Bielby

1
Bielby Shanks 2007 MNRAS submitted
Chanda sample of 38 z0.3 clusters
ROSAT sample of 30 low z clusters
2
Interstellar Neutral Hydrogen Emission Structure
and Radio Frequency Continuum Radiation (WMAP)
Signals

• Gerrit L. VerschuurPhysics DepartmentUniversity
  of Memphis

3
Hydrogen line (HI) data side-lobe corrected

• H-line is a spectral signature at 1,420 MHz or
  21-cm wavelength of hydrogen gas between the
  stars
• Used the Leiden-Dwingeloo All Sky Survey
• Hartmann Burton (1997)
• Sidelobe corrected
• Plus some from LAB Survey - Kalberla et al.
  (2005)
• All data will be displayed in galactic
  coordinates - longitude (l) latitude (b)

4
Low velocity
I used 25 HI maps like this to explore the
relationship between HI and WMAP structure in
this area of sky
5
(No Transcript)
6
WMAP ve contours 0.08 0.22 _at_ 0.02 mK
7
Overlay WMAP ve contours on HI inverted
gray-scale map
HI -130 to -120 km/s
In general, anomalous vel. HI are in the
proximity of WMAP peaks.
8
Peak at -126 km/s
Peak at -116 km/s
Inverted grayscale - HI
Contours WMAP peaks
9
A possible model -1
Intercloud plasma
Depending on how the line-of-sight intersects the
colliding HI features, we may expect to observe
alignment of WMAP peaks and HI peaks, or offset
peaks
10
V - 118 km/s
v - 87 km/s
11
Calculate expected number of associations

• Probability that a given WMAP peak will lie
  within a distance r of an HI peak located in an
  area A is
• ?r2 A-1
• But we have many WMAP peaks and very many HI
  peaks at different velocities

12
Calculate expected number of associations

• Nwpeaks 33 consider the 33 brightest
• Nhpeaks 550/3 183 visible over 3 maps on
  average
• N number of cases where direct association is
  expected in this area, A (4,800 square degrees)
• N ?r2 A-1 NWpeaks NHpeaks.

13
Not chance coincidence
14
What did this show?

• For the 1st time, high velocity and intermediate
  velocity HI structures have been found to be
  directly associated
• They both appear to be associated with a lack of
  low-velocity HI
• All three are associated with enhanced continuum
  emission

15
(No Transcript)
16
HVC MI neutral hydrogen data
17
WMAP ve contours
HI - inverted gray-scale
Ha
18
A possible model -1
Intercloud plasma
Depending on how the line-of-sight intersects the
colliding HI features, we may expect to observe
alignment of WMAP peaks and HI peaks, or offset
peaks
19
HVC MI
HI contours
Excess soft X-ray emission Herbstmeier et al.
This lead to a prediction in November, 2006 HVC
MII will be associated with continuum emission
20
Testing a prediction HVC MII would show
something similar to HVC MI
21
Using WMAP ILC data obtained in December, 2006
22
Ha excess
Soft X-ray excesses
At the location of the WMAP peaks, the HI
profiles are double peaked
23
Overlay WMAP ve contours on HI inverted
gray-scale map
HI -130 to -120 km/s
In general, anomalous vel. HI are in the
proximity of WMAP peaks.
24
(No Transcript)
25
Overview

• Since December I have used WMAP data kindly
  provided by Gary Hinshaw and Wayne Landsman and
  compared those data with over 500 HI maps at 2
  km/s intervals for small regions of sky.
• The pattern that has emerged is that when the
  WMAP peak is clearly associated with HI more than
  one HI feature is involved
• Collisions?

26
Conclusions general

• Welcome Back to the Galaxy!
• WMAP small-scale structure may have a significant
  contribution from foreground features associated
  with HI structure
• It is possible that all the small-scale WMAP
  continuum emission structure has a Galactic
  origin
• By examining HI structure in the direction of
  WMAP continuum emission peaks at intermediate and
  high galactic latitudes the study of galactic HI
  is suddenly made very interesting

27
Suggestions for the future

• Convert young cosmologists to the study of
  interstellar structure
• . . . . before they get lost in the cosmos
• Extend study to other areas of the sky - a vast
  opportunity for new discovery
• It is likely that plasma phenomena are key to
  understanding interstellar structure
• Invite plasma physicists to meet with
  astrophysicists studying interstellar structure
  to create common ground

28
Reports

• Further Evidence for the Critical Ionization
  Velocity Signature in Interstellar Neutral
  Hydrogen Emission Profiles
• IEEE Transaction on Plasma Science - August 2007
• This paper offers an explanation for the
  mechanism for producing weak continuum emission
  at the interface between colliding HI features
• High Galactic Latitude Interstellar Neutral
  Hydrogen Structure and Associated High Frequency
  Continuum Emission
• Being reviewed for Astrophysical Journal

29
Acknowledgments

• Dap Hartmann Butler Burton for providing the
  LDS All-Sky Survey data last century
• Wayne Landsman of the WMAP group for providing
  WMAP ILC data for the Target Area in a form I
  could use (uniform l-b grid)
• Butler Burton for his encouragement and valuable
  discussions
• Joan Schmelz for her encouragement, valuable
  discussions, critical readings of my MSs,
  comments on PPTs, and understanding of the key
  issues
• Tom Dame for his holy grail program using a
  data cube that allowed me to make HI maps with
  ease
• Richard Lieu and Jonathan Mittaz for helpful
  discussions

30
v- -8 to 2 km/s
Hole in local HI at the location of the HI peaks
at high and intermediate velocities This has
never before been observed All are associated
with the WMAP peak