the
star-forming molecular gas in AGN host galaxies, and interpret our molecular hydrogen temperature
differences as evidence of AGN host galaxies having a warmer or more dense warm molecular hydrogen
"Running up the Gas Bill: The Price of Leaving Your AGN On"
October,26 2017, at
Harvey Richer (University of British Columbia)
Abstract:The James Webb Space Telescope is a 6.5 meter diameter telescope that is optimized
for infrared wavelengths (~1 to ~30 microns). In the 1-2 micron regime it will reach a
limiting flux density in a time that is about 100 times shorter than Gemini.
The impact of the telescope on all aspects of astronomical research will be
enormous including that related to globular star clusters. In this presentation I will
discuss a few areas where it will be particularly powerful in exploring globular
cluster science including a search for possible ancient planets.
"How the James Webb Space Telescope Will Impact Globular Star Cluster Science"
October,26 2017, at
Chris Mann (University of British Columbia)
Abstract:Stellar mass black holes (a few tens of Msun) resulting from end-stage stellar evolution and supermassive black holes (10^6 - 10^9) found in the cores of most galaxies are well established in the observational literature. What are conspicuously absent are detections of black holes with mass between these two extremes. Intermediate mass black holes (IMBHs) in the range of 10^3 - 10^5 Msun have yet to be conclusively discovered, but their proposed formation mechanisms imply that the dense stellar environments in the cores of globular clusters are a good place to look for them.
Our study searches for the kinematic signature of an IMBH in the core of the globular cluster 47 Tucanae. We utilize ultraviolet HST photometry to produce proper motion data for ~50,000 stars in the cluster core. By comparing the velocity dispersions profile of the cluster to theoretical Jeans-derived models and N-body simulations, we detect the influence of a modestly-sized IMBH. Our current estimate for the IMBH mass is something like 2500 +/- 1000 Msun, though our model is undergoing continuous adjustment.
"A Kinematic Search for an Intermediate Mass Black Hole in 47 Tucanae"
October,12 2017, at
Harvey Richer (University of British Columbia)
Abstract: When I was in graduate school, the most boring aspect
of my education was doing stellar astrometry - the positions and motions
of the stars. This to me sounded like very old fashioned astronomy. All that
has changed in recent years and astrometry has become one of the most
exciting fields in astronomy today. In this presentation IÃ¢ÂÂll talk about some
of our recent results in globular star cluster research that depend sensitively
on accurate astrometry.
"How I learned to love proper motions"
October 11, 2017, at
Abstract:Massive stars strongly influence their immediate surroundings during their lifetimes (via e.g. protostellar jets, strong stellar winds, ionising radiation, supernovae). On larger scales, feedback from massive stars regulates the formation and evolution of entire stellar clusters and dominates the mass and energy cycle in star-forming galaxies like the Milky Way. Qualitatively, the effect of massive stars on their environment is well understood, but a solid quantitative, observational analysis is still missing. The results of recent feedback observations of a variety of structures and environments within massive star-forming regions will be shown, carried out with the integral field spectrographs MUSE and KMOS at the Very Large Telescope. I will discuss the advantages (and caveats) of integral field spectroscopy in tracing and quantifying feedback from massive stars, and describe the bigger picture that connects feedback on small (cloud) scales to that on large (galactic) scales.
"Tracing feedback in massive star-forming regions with integral field spectroscopy"
October 5, 2017, at
Andreea Petric (IfA/CFHT)
Abstract:Observations of the dynamics of stars and gas in the nuclear regions of nearby galaxies suggest that the overwhelming majority of spheroidal galaxies in the local Universe contain massive black-holes (BH) and that, with some important caveats, the masses of those central BH correlate with the velocity dispersion of the stars in the spheroid and the bulge luminosities. Much research has been dedicated to understanding the mechanisms responsible for such a fundamental - perhaps causal - relation. An accurate census of the basic properties of the cold interstellar medium (ISM) in galaxies with accreting super-massive black holes at their centers, i.e. galaxies that host active galactic nuclei (AGN), is pertinent to those investigations because cold molecular gas fuels both black hole growth and star-formation.
We present high sensitivity observations taken with the Herschel Space Observatory to estimate the cold ISM content in a sample of ~200 nearby,optically luminous QSOs. The cold ISM properties of these luminous AGN are discussed in the context of models that envision that quasar activity is triggered by gas-rich galaxy mergers. We also present infrared spectroscopic and photometric observations of a sample of ~200 nearby, Luminous Infrared Galaxies (LIRGs). Luminous Infrared Galaxies (LIRGs) make stars and grow super-massive black holes (SMBH) at a faster rate than most of their local counterparts. Their number density increase with redshift until z~1 when they dominate galaxy evolution. Some are mergers, some are not, some are feeding the central SMBH, others may not be. Because of this, LIRGS constitute a perfect laboratory to observe and study how galaxies grow and to test the conditions in which gas rich mergers trigger episodes of growth for the central SMBH and the host galaxy.
"The Care and Growth of Super Massive Black Holes"
October 4, 2017, at
Laurent Drissen (L'Universite Laval)
Abstract:SITELLE, CFHT's Imaging Fourier transform spectrometer, has been in place for two years now.
In this talk, I will present SITELLE's history, very briefly describe how it works, and highlight some
of its scientific capabilities.
"A brief history of SITELLE"
September 27, 2017, at
Clare Higgs (University of Victoria)
Abstract:The Solo (Solitary Local) Dwarf Galaxy Survey is a volume limited sample of all nearby (< 3 Mpc) and isolated ( > 300 kpc from the Milky Way or M31) dwarfs, with wide-field g and i imaging. This survey uses resolved stellar populations to parameterize these low mass systems. Comparison to the well studied satellite dwarfs characterizes the evolutionary impact of a large galaxy in close proximtity. The deep, wide field nature of this survey also lends itself to searching for substructure around these dwarfs, both globular clusters and possible faint satellites. I present a subset of Solo dwarfs, which lie within the virial radius of the Local Group. This sample has been characterized using consistent methods, despite their diversity in mass and size. The analysis focuses on extended faint stellar structure, stellar populations and morphology. We intend to use this subset to examine trends with star formation history, and separation from a large host. This first subset emphasizes both the unique challenges and advantages of this survey. The Solo Survey provides detailed look at the extended structure of dwarfs and helps to characterize the evolution of galaxies in the faint limit.
"Solo Dwarf Galaxies in the Local Group"
August 30, 2017, at
Simon Petrus (University of Grenoble)
Abstract:Luminous Infrared Galaxies (LIRGs) make stars and grow super-massive black holes (SMBH) at faster rates than most of their local counterparts. Their numbers increase with redshift, until about a redshift of 1.Their numbers increase with redshift, until about a
redshift of 1 when they dominate galaxy evolution. Some are mergers,
some are not, some are feeding central SMBH, others may not. Because
of this, LIRGS constitute a perfect laboratory to observe and study
how galaxies grow. The main fuel for this growth is molecular gas,
and the aim of my internship was to study this gas. Out of a sample
of ~200 LIRGs, 10% appear to have more molecular gas at the center
relative to IR and other coolant emission. We followed seven of
those LIRGs with Gemini's Near-Infrared Spectrograph (GNIRS). I
measured the mass and kinematics of their warm molecular gas and
found that all might have bulk flows, associated with massive
star-formation in the central region. I estimated extinction free
star-formation rates using Hydrogen recombination lines and looked
for evidence of shocked gas as from [Fe II] emission. I will also
talk about my opportunity to do classical observing from the
glorious top of Maunakea, at Subaru's telescope. During this night
Andreea Petric, Jameeka Marshall and I, observed a recent Active
Galactic Nuclei activation to study the impact of this awakening on
the Interstellar Medium of its host galaxy.
"Molecular Gas in Luminous Infrared Galaxies"
August 14, 2017, at
Olivia Lim (University of Montreal)
Abstract:SPIRou is a near-infrared spectropolarimeter and high-precision
velocimeter expected to be installed at CFHT at the end of 2017. It is mostly
dedicated to the search and characterization of exoplanets orbiting low-mass
stars such as M dwarfs. In this context, it is important to not only select
the right candidates to observe but also to better understand how their
activity can affect the observations. In this talk, I will present the two
projects I have been working on this summer. The first part of the
presentation will focus on the project at CFHT, supervised by Pascal FouquÃÂÃÂ¯ÃÂÃÂ¿ÃÂÃÂ½.
This project aims at confirming and ruling out binary and multiple systems
made of at least one M dwarf to avoid observing such systems with SPIRou and
also to determine the occurrence of multiplicity among M dwarfs. I will
present an automated procedure that first, detects possibly false binaries or
multiples, and second, could verify if other systems are bound. The second
part of the presentation will be on the project in Montreal, supervised by
Lison Malo. The goal of this project is to measure the magnetic field in
M dwarfs to better filter out activity signals from spectra that will be used
to search for exoplanets. I will briefly present our latest results along
with comparisons to measurements obtained by different methods.
"Preparing for SPIRou: Binaries and magnetic fields in M dwarfs"
July 24 2017, at
Meg Schwamb (Gemini Observatories)
Abstract: Planet Four and Planet Four: Terrains
are citizen science projects mining Mars
Reconnaissance Orbiter mages to explore how the south pole of Mars is
sculpted by the never-ending cycle of freezing and thawing of exposed
carbon dioxide ice. In the summer, carbon dioxide geysers loft dust and
dirt through cracks in the thawing carbon dioxide ice sheet to the
surface where winds blow the material into the hundreds of thousands of
dark fans observed from orbit. Planet Four enlists over 136,000
volunteers to map the sizes, shapes, and orientations of these fans in
HiRISE images. Planet Four is creating an unprecedented wind map of the
south pole of Mars in order to probe how the Martian climate changes over
time and is impacted year to year by dust storms and and other
global-scale events. Planet Four: Terrains, aims to study the
distribution of the geyser process across the south pole and identify new
targets of interest for HiRISE. Over 12,000 people have helped identify
the channels and pits (dubbed araneiforms) carved during the geyser
formation process. In this talk, I'll give an overview of Planet Four and
Planet Four: Terrains and present the latest results from these projects.
"Exploring Mars with 150,000 Earthlings"
May 2017, at
Calen Henderson (JPL)
The past three years have witnessed a revolution in microlensing searches for exoplanets. Spitzer campaigns in 2014, 2015, and 2016 have transformed space-based microlensing observations from a novelty to an industry. Campaign 9 of Kepler's extended K2 mission conducted the first automated microlensing survey from the ground and from space. These endeavors facilitate measuring a key observable known as the satellite parallax, which leads to model-independent mass measurements for the lensing systems and opens a new window for astrophysical exploration. I will discuss the scientific methodology and utility of these missions, highlight several key results, and emphasize the preparatory work for and expected yields of the WFIRST microlensing survey.
"Space, the Next Frontier: Exoplanetary Microlensing in the era of Spitzer and K2 with an eye toward WFIRST"
January 19 2017, at
Elodie Hebrard (York University)
Abstract: The detection extra-solar planets through radial-velocity searches
is likely limited by the intrinsic magnetic activity of the host stars. The
correlated magnetic noise that arises from their natural radial-velocity
variability (jitter) can easily mimic and hide the orbital signals of
super-Earth and Earth-mass exoplanets.
The modeling of the RV jitter is thus essential to extrasolar planets searches.
I will present here a technique we can use to filter out the RV activity
jitter of low-mass star as well as what we currently know about the magnetic
field of cool stars
"The magnetic personality of stars"
Seminars at other Institutions operating on Mauna Kea and the Big Island:
List of recent past seminars at CFHT.
E-mail correspondence to Andreea Petric: (Petric (at) cfht (dot) hawaii (dot) edu) who coordinates the seminars.