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ASTR1001 Zog: The Second Data Release

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Title: ASTR1001 Zog: The Second Data Release


1
ASTR1001 Zog The Second Data Release
2
Results to date
  • In a recent article in Scientific Zoggian, Prof
    Paul Franciz suggests that the astronomical
    community seems to have reached a consensus on
    some issues.
  • Virtually everyone seems to agree that the
    Greater Milkstain is a collection of around 10
    million stars, clustered in the centre. Our own
    star seems to lie in the outer regions of this
    vast star cluster, which we are calling a
    galaxy.
  • It is also widely (but not universally) accepted
    that at least some fuzzballs are other galaxies
    much like our own.
  • There have been a few attempts to estimate the
    size of the GMS, and distances to other
    fuzzballs, but there is no consensus yet on these
    values.
  • Fuzzballs show both red- and blue shifts. No
    clear pattern has yet emerged, and the blue spots
    remain an enigma.

3
Wagner, Bach and Hayden (IAP)
  • This group have been trying to measure a distance
    to the blue spots. They asked for and were
    awarded time on the Bubble Space Telescope to
    look for parallax in the blue spots. No parallax
    was found the blue spots must therefore be more
    than about fifty light-years away.
  • Many individual stars in the Greater Milk Stain
    were also included in their image of the North
    Blue Spot. These stars also show no measurable
    parallax. They typically have measured fluxes of
    around 10-16 W m-2 nm-1 in the V band.

4
Gilbert and Sullivan
  • This group asked for long exposure images of the
    blue spots with the Bubble Space Telescope. The
    time assignment committee considered their
    request to be sensible, as many astronomers are
    facinated by these mysterious objects, and
    allocated 40 orbits of exposure to each blue spot.

5
  • Up close, both blue spots look quite similar to
    how they appear unmagnified. Neither breaks up
    into stars (at the 0.1 arcsecond resolution of
    the Bubble Space Telescope), though the North
    Blue spot image is full of stars from the Greater
    Milk Stain.
  • One surprise under magnification, the North Blue
    Spot (the one within the Greater Milk Stain) has
    jets of fuzzballs, just like the South Blue Spot.
  • Another new result many new jets of fuzzballs
    were found around both blue spots jets too faint
    and small to have been seen before. These faint
    jets are slightly bluer in colour than the well
    known bright ones.

6
Diaz, Heston and Smythe (Ozford Uni)
  • This team, together with many collaborators, have
    been mapping the whole sky, using a special pair
    of wide field telescopes.
  • Such telescopes are called Schmidt telescopes,
    and use a special combination of lenses, mirrors
    and photographic plates to take photographs of a
    whopping 36 square degrees of the sky in one go.
    Two such telescope, the Palomarz and
    Anglo-Auztralian Schmidts, have been
    photographing the whole sky for ten years. They
    have taken these photographs, digitised them, and
    have used them to construct a complete digital
    map of the sky on 100 cd-roms.

7
  • The Anglo-Auztralian Schmidt

8
  • The first result concerns the jets. With the all
    sky digital map they have been able to show that
    they extend out from the North Blue Spot as well
    as the South one the northern jets have, until
    now, been lost in the midst of the Great Milk
    Stain.
  • Furthermore, the Jets seem to extend further out
    from the blue spots than anyone previously
    expected. As they get further from the spots, the
    gaps between fuzzballs get very large, but they
    can trace some jets out to five degrees from the
    blue spots!

9
  • The fuzzballs that lie in the jets are always
    very faint ones they never see the famous bright
    fuzzballs like M23 or M86 in these chains. The
    jets with bright first members (the fuzzball
    furthest from the blue spot) tend to have a
    bigger gap between the first and second members.
    In the table below theyve measured the
    declinations of the first four members of two
    jets. The first jet has the brighter first member.

10
  • They have counted fuzzballs as a function of
    their brightness. After calibrating their
    photographic map, they came up with a list of
    over a million fuzzballs all the fuzzballs in
    the sky with fluxes greater than 10-19 W m-2
    nm-1, anywhere in the sky.
  • The approximate number of fuzzballs as a function
    of their flux is listed in the table below.

11
  • The number of bright fuzzballs (Flux gt 10-17 W
    m-2 nm-1) per unit area seems to be relatively
    uniform across the sky (though they do seem to be
    concentrations of fuzzballs in a few places).
    Fainter fuzzballs, however, are more common near
    declination 90 and -90. Near declination zero,
    the very faintest fuzzballs are only half as
    common as they are at the celestial poles.

12
Carter and Thoris (Helium Institute)
  • These researchers managed to persuade the Space
    Telescope Science Institute to take a really deep
    exposure of a random part of the sky. A really
    deep exposure takes a lot of Bubble time, so they
    were only given time to image one region of the
    sky. Furthermore, their data was made generally
    available to everyone as soon as it was taken
    publicised as the Bubble Deep Field.
  • 40 orbits of Bubble time were used to image a
    small region of the sky at right ascension 0,
    declination 0, through each of three filters B
    (0.39-0.5 ?m), V(0.45-0.55 ?m) and R (0.55-0.75
    ?m). These were combined to produce a colour
    image of this region.

13
  • The Bubble Deep Field 120 orbits exposure with
    the Wide Field Planetary Camera 2.

14
  • They have counted fuzzballs as a function of
    their brightness. They then extrapolated their
    counts to the whole sky, assuming that the
    average density of fuzzballs in the BDF extends
    over the whole sky. Their field of view is too
    small to measure the space density of brighter
    galaxies, and the error bars on the number of
    galaxies in the first row is large.

15
Verdi and Puccini (Venesia Instiute)
  • Hearing of the recent remarkable discovery of
    jets around the North Blue Spot, this group used
    the William Herzchel Telescope to get spectra of
    the fuzzballs in one of these jets.

16
  • They obtained spectra of four fuzzballs from one
    of the biggest jets extending from the Northern
    Blue Spot, as shown below.

B1
B2
B3
B4
17
  • All four fuzzballs had similar spectra spectra
    resembling those of typical stars.

Relative Flux
Observed Wavelength (nm)
18
  • The only significant differences between the
    spectra were that the lines were shifted. All
    four fuzzballs were blueshifted - the blueshifts
    are listed below.

19
Strittmatter and Shu, Zteward Observatory
  • These two have led a consortium of 73 astronomers
    from fifteen countries in doing a massive X-ray
    and radio survey of the whole sky.
  • The radio observations were made with the
    Auztralia Telescope Compact Array in the south,
    and the Very Large Array in the north. Both
    groups combined to do an X-ray survey of the
    whole sky using the XMM satellite (X-rays do not
    penetrate the atmosphere).

20
  • The Compact Array

21
  • The VLA (Very Large Array)

22
  • The X-ray Multi-Mirror (XMM) satellite.

23
  • The radio maps detected thousands of sources,
    most of them looking something like this. Blue is
    an optical image. Red is the radio map showing
    twin jets extending away from a small faint
    fuzzball.
  • Most sources have radio fluxes of less than half
    a Jansky. The one spectacular exception is
    fuzzball M12, which has a colossal flux of 11
    Janskys.
  • A Jansky is 10-26 W m-2Hz-1.

24
  • Here is an optical image of M12 far and away the
    most powerful radio source in the sky. Looks much
    like a normal fuzzball. It lies at coordinates
    RA 236.88, Dec 37.13.

25
  • In the radio it looks quite different, as can be
    seen in these three images, taken at different
    resolutions. It seems to have a jet of
    relativistic particles squirting out in both
    directions.

26
  • The second most powerful X-ray and radio source
    in the sky was Galaxy NFC64, an optically rather
    boring fuzzball that had been observed with the
    BST by Group 1 in the first round of
    observations. XMM detected 27 X-rays per second
    from it.
  • It was also a double radio source, though the two
    jets were of more similar brightness than those
    of M12.

27
  • The two blue spots were not strong X-ray or radio
    sources.
  • However, all the fuzzballs in one jet sticking
    out of the Southern Blue Spot were strong X-ray
    and radio sources.
  • The same applies to the Northern blue spot all
    the fuzzballs in one jet sticking out of it were
    strong X-ray and radio sources.

28
The Radio and X-ray Jet
  • The other jets radiating from the blue spots did
    not emit strong radio or X-ray flux. No new jets
    were discovered, travelling in any direction.
    Published images were checked, and this jet seems
    similar to all the others optically. In the
    radio, all sources in both chains are double
    radio sources, similar to M12 and NFC64. All the
    radio axes point in the same way (roughly
    perpendicular to the direction of the jets).

Details of the Southern Radio/X-ray Jet
29
  • Here are the details of the Northern Jet. As with
    the Southern Jet, the brightest source, which in
    both cases is the furthest from the Blue Spot, is
    called A, and the others are numbered in order
    as they approach the blue spots. There are many
    more members of both jets - only those from which
    more than 0.5 X-rays per second are detected are
    listed.

Details of the Northern Radio/X-ray Jet
30
De Canis et al.
  • This group have been slowly and painstakingly
    searching for variable stars in the central
    regions of the Greater Milk Stain.
  • This is very difficult work as these stars are
    faint - the power of the Very Large Telescope
    (VLT), with its four 8m mirrors was required.
  • Stars pulsing with 2 hour periods were found.
  • They further seached for such pulsing stars in
    two of the brightest fuzzballs in the sky M23
    and M86. This observation required the Bubble
    Space Telescope. Once again, they were successful
    in finding stars with 2 hour pulsation periods.

31
  • The Very Large Telescope

32
  • Here is a table of the average peak brightness of
    the 2-hour pulsing stars in the three targets.
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