# Presentation: 261109

## AGIS, DELTA, Dark Matter, and Fermilab

***Particle Astrophysics Center***
***Fermi National Accelerator Laboratory***
***dhooper@fnal.gov***

**AGIS, DELTA, Dark Matter, and Fermilab**

*Fermilab Retreat*
*November, 2007*

## The Future of High-Energy Astrophysics

- Ultra-high energy cosmic rays (Auger North, EUSO)
- High and/or ultra-high energy neutrino astronomy       (IceCube-Plus, SALSA, ARIANA, KM3, acoustic detectors)
- Galactic cosmic rays (AMS-02)
- X-ray astronomy
- Gamma ray astronomy (next generation ACTs, superGLAST?)
- WIMP astronomy (*ie*. Super-CDMS, LUX, etc.)

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

## The Future of High-Energy Astrophysics

- Ultra-high energy cosmic rays (Auger North, EUSO)
- High and/or ultra-high energy neutrino astronomy       (IceCube-Plus, SALSA, ARIANA, KM3, acoustic detectors)
- Galactic cosmic rays (AMS-02)
- X-ray astronomy
- Gamma ray astronomy (next generation ACTs, superGLAST?)
- WIMP astronomy (*ie*. Super-CDMS, LUX, etc.)

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

- Approaching practical limit

## The Future of High-Energy Astrophysics

- Ultra-high energy cosmic rays (Auger North, EUSO)
- High and/or ultra-high energy neutrino astronomy       (IceCube-Plus, SALSA, ARIANA, KM3, acoustic detectors)
- Galactic cosmic rays (AMS-02)
- X-ray astronomy
- Gamma ray astronomy (next generation ACTs, superGLAST?)
- WIMP astronomy (*ie*. Super-CDMS, LUX, etc.)

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

- Approaching practical limit

## Dark Matter and the Electroweak Scale

- We expect new physics to appear at or near the EW scale (hierarchy problem, etc.)
- The nature of this new physics is highly constrained by precision measurements of LEP          Suggestive of an additional symmetry (R-parity, T-parity, KK-parity, etc.), naturally (or at least plausibly) leading to a stable new particle
- A stable, neutral, non-colored EW scale 			particle will freeze-out in the early 				universe; For a weak-scale cross section,
- <v> ~ 2 (100 GeV)-2 ~ pb ,
- This leads to, h2 ~ <v>-1 ~ 0.1-1.0
-        ******The “WIMP Miracle”**

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

- WMAP Value!

## The “WIMP Miracle” and Gamma Ray Astronomy

- The WIMP’s annihilation cross section is often written as an expansion in powers of velocity:   v = a+bv2
- If a is not much smaller than b, then the cross section is similar at freeze-out and today, and the annihilation cross section is fixed (modulo co-annihilations, etc.)
- The most important	 					uncertainties in the		 					 gamma ray flux come from 					astrophysics inputs

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

## Two Questions: 

** ****Where To Point Our Telescope? **
**2) What Telescope Should We Build?**

- The Galactic Center
- Dwarf Galaxies
- Other Substructure (*ie*. microhalos)
- Diffuse Emission
- Low threshold or large area?
- Location?
- Field-of-view

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

## Where To Point Our Telescope?

_**First Consideration: Backgrounds**_

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

- Diffuse cosmic rays
- Background Sources
-       -Vary throughout the sky (likely to be less problematic away from the Galactic Center/Plane)

- Hadrons     Gamma-rays       Electrons

## Where To Point Our Telescope?

_**Second Consideration: Signal Brightness**_

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

- Where

- Nearby, dense objects are brightest

## Where To Point Our Telescope?

_**Second Consideration: Signal Brightness**_

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

- Case Example:
- Galactic Center with an NFW Profile,
- 500 GeV WIMP, 3x10-26 cm3/s cross sec.,
- 1010 cm2 effective area, 99.9% hadronic rejection,
- ~200 GeV Threshold, 30 hours observation
-  ~1 detection over diffuse backgrounds
-             (a few hundred signal events)
-  Could be considerably brighter or dimmer
-  Prospects depend critically on
- the halo profile and WIMP properties

## Where To Point Our Telescope?

_**Second Consideration: Signal Brightness**_

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

- Case Example:
- Galactic Center with an NFW Profile,
- 500 GeV WIMP, 3x10-26 cm3/s cross sec.,
- 1010 cm2 effective area, 99.9% hadronic rejection,
- ~200 GeV Threshold, 30 hours observation
-  ~1 detection over diffuse backgrounds
-             (a few hundred signal events)
- Case Example II:
- The Draco or sagittarius dwarf galaxy
-  at most a few dozen signal events,
-     swamped by cosmic ray backgrounds

**Lesson: Before you worry about     signal-to-noise, you need signal!**

## Where To Point Our Telescope?

_**Second Consideration: Signal Brightness**_

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

- Case Example:
- Galactic Center
-  ~1 detection over diffuse backgrounds
-             (a few hundred signal events)
- Case Example II:
- The Draco or sagittarius dwarf galaxy
-  at most a few dozen signal events,
-     swamped by cosmic ray backgrounds
**Caveats: -Yet undiscovered dwarfs (Willman 1, for example)**
**                ****-WIMPs may have unanticipated properties**

## What Telescope Should We Build?

- Gamma rays from dark matter 				annihilations have energies 					which are largely far below the 					WIMP mass
- The most significant weakness 					   of ACTs is that they typically 					have energy thresholds too high					   to observe ~100-300 GeV WIMPs

**What Telescope Should We Build?**

_**Third Consideration: Energy Threshold**_

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

## What Telescope Should We Build?

- By lowering the threshold from 						200 to 20 GeV we gain:
- -500 GeV WIMP, factor of ~10
- -300 GeV WIMP, factor of ~100
- -Below 200 GeV WIMP, detection 				becomes possible (most likely scenario)
**Energy threshold is *****critical***** to studying dark matter!**

**What Telescope Should We Build?**

_**Third Consideration: Energy Threshold**_

## What Telescope Should We Build?

- As low of an energy threshold as possible
- 2) Southern Hemisphere site, to access the Galactic Center
**	****Without both of these two essential features, it is unlikely that the prospects for dark matter detection will be improved significantly with a next generation ACT**** **

**What Telescope Should We Build?**

_**My Opinion:**_

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

## What Telescope Should We Build?

** ****- Array of ~3 ACTs (compared to ~50-100 of AGIS)**
** ****- Low Energy Threshold**
** ****- Southern Hemisphere**
** ****- Dedicated Galactic Center Telescope**
**	**

**What Telescope Should We Build?**

_**Another Option:**_

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

## Best Guess Prospects (NFW, 3x10-26, etc.)

|  | AGIS, North  20 GeV   | AGIS, North 200 GeV | AGIS,  South       20 GeV | AGIS, South, 200 GeV | DELTA | GLAST |
| --- | --- | --- | --- | --- | --- | --- |
| Gal Cen, 100 GeV | NA | NA | Excellent ~20,000 events, ~8 | NA | Fair   ~5,000 events, ~3 | Good   ~4 |
| Gal Cen, 500 GeV | NA | NA | Excellent ~10,000 events, ~4 | Marginal ~300 events, ~1 | Marginal ~2000 events, ~1 | Fair      ~2 |
| Dwarf Gal,    100 GeV | Marginal ~100-1000 events,    ~1 | NA | Marginal ~100-1000 events, ~1 | NA | Poor    ~20-100 events, less than 1 | Poor    less than    1
 |
| Dwarf Gal,    500 GeV | Poor       ~50-500 events,    less than    1 | Poor      ~10 events,  less than 1 | Poor        ~50-500 events, less than 1 | Poor      ~10 events,  less than 1 | Poor    ~10-50 events, less than 1 | Poor    less than    1
 |

**Best Guess Prospects (NFW, 3x10****-26****, etc.)**

## Best Guess Prospects (NFW, 3x10-26, etc.)

|  | AGIS, North  20 GeV   | AGIS, North 200 GeV | AGIS,  South       20 GeV | AGIS, South, 200 GeV | DELTA | GLAST |
| --- | --- | --- | --- | --- | --- | --- |
| Gal Cen, 100 GeV | NA | NA | Excellent ~20,000 events, ~8 | NA | Fair   ~5,000 events, ~3 | Good   ~4 |
| Gal Cen, 500 GeV | NA | NA | Excellent ~10,000 events, ~4 | Marginal ~300 events, ~1 | Marginal ~2000 events, ~1 | Fair      ~2 |
| Dwarf Gal,    100 GeV | Marginal ~100-1000 events,    ~1 | NA | Marginal ~100-1000 events, ~1 | NA | Poor    ~20-100 events, less than 1 | Poor    less than    1
 |
| Dwarf Gal,    500 GeV | Poor       ~50-500 events,    less than    1 | Poor      ~10 events,  less than 1 | Poor        ~50-500 events, less than 1 | Poor      ~10 events,  less than 1 | Poor    ~10-50 events, less than 1 | Poor    less than    1
 |

**Best Guess Prospects (NFW, 3x10****-26****, etc.)**

## The Times They Are A Changin’   (For Dark Matter Searches)

**Dan Hooper**** - ***AGIS and the Future of       **	** **	**        Dark Matter Searches*

- In the next few years, this field will be transformed
- GLAST  Launch in early 2008, data in 2009 (Follow up on unidentified 						          GLAST sources)
- LHC  New physics in 2009? (WIMP-like particle, mass measurement)
- Direct Searches  1-2 orders of magnitude improvement by 2010
- PLANCK  Confirm the synchrotron nature (and dark matter origin) of the excess emission observed by WMAP (*ie*. the “Haze”)
**An experiment coming online in 2009 or later will face a very different set of challenges than today**

## Conclusions

**In the GLAST era, a high ****	****	****	****	****sensitivity, low threshold ACT ****	****	****	****	****	****would be especially valuable**
**AGIS appears to be a ****	****	****	****	****	****	****natural way to address ****	****	****	****	****	****	****these challenges **
**Alternatively, a dedicated, **
**low-threshold Galactic Center **
**telescope (Delta) could be an attractive option**

**Conclusions**

## “Make no little plans; they have no magic to stir men’s blood.” 

*“**Make no little plans; they have no magic to stir men’s blood.” *
*	**	**-Daniel Burnham*

## Widening the Field-Of-View

- Sensitivty to dark matter annihilation can be improved if the angular window around the Galactic Center is opened
- If the background is uniform,  					the highest signal-to-noise 						can be found at angles as 						large as 5-10, depending 					on the halo profile
- An ACT with a wide 						field-of-view can more readily 					study the extension of the 						halo profile

**Dan Hooper**** - ***AGIS and the Future of       **	**	**        Dark Matter Searches*

**Angle From Galactic Center**

**Signal-To-Noise**

- Stoehr, White, Springel, Tormen, Yoshida, 2003

**SWTS**

**NFW**

## Gamma-Rays From Galactic Substructure

**Diemand, Kuhlen, Madau, APJ, astro-ph/0611370**

**Dan Hooper**** - ***AGIS and the Future of       **	** **	**        Dark Matter Searches*

- EW scale dark matter is expected to form structures down to very small (typically ~10-6 M) scales
- Simulations have been used to project gamma-ray sky maps
- If substructure forms with dense inner cusps, it may be possible to detect a number of point sources of dark matter annihilation radiation
- Such sources will require 						scrutiny with very sensitive 					telescopes to conclusively				 		identify as dark matter