-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathexotic_physics.html
213 lines (195 loc) · 15.4 KB
/
exotic_physics.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1" />
<meta name="description" content="The site is intended as a free educational resource about the frontiers of galaxy formation." />
<meta name="keywords" content="early universe, cosmic dawn, first galaxies, first stars, population 3, cosmology" />
<meta name="author" content="Erika Hoffman" />
<title>Exotic Physics - Cosmic Dark to Dawn</title>
<link rel="stylesheet" type="text/css" href="style.css" />
<link rel="icon" href="images/galaxy_icon_d.png">
</head>
<body>
<div class="grid_1">
<! TOP NAVIGATION !>
<header>
<nav class="navbar" style="grid-row:1;">
<a href="index.html"><h1 class="main-header">Cosmic Dark to Cosmic Dawn</h1></a>
</nav>
<nav class="navbar" style="grid-row:1;">
<ul style="padding-top: 27px; ">
<li class="current"><a href="dark_ages.html">What happened during the <span class="bold">Dark Ages?</span></a></li>
<li><a href="cosmic_dawn_1.html">How did the <span class="bold">first stars</span> form?</a></li>
<li><a href="cosmic_dawn_2.html">How did the <span class="bold">first galaxies</span> form?</a></li>
<li><a href="observations.html">How do we <span class="bold">observe</span> them?</a></li>
</ul>
</nav>
<div class="glos">
<ul>
<li>
<! THE DROPDOWN MENU !>
<div class="dropdown">
<button class="dropbtn">
Menu
</button>
<div class="dropdown-content">
<a href="index.html">Home</a>
<a href="dark_ages.html" class="dark_head">The Dark Ages</a>
<a href="big_bang_cmb.html" class="dark_cont">The Big Bang</a>
<a href="cosmic_web.html" class="dark_cont">The Cosmic Web</a>
<a href="exotic_physics.html" class="dark_cont">Exotic Physics</a>
<a href="cosmic_dawn_1.html" class="cd_1_head">Era of the First Stars</a>
<a href="first_stars.html" class="cd_1_cont">The First Stars</a>
<a href="first_black_holes.html" class="cd_1_cont">The First Black Holes</a>
<a href="light_fills_the_universe.html" class="cd_1_cont">Light Fills the Universe</a>
<a href="spin_flip.html" class="cd_1_cont">The Spin-Flip Backgound</a>
<a href="cosmic_dawn_2.html" class="cd_2_head">Era of First Galaxies</a>
<a href="first_galaxies.html" class="cd_2_cont">The First Galaxies</a>
<a href="larger_galaxies.html" class="cd_2_cont">Larger and Larger Galaxies</a>
<a href="epoch_of_reionization.html" class="cd_2_cont">Epoch of Reionization</a>
<a href="later_universe.html" class="later_head">The Later Universe</a>
<a href="cosmic_noon.html" class="later_cont">Galaxies at Cosmic Noon</a>
<a href="our_galaxy.html" class="later_cont">Our Galaxy: The Milky Way</a>
<a href="observations.html" class="obs_head">Obervations Overview</a>
<a href="radio_telescopes.html" class="obs_cont">Radio Telescopes</a>
<a href="lunar_telescopes.html" class="obs_cont">Lunar Radio Telescopes</a>
<a href="space_telescopes.html" class="obs_cont">Space Telescopes</a>
<a href="infrared_telescopes.html" class="obs_cont">Ground-Based Near-Infrared Telescopes</a>
<a href="other_telescopes.html" class="obs_cont">Other Telescopes</a>
</div>
</div>
</li>
<li>
<div class="dropdown">
<button class="dropbtn">Research</button>
<div class="dropdown-content">
<a href="research.html">Research Overview</a>
<a href="group_members.html">Group Members</a>
<a href="collaborations.html">Collaborations</a>
<a href="codes_and_tools.html">Codes and Tools</a>
</div>
</div>
</li>
<li><a href="glossary.html" class="dropbtn">Glossary</a></li>
</ul>
</div>
</header>
<! MAIN IMAGE AND TEXT !>
<div class="page_title">EXOTIC PHYSICS<span style="font-size:4.5vw; line-height:0em;"><br />DURING THE DARK AGES</span></div>
<div class="page_summary">
<div class="box">
During the Dark Ages, the Universe was – at least in the standard picture – a very simple place. The expanding Universe made the hydrogen gas cool off, and gravity began to create structure in both the dark matter and gas. This simplicity means that cosmologists can predict, with great accuracy, what the Universe should look like. But of course the Universe is not always as simple as we expect! The simplicity of the Dark Ages makes it an excellent target for efforts to discover exotic and unknown physics, as any deviations from our expectations would signal brand new physics phenomena. For example, what if dark matter isn’t truly dark? What if it interacts with the hydrogen gas, albeit extremely weakly? What if primordial black holes are sprinkled throughout the Universe? Such phenomena are extraordinarily difficult to separate from the effects of stars and galaxies, but during the Dark Ages they could stand out clearly.
</div>
</div>
<div class="img_cred">
A snapshot of a cosmic string network during the transition from the radiation epoch to the matter epoch.
<br />
Image Credit: <a href="http://www.ctc.cam.ac.uk/outreach/origins/cosmic_structures_four.php" target="_blank" rel="noopener noreferrer">B. Allen & E.P. Shellard cosmic string simulations</a>
</div>
<section class="page" style="background-image: url(images/cosmic_string.jpg); filter: brightness(40%); background-size: cover;">
<div class="scale">
</div>
</section>
<! PAGE BEFORE / PAGE AFTER NAVIGATION >
<section class="page_nav">
<a href="cosmic_web.html">Previous: Spinning the Cosmic Web </a>
<a href="cosmic_dawn_1.html" style="float: right;">Next: Era of the First Stars </a>
</section>
<! MAIN TEXT !>
<article class="main-col">
<div class="in_text_image_left_1" style="background-image:url('images/cosmic_web_unaltered.jpg');"></div>
<div class="text_right_1" style="">
<h1>Why do the Dark Ages provide a powerful testbed for searches for exotic physics?</h1>
<p>
The Dark Ages refer to the period after the cosmic microwave background last scattered (400,000 years after Big Bang) and before the first generations of stars formed (about 50 million years after the Big Bang). During this time, the Universe was an extremely simple place - a nearly uniform sea of neutral hydrogen, unaffected by the photons streaming through it. The gas cooled slowly as the Universe expanded, and gravity began to form the cosmic web. But cosmologists can predict the results of these processes with extreme precision. If we can measure the properties of the gas during the Dark Ages, any deviations from these predictions would provide strong evidence for new physics that is not so simple!
</p>
<p class="img_cred_body">
Image: A visualization of the cosmic web. Each bright knot is an entire galaxy, while the purple filaments show where material exists between the galaxies.
<br />Credit: <a href="https://svs.gsfc.nasa.gov/10118" target="_blank" rel="noopener noreferrer">NASA/NCSA, UIUC, Frank Summers, STScl, Martin White, Lars Hernquist, Harvard</a>
</p>
</div>
<div class="in_text_image_right_3" style="background-image:url(images/annihilation_diagram.png); background-size: contain;"></div>
<div class="text_left_3" style="">
<h1>How might dark matter affect the Dark Ages?</h1>
<p>
We call the missing matter in the Universe "dark" because it does not produce light. Nor does standard dark matter interact with ordinary matter, except in extremely rare events. However, even in the standard picture dark matter is not entirely dark: dark matter particles that collide with each other may annihilate, for example, producing very high-energy radiation called gamma rays. Today, even if such annihilations occur, the resulting gamma rays are typically swamped by the many other gamma-ray sources in the Universe. But during the Dark Ages, where no other light is produced, even an extremely faint glow from annihilating dark matter would be enough to change the temperature of the hydrogen gas. Alternatively, if even a small fraction of the dark matter has a tiny electric charge, those particles will collide with electrons, allowing the dark and normal matter to exchange their energy. These are just examples - cosmologists have identified several mechanisms that would allow dark matter to affect the properties of the cosmic gas during the Dark Ages. If we can measure precisely the properties of that gas, we can study the mysterious properties of dark matter.
</p>
<p class="img_cred_body">
Image: Caption: A diagram of particle annihilation: counterpart particles approach each other, collide, and annihilate into two photons (wavy lines, traveling perpendicularly). Dark matter may annihilate in a similar fashion.
<br />Credit: E. Hoffman
</p>
</div>
<div class="in_text_image_left_5" style="background-image:url(images/cosmic_string.jpg);"></div>
<div class="text_right_5" style="">
<h1>What other exotic processes can affect the Dark Ages?</h1>
<p>
While dark matter models provide one exciting set of mechanisms that would change the standard picture of the Dark Ages, cosmologists have suggested several others too. For example, in some scenarios, small primordial black holes can form very early in the Universe’s history. Under certain circumstances, these objects can heat the surrounding media, or they can produce radio waves. Even more exotic objects called cosmic strings – vast filament-like structures of very high densities – can have similar effects. While strange processes like these cannot be common in the Universe, the simplicity of the Dark Ages will make even rare anomalies stand out easily.
</p>
<p class="img_cred_body">
Image: Snapshot of a cosmic string network during the transition from the radiation epoch to the matter epoch.
<br />Credit: <a href="http://www.ctc.cam.ac.uk/outreach/origins/cosmic_structures_four.php" target="_blank" rel="noopener noreferrer">B. Allen & E.P. Shellard cosmic string simulations</a>
</p>
</div>
<! NO FORTH QUESTION>
</article>
<! OBSERVATIONS AND VOCAB RIGHT SIDEBAR !>
<aside class="sidebar">
<div class="blurb">
<h1>Which telescopes are trying to observe this?</h1>
<div class="telescope_button">
<div class="telescope_img">
<img src="images/dapper.jpg" style="width:140%;">
<div class="tiny_text">Dark Ages Polarimetry Pathfinder (DAPPER)</div>
</div>
<div class="telescope_title"><h3 style="margin-top:0;"><a href="lunar_telescopes.html">Lunar Telescopes</a></h3></div>
</div>
<p>Because there are no luminous sources during the Dark Ages, the only way to observe this era is through the very weak spin-flip background generated by neutral hydrogen, and that signal is extremely difficult to observe from Earth. Low-frequency radio telescopes near or on the Moon are the only instruments currently planning to observe this era.</p>
</div>
<! VOCAB !>
<div class="vocab">
<h2><a href="glossary.html">Vocab</a></h2>
<ul>
<li>Dark Ages </li>
<li>Dark Matter </li>
<li>Primordial black holes </li>
<li>Annihilate </li>
<li>Gamma Rays </li>
<li>Electric Charge </li>
<li>Cosmic strings </li>
<li>Radio Waves </li>
</ul>
</div>
</aside>
<! PAGE BEFORE / PAGE AFTER NAVIGATION >
<section class="page_nav">
<a href="cosmic_web.html">Previous: Spinning the Cosmic Web </a>
<a href="cosmic_dawn_1.html" style="float: right;">Next: Era of the First Stars </a>
</section>
</div>
<div class="grid_2">
<! EXTERNAL LINKS SECTION !>
<section class="links">
<h1>Want to learn more?</h1>
<ul>
<li><a href="https://www.quantamagazine.org/whisper-from-the-first-stars-sets-off-loud-dark-matter-debate-20180329/" target="_blank" rel="noopener noreferrer">This article</a> talks about how a recent observation triggered many questions about exotic physics during the Dark Ages.</li>
<li><a href="http://www.ctc.cam.ac.uk/outreach/origins/cosmic_structures_four.php" target="_blank" rel="noopener noreferrer">This article</a> explains details of cosmic string simulations.</li>
</ul>
</section>
<div class="mission"><span class="bold">Our Mission:</span> <br />The site is intended as a free educational resource about the frontiers of galaxy formation.</div>
<div class="creation">
<div class="creation_top">
<span class="bold">Creation and Funding:</span>
<br />Content and supervision by Professor Steven Furlanetto, website design by Erika Hoffman, funding and support from NASA NESS, NSF, & UCLA Physics and Astronomy.
</div>
<img src="images/nasa_logo.png" class="nasa" />
<img src="images/nasa_ness.png" class="ness" />
<img src="images/NSF_logo.png" class="nsf" />
<img src="images/Bxd_Wht_PhysicsAstronomy_A.svg" class="ucla" />
</div>
<div class="copyright">
Copyright © 2021
</div>
</div>
</body>
</html>