ASTR1001 Zog: The Second Data Release

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ASTR1001 Zog The Second Data Release
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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.

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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.

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• 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.

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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.

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• The Anglo-Auztralian Schmidt

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• 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!

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• 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.

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• 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.

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• 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.

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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.

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

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• 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.

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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.

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• 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
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• All four fuzzballs had similar spectra spectra
  resembling those of typical stars.

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

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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).

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• The Compact Array

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• The VLA (Very Large Array)

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

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• 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.

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• 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.

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• 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.

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• 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.

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• 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.

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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
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• 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
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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.

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• The Very Large Telescope

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

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Smoot and Hawkins

• These reseaarchers built a satellite to measure
  the microwave background radiation.
• Using ground-based microwave telescopes, it was
  quickly established that a microwave background
  does indeed exist.
• Their Cosmic Background Explorer satellite was
  launched to measure this background precisely.
• The microwave background was rapidly discovered
  to vary in brightness across the sky. It is about
  10 brighter in the direction of both blue spots
  than it is at Declination zero.

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• Here is an all-sky map of the microwave
  background. Declination zero is along the middle.
  Declination 90 is at the top and -90 is at the
  bottom. The intensity at declination 90 or -90
  is 10 greater than that at Declination 0.

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• When this simple correlation with declination is
  removed from the data, some residual lumps are
  seen. These residual brightness patterns have an
  amplitude of about 0.001 (ie. the brightest bits
  are 0.001 brighter than the faintest bits).
• Remarkably, the pattern of bright and dark
  regions looking towards Declination 90 and -90
  are the same! The same structures are seen!
• The structures do not seem to correlate with
  fuzzballs or the milkstains.

0 RA
0 RA
90 RA
90 RA
90 Dec North
-90 Dec South
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Fidelis and Semper

• This group requested BST spectra of the objects
  found in the Bubble Deep Field, in particular the
  blue galaxy-like objects, the small red objects,
  and the objects that look like fuzzy balls.
• The time allocation committee rejected this
  proposal given that it took 120 orbits to even
  get an image of these things, obtaining spectra
  would require about 10,000 orbits - four years of
  exclusive BST time. The committee were not
  convinced that useful science would come out of
  this colossal investment of time.
• The group did, however, persuade some
  collaborators with access to the Keck Telescope,
  Zogs biggest ground-based telescope, to get
  spectra of a few of the brightest sources in the
  Bubble Deep Field. The small red objects were far
  too faint to obtain spectra, but a few ratty
  spectra were obtained of the brightest blue
  elongated things and the grey fuzzy balls.

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

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• The Keck Telescope

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• The blue, elongated things had featureless, blue
  spectra. No emission or absorption-lines were
  seen, but the signal-to-noise ratio of the
  spectra was so poor that this wasnt really a
  surprise (these are very difficult things to get
  spectra of).

Relative Flux
300nm
700nm
Observed Wavelength (nm)
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• The faint fuzzy things had rather different
  spectra, though still pretty ratty. Here is a
  typical one.

Relative Flux
600
900
300
Observed Wavelength (nm)
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Walrus et al.

• Walrus et al are experimental physicists. Hearing
  all the talk about strange geometries, they
  requested money to build an instrument to measure
  p.
• Two instruments were built one to measure it in
  the lab, and one to measure it on much larger
  scales in space (by bouncing lasers between
  spacecraft).
• The ground-based experiment reported that p had
  its normal, expected value with a precision of 15
  decimal places.
• The space-based experiment measured p on a scale
  of 1012m, and once again found that it has its
  normal expected value, to an accuracy this time
  of 10 decimal places.

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Gabriel, Nunn and Weekes (ANU)

• Gabriel et al. requested an X-ray measurement of
  the famous radio source M12.
• The observations were made, and a very strong
  emission was detected 149 X-rays per second.

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The European Zpace Agency (EZA)

• EZA have long been concerned that not enough is
  known about nearby stars. The fundamental problem
  has always been measuring the distances to stars
  unless you know the distance, everything else is
  very hard to determine. They recently launched
  the Hipparchoz satellite, designed to measure
  parallax with unprecedented precision to all
  stars within about 30 pc.
• When its two year mission was completed, it took
  the team scientists another two years to process
  the vast amounts of data.

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Hipparchoz
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Parallax Measurements

• Despite the enormous increase in precision, no
  parallax was measured for either blue spot.
  Likewise, no fuzzball showed parallax, and none
  of the stars in the GMS showed measurable
  parallax.
• Over 7,000 nearby stars did, however, show
  parallax. Of particular interest were 4 pulsing
  stars with two hour periods. These stars were
  chosen because their spectra were very similar to
  the two-hour pulsing stars seen in the GMS and in
  other fuzzballs.
• Parallaxes are measured in arcseconds (and
  arcsecond is 1/60 arcminutes. An arc-minute is
  1/60 degrees). They represent the change in
  apparent position over half a Zog year (ie. The
  coordinates of the star change by this angle
  between two observations six months apart).

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Variable Star Data
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Radar Measurements

• Radar pulses sent to Zogs sun take 18 minutes
  53.33 seconds to make the round trip to the sun
  and back.
• The speed of light, as measured in Zoggian
  laboratories, is the same as it is on Earth.