The slides in this collection are all related and should be useful in preparing a presentation on SIM PlanetQuest. Note, however, that there is some redundancy in the collection to allow users to choose slides best suited to their needs. - PowerPoint PPT Presentation

Loading...

PPT – The slides in this collection are all related and should be useful in preparing a presentation on SIM PlanetQuest. Note, however, that there is some redundancy in the collection to allow users to choose slides best suited to their needs. PowerPoint presentation | free to download - id: 1b7b0e-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

The slides in this collection are all related and should be useful in preparing a presentation on SIM PlanetQuest. Note, however, that there is some redundancy in the collection to allow users to choose slides best suited to their needs.

Description:

By observing samples of stars throughput the Galaxy. By sampling different star populations ... understanding discrepancies between CDM theory and observations ... – PowerPoint PPT presentation

Number of Views:15
Avg rating:3.0/5.0
Slides: 34
Provided by: davidh95
Learn more at: http://relativitycalculator.com
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: The slides in this collection are all related and should be useful in preparing a presentation on SIM PlanetQuest. Note, however, that there is some redundancy in the collection to allow users to choose slides best suited to their needs.


1
The slides in this collection are all related and
should be useful in preparing a presentation on
SIM PlanetQuest. Note, however, that there is
some redundancy in the collection to allow users
to choose slides best suited to their needs.
2
Taking the Measure of the Milky Way
  • SIM will probe the structure of our Galaxy
  • Fundamental measurements of
  • Total mass of the Galaxy
  • Distribution of mass in the Galaxy
  • Rotation of the Galactic disk
  • How?
  • By observing samples of stars throughput the
    Galaxy
  • By sampling different star populations

3
Calibrating the Cosmic Distance Scale
  • Current parallax measurements reach only to about
    100 pc.
  • Distances are derived from a staggered set of
    rungs, each relying on the previous step.
  • SIM will calibrate the rungs of the distance
    ladder throughout the Galaxy (10 to 25,000 pc)

4
Dynamics of Galaxy Groups within 5 Mpc
  • Simulation
  • Simulated 3-D motions projected onto a plane
  • Smeared tracks show the simulated motions of
    galaxies
  • Circles show current positions
  • SIM will test this model
  • SIM will measure current 2-D velocities across
    the sky

Simulated time-lapse photo of 30 galaxies
closest to our Milky Way (1-billion year exposure)
5
NGC 6822
6
Holmberg II
7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
Milky Way Studies
  • Key issues
  • Mass potential of MW from 3-D motions of tidal
    tails
  • Total mass from distant halo objects
  • Legacy orbit determinations for MW satellites
  • Legacy orbit determinations for all Galactic
    globulars
  • Surface density of disk (non-local Oort limit)
  • Dynamics of the bulge and the Galactic bar
  • Science Drivers
  • Tidal Tails
  • Globular Clusters, Satellites, Open Clusters
  • Galactic Disk
  • Central Galaxy
  • Fundamental Parameters

11
Mass Potential Halo Objects
  • Proper motions orbit shapes
    gravitational potential
  • Get radial dependence, q, triaxiality
  • With only RVs, have to make assumptions
    about, e.g., radial vs. isotropic orbits.
  • Orbit of Leo I (at 270 kpc) -- currently 4X MW
    mass difference if bound vs. unbound.
  • Total MW mass comes from most distant (gt90 kpc)
    objects

12
Mass Potential Tidal Tails
  • RVs of tidal tails alone cannot yet distinguish
    between various potentials with flat rotation
    curve at large RGC (e.g., NFW vs. log)
  • Current problem of leading arm Sgr RVs vs. model
  • Any evidence of dynamical friction independent
    satellite mass estimate (see poster 142.02)
  • Any evidence of deviations encounters
    w/lumps
  • Need SIM for 10-15 mas/yr accuracy to V18-20

13
Star Clusters
  • Measure Proper Motion of every Galactic globular
    cluster and 100 open clusters a legacy for
    the astronomical community
  • With SIM PMs, we can search for correlations
    between orbits and streams.
  • Are all halo GCs found in streams?
  • Implications for Galaxy formation
  • Cluster dynamics/evolution tied to orbits
  • Bulge/disk globulars useful probe of central
    potential (least well known part of potential)
  • Need SIM for 10 mas/yr accuracy to V18-20

14
Dwarf Satellites
  • Measure Proper Motion of every Galactic satellite
    galaxy
  • Orbits crucial to understanding formation and
    evolution of these most common and least
    understood types of galaxy
  • Crucial for understanding discrepancies between
    CDM theory and observations
  • Need SIM for 10 mas/yr accuracy to V20

15
Galactic Disk
  • Determination of Galactic Rotation Curve
  • Difficult to do with Radial Velocities alone
    (have to assume circularity and have distances
    well known).
  • Influence of bar not yet established.
  • Can place MW on Tully-Fisher relation.
  • Need SIM for 10-15 mas/yr proper motion to V16.

16
Galactic Disk/Bulge
  • Determine relative amounts of dark and luminous
    matter inside the solar circle
  • At large radii we have some knowledge from
    external galaxies (satellites, weak lensing)
  • At small radii (lt5 kpc) Dark Matter fraction is
    uncertain (5? or 50?) (maximum disk problem)
  • Theoretical predictions (strong Dark Matter
    cusps) vs. large Dark Matter cores observed in
    external galaxies.
  • Measuring Oort limit at other radii and bulge
    motions have the potential to answer these
    questions
  • Need SIM for 10-15 mas/yr motions to V16

17
Galactic Center
  • Measure distance to Galactic Center
  • Distance to Sgr A from orbit of S2 (Eisenhauer
    et al. 2003)
  • Accurate to 5
  • 1-3 by 2010
  • VLT and Keck
  • 3 error in Ro, QLSR
  • 5 error in Mass

18
Galactic Center
  • SIM HST Measurements to better than 1
  • Ro and QLSR are of fundamental importance should
    not rely on SgrA distances only.
  • Chance to confirm that the central black hole is
    indeed located at the Galactic Center for the MW.
  • SIM can sample a different and larger population
    of stars (bulge and bar) 100-500pc from Galactic
    Center. Probe potential over poorly studied
    distance range.
  • Test of parallax vs. dynamical center (distance
    at which bulge stars change direction of
    motion)
  • Need SIM for 6 mas parallaxes to V16

19
Conclusions
  • Taking Measure of the Milky Way Key Project will
    provide unique insight into the following key
    issues
  • Mass potential of Galaxy from 3-D motions of
    tidal tails
  • Total mass from distant halo objects
  • Legacy orbit determinations for all MW satellite
    galaxies
  • Legacy orbits for all Galactic globulars/numerous
    open clusters
  • Surface density of disk (non-local Oort limit)
  • Dynamics of the bulge and the Galactic bar
  • We will also independently
  • Refine the distance measurement to the Galactic
    Center.
  • Refine measurement of the Galactic rotation curve.

20
Galactic Dynamics Dark Halo of Our Galaxy
  • Study the classical problems of size, mass
    distribution, and dynamics of the Galaxy, using
    stellar velocities
  • Example Debris tail orbits (Sagittarius dwarf
    spheroidal galaxy orbits Milky Way)
  • Gravitational forces pull out tidal tails of
    stars
  • The orbits of these tails trace the past history
    of the dwarf
  • They also trace the mass distribution of the
    Milky Way
  • Distances to 5 at 10 kpc, for stars with V lt 20
  • Proper motions to 0.1 km/s at 10 kpc
  • Combine with ground-based radial velocities

Tidal tail simulation Dwarf galaxy in orbit
around the Milky Way
21
  • Discovery of multiple tidal tail targets
  • (Sgr, Pal 5, Monoceros/Argus, TriAnd)

22
  • Much new info on Sgr system
  • Initial 2MASS work reveals gt360o arms
  • RV constraints
  • With only 4-D constraints, problems/contradiction
    s remain
  • Modeling of Sgr and Galactic halo
  • Leading Arm RVs wrong
  • Prolate vs. Oblate ambiguity

23
  • Much new info on Sgr system (cont.)
  • New discovery -- two more wraps of Sgr debris.
  • Evidence that Sgr orbit evolved from large
    circular to smaller elliptical orbit about 2 Gyr
    ago due to collision with LMC.
  • Proper motions of faint stars needed to
    understand this complicated interaction
    independent confirmation of LMC m and halo
    potential

24
  • Discovery that halo is almost completely
    dominated by tidal streams
  • Obtaining halo properties from Jeans equation
    applied to random halo stars more difficult.

25
Quasar Astrophysics Using Astrometry
  • Quasars are the most powerful objects in the
    universe
  • Many quasars emit twin jets of relativistic
    plasma
  • Optical observations average the entire region
  • Accretion disk, hot corona, jets
  • Jets have been studied by VLBI (radio) at 100
    µas scales
  • SIM will measure
  • position shifts due to variability
  • color-dependent relative positions of the
    emission
  • These measurements will open up a research area
    only studied with VLBI

SIM can determine if the visible light from
quasars originates in hot gas around an accretion
disk or from a relativistic plasma jet
SIM can detect the orbital motions of two merging
black holes in the centers of massive galaxies
26
Quasar Astrophysics Using Astrometry
  • Quasars are the most powerful objects in the
    universe -
  • Many quasars emit twin jets of relativistic
    plasma
  • Ground-based optical observations average the
    entire region
  • Accretion disk, hot corona, jets
  • SIM will measure
  • position shifts due to variability (relative
    brightening or motion)
  • color-dependent relative positions of the
    emission
  • SIM will enable studies much closer to the
    central supermassive black hole than VLBI or
    ground based optical interferometry can reach

27
Understanding the Fundamental AGN Power Source
  • Accretion onto massive black holes fuels the
    energetic AGN phenomena-- but how does it work?
    Not just intrinsically interesting, but AGN
    directly affect the development of other
    structures in the universe (galaxies,
    clusters, 10-Mpc bubbles)
  • AGN and starbursts reionized the universe,
    forming bubbles around massive galaxies by z 6,
    as shown in series of papers beginning with
    observations of Sloan high-z quasars

200,000 ly structure generated by jets in M87
28
The Most Basic Physics
The Core
  • What are the sizes and geometric relations
    between the components of the core region
    jets, accretion disk, hot corona ?
  • Which components dominate the optical emission?
  • The structures we measure with SIM are either
    optical synchrotron emitters from particle
    populations distinct from the radio-synchrotron
    emitters, or thermal emitters from the hot corona
    or accretion disk.

29
Estimating the Emission Region Size
Since we wrote our SIM proposal in 2000, Seyfert
nuclei of NGC 4151 and NGC 1068 were detected by
Keck Interferometer and VLTI, respectively,
(Swain et al. 2003, ESO 2003).
  • Accretion disks are small
  • 160 µas (at 15 Mpc - M87)
  • 2 µas (at 3C345 - z 0.6)
  • Hot corona region is also small
  • 70 Rs corresponds to 1 µas at z 0.6
  • Jet shocks are small- a shock in the jet of M87
    outshone the nucleus! 4-wk variability size scale
    corresponds to 30 ?as (Perlman et al. 2003 ApJ
    Letters)
  • These sizes are well beyond the reach of ground
    based optical interferometers (e.g., Keck
    Interferometer and VLTI) - to study their
    motions, we need SIM.

30
Astrometric Signature of a Black Hole Binary
  • Binary black holes may be ubiquitous in galactic
    centers, rather than rare, because mergers may
    stall out. Orbital motion of binary black holes
    is detectable with SIM, using astrometric reflex
    motion of their photocenter, just like we detect
    planets around stars.

31
AGN Science With SIM- More Compelling than Ever
  • AGN dust tori in nearby Seyferts are now being
    studied by the Keck Interferometer and VLTI, but
    only SIM can measure motions at the light-week
    physical scale
  • Discovery of the bulge mass- central black hole
    mass relationship triggered an avalanche of
    papers on accretion rates, quasar lifetimes, and
    the detection of fossil black holes. SIM can
    observe structures in low and high power AGN,
    addressing physics of a variety of central black
    hole masses and accretion rates.
  • Binary black holes may be ubiquitous rather than
    rare because mergers may stall out before the
    black holes coalesce (cf. NSF Grand Challenge).
    SIM can measure orbital motion directly by
    tracking motion of the photocenter.

32
Sample Permatile for relative astrometry
  • Select tile centers for objects of interest
  • Monitor optical brightness of candidates for next
    n years
  • Formulate SIM observing strategy

33
Optical Brightness Monitoring
  • Quasars in the range of V 15-17, but a few are
    brighter, such as 3C273
  • Historically, the most compact quasars are the
    most variable, so we need to ensure the ones we
    observe with SIM are consistently the brightest.

We have begun a monitoring program on the Palomar
60 telescope. Discussions with European (and
other) monitoring groups have begun
(international conf. in April 2005) Strong,
non-coincidental agreement on source lists with
GLAST mission (launch 2007) - brightest, most
compact blazars are the ones they are most likely
to detect
About PowerShow.com