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The Faint Intergalactic-medium redshifted Emission BalloonFIREBall-2
A UV multi-object spectrograph designed to detect the low-z circumgalactic medium in emission via Lyman-alpha, CIV, and OIV.
JPLShouleh NikzadGillian KyneApril Jewell+
CNESJean EvrardJohan MontelEtienne PerotFrederi MircNicholas BrayIsabelle Zenone+
LAMBruno MilliardPhilippe BalardRobert GrangeVincent PicouetDidier VibertPatrick BlanchardMarc Jaquet+
U. ArizonaErika HamdenHaeun ChangAafaque KhanSimran Agarwal+
ColumbiaDavid SchiminovichIgnacio CevallosJose ZorillaJulia GrossNicole MelsoBarbara SantiagoMichele LimonSam GordonHwei Ru Ong+
CaltechChris Martin- PIDrew Miles (2022)Zeren LinDonal O’SullivanNicole LignerMarty Crabill+
U. IowaKeri Hoadley (PS)Jared Termini
FIREBall would not be possible without its amazing Humans!
OutlineThe science that motivates FIREBall
The FIREBall-2 Instrument
& New Technology
FIREBall-2 2018 flight
Looking ahead: FIREBall-2022
Motivation: Where do come from?How do galaxies form?
How do they evolve
(change) with time?
How can we explain the
amazing diversity of
galaxies we see in the
universe?
Image from Galaxy Zoo
Motivation: Probing origins from galaxies There is an evolution in cosmic star formation rates over time:
Madau & Dickinson 2014
Star formation rates steadily increases after the Big Bang (13.8 billion years ago).
The rate of forming stars peaks ~10 billion years ago.
Since ~10 billion years ago, the rate that galaxies form stars has steadily declined.
Illustris
C. Martin, R. Hunt
Galactic Halo(CGM)
Matter is gravitationally-bound within the halo.
Matter flowing in from the Cosmic Web wants to go to the center of these halos, where galaxies form, but...
Tumlinson+ 2017
M82; (HST)
Galactic Halos are complex places!
Illustris
Challenge:We want to see how the smallest particles come together to form into the brightest objects
This is the faint, diffuse gas outside of galaxies
Galactic Halos:The Key to Galaxy Formation
Present dayEarlyUniverse
Why UV?
Hot, energetic, Ionizing;Extreme conditions
Cold/cool/warm gas*, dust; low-mass stars
Multi-phase gas, from cold -> hot;Hottest stars, ionizing sources
Why UV?
adapted fromTumlinson+2012
Tumlinson+2017
Why UV?
How do galaxies interact with their surroundings?Insights from absorption line spectroscopy
Tumlinson, 2017
Looking back in time: Shifting the UV into the Optical
First Direct Detections of galactic halos: Hydrogen-LyɑFirst came narrow-band imagingof the brightest nebulae(“Slug Nebula”, UM287) Cantalupo+2014
Then integral field spectroscopy opened up the field to reveal emission(QSO 1549+19) Martin+2014, CWI/KCWI
Then integral field spectroscopy opened up the field to reveal emission + kinematicsMartin+2019, KCWI (Nature)
First came narrow-band imagingof the brightest nebulae(“Slug Nebula”, UM287) Cantalupo+2014
First Direct Detections of galactic halos: Hydrogen-Lyɑ
Today, Direct Detection surveys of Hydrogen are possibleMUSEUM Survey (MUSE)z ~ 3 - 3.5Arrigoni Battaia+2018
FLASHES Survey (CWI)z ~ 2.3 - 3
O’Sullivan+2020
What we can learn about Halos from Direct DetectionsResult #1:
Nebulae appear to get smalleras the universe ages
What happens to these Lyɑ halos over time?
z ~ 3 - 3.5
z ~ 2.3 - 3
O’Sullivan+2020
Result #2:Nebulae appear to become less
circular over time
z ~ 3 - 3.5
z ~ 2.3 - 3
What happens to these Lyɑ halos over time?
O’Sullivan+2020
What we can learn about Halos from Direct Detections
RECAP: How does hydrogen, the
pristine material from the cosmic web, in halos
change over time?
Result #1:Nebulae appear to get
smaller as the universe ages
Result #2:Nebulae appear to become less circular over time
Halo -> Galaxy Connection:
Accessing UV Light With Suborbital Balloons
Accessing UV Light With Suborbital Balloons
We have access to a narrow window between oxygen molecular bands very high up in the atmosphere (~40 km).
Accessing UV Light With Suborbital Balloons
Scientific Ballooning
Conducted by the
Columbia Scientific
Balloon Facility.
Ballooning allows you
to test out new
technology and
scientific ideas at a
lower cost and risk
than going into space.
Ballooning aroundthe world
T e s t o u t n e w t e c h n o l o g yBalloon telescopes are a perfect test bed for new technology. It’s a near-space environment, but it’s easier to access!
P i l o t s t u d i e s f o rn e w s c i e n c eBalloon telescopes provide an avenue for experimental science with higher risk but higher rewards.
Scientific Benefits ofBalloon AstronomyBalloons (and Rockets!) are used by NASA for a few reasons:
C h e a p e r t h a ns p a c eBalloon missions usually cost a few million dollars at most (and can be re-flown), while a space telescope costs several hundreds of millions of dollars.
A c c e s s t o c e r t a i nW a v e l e n g t h sSome wavelengths are not accessible from the ground, but are accessible from space or high altitudes.
FIREBall-2
FIREBall-2Multi-object spectroscopy:Observes >50 galaxies at oncewith pre-made slit masks
FIREBall-2Multi-object spectroscopy:In practice -->
Each line across the image is its own spectrum!
Illuminated with a Zinc lamp
A s p h e r i c G r a t i n g E l e c t r o n M u l t i p l y i n gC C D s
H i g h U V Q E C C D
FB-2 Technology UpgradesThere are several key technologies which contribute significantly
to FB-2 throughput improvements over FB-1.
!
Readout
Register
Multiplication
Register
Image
Area
Electron Multiplying CCDs
Our work: e2v CCD201-20 device1k x 2k device13 µm pixelsEngineering grade is a frame transferDelta-doped devices are full frame
604 multiplication pixels
Conventional
Photon counting
Figure from N. Konidaris
Num
ber
EMCCD Layout Multiplication mechanism Histogram of a multiplied image
Ideally, this is
your limiting
noise source, but
for very LOW
signal, Read
Noise is a
significant source
of excess noise
Dark Current (DC)
and Clock induced
charge (CIC) <<<
RN
under the right
conditions
Normal CCD
EMCCDCCD
EMCCDs effectively eliminate
read noise, but then one must
deal with DC & CIC
FIREBall’s Gondola
1 . 2 m S i d e r o s t a tProvides x-y coarse
pointing.
R o t a t i o n s t a g eTracks the sky for long exposures
1 m P r i m a r y P a r a b o l af/2.5, Stationary with
Al/MgF2 coating
T i p / T i l t s y s t e mProvides focus adjustment and
centering
THE INSTRUMENT
THE TELESCOPE1-meter diameterParabolic (f/2.5)
1.25-m diametersiderostat (flat)30 elevation,
3 cross-elevation
THE FOCAL CORRECTOR
THE FOCAL CORRECTOR
MOS requires a much larger FOV: 30x30 mmAchromatic Field Corrector for UV (science) & Visible (guider). Unit magnification (x36) to maintain the F/number of the parabola telescope (F/2.5).Predetermined field curvature to flatten field at detector.
THE MASKS + MGS (CU)
THE MASKS + MGS (CU)
Laser-etched slits (50 – 100 um widths).Pre-determined fields.Curved masks to match image plane.
THE SPECTROGRAPH
THE SPECTROGRAPH
All-reflective elements, Al+MgF2 coated.New grating technology (JY) to correct dual Schmidt spherical mirror design.New UV detector technology (EMCCD, δ-doping + multi-layer AR coating [JPL: Nizkad]).
Field CampaignsCampaigns in Fort
Sumner, NM
First was 10 weeks in 2017
(no flight)
Photo by P. Balard, LAM
2017 2018
Sometimes a delay is a good thing…
Red light-blocking optic – Bad Coating
Figure by V. PicouetPSF before replacement After replacement
2017 2018
Field CampaignsCampaigns in Fort
Sumner, NM
First was 10 weeks in 2017
Second was 10 weeks throughout 2018.
Photo by P. Balard, LAM
GoPro video by V. Picouet,
LAM
Photo by P. Balard, LAM
Photo by P. Balard, LAM
Photo by P. Balard, LAM
Prior to launchMechanical testing with
Big Bill and CSBF
Photo by Hwei Ru Ong, Columbia
Flight profile from CSBF
F I R E Ba l l - 2 f l i g h t t r a j e c t or y
Cutdown near Vaughn, NM
1:06 AM, September 23rd
Landing 1 hr later
Photo: Mouser Williams
FIREBall-2 2018 flightA few bad things happened...
The balloon has a hole!
A nice full moon...
Deflated balloon + full moon = stray light everywhere
FIREBall-2 2018 flight
Hoadley+ 2019
Scattered light background >100x expected noise level
FIREBall-2 2018 flight
Hoadley+ 2019
Scattered light background >100x expected noise level
No CGM detections, but we did see <17 mag calibration stars!
FIREBall-2 2018 flightBut good things happened, too!
1. Flight test of delta-doped EMCCD
2. Payload performed beautifully
3. Despite challenging conditions, pointing was < 1” rms in all axes
4. Thermal system successfully removed heat generated by cooler, etc.
5. First flight of a MOS on a balloon
FIREBall 2018 Recovery
- Gondola carbon fiber structure
rods damaged
- UV EMCCD cryocooler busted
- Vacuum Getter charcoal spill
- During flight: scattered light!!!
Landing was hard:- Both large mirrors sustained significant damage
- One FC mirror cracked at bond pad
THE ROAD TO FIREBall-2022Stray light replication
During flight (one image)
Post-flight calibrations (Jan 2019), with visible light
THE ROAD TO FIREBall-2022Critical Stray light paths identified.● Direct off-axis light path to EMCCD from
spectrograph lens:-> enlarge current baffling in-place-> Light trap along spectrograph tank for
visible light diffraction/scatter off grating● Cherenkov emission:
-> protect all non-reflective surfaces withblack (mate) baffling
EMCCD
B. Milliard, S. Pascal
Simran AgarwalUA, grad student
Aafaque KhanUA, grad student
THE ROAD TO FIREBall-2022Additional stray light control:● Gondola baffling:
-> Blacken all shiny surfaces inside gondola-> tent-like structure that opens with
gondola doors
J. Evrard, CNES
THE ROAD TO FIREBall-2022Repairing the Mirror Damage:
Parabola & siderostat checked for surface quality in January 2019
GSFC received both mirrors in May 2019, machined out sharp edges, clamshell fractures, any internal structures forming that could lead to further damage
THE ROAD TO FIREBall-2022Repairing the Mirror Damage:
Parabola & siderostat checked for surface quality in January 2019
GSFC has re-coated both mirrors with Al+MgF2 (mid-2019)
Both mirrors were sent to CNES for install into gondola, Oct 2019
Mirrors now installed in gondola and await shipping to Caltech!
THE ROAD TO FIREBall-2022FC & Spectrograph:
FC mirror damage
1/3 FC(2) mirror bond pads broken as a clamshell fracture.Knocked FC out of (very tight!!) alignment.-> Re-aligning, bonding at new location.
FC mirror alignment jig
THE ROAD TO FIREBall-2022FC & Spectrograph:
Spectrograph: Small (<100 um) adjustments measured to match pre-2018 flight alignment.
Re-optimizing alignment to explore whether spatial PSF can be reduced further (UA)
THE ROAD TO FIREBall-2020Re-optimizing Target Fields & Masks:
Nicole MelsoColumbia, grad student
Vincent PicouetLAM, grad student
Current slit masks don’t leavesufficient room for sky background measurementand subtraction
-> Re-optimizing mask layout+ re-designing flight planfor on/off target exposures
THE ROAD TO FIREBall-2020New QSO-Pair Field & Mask:
Nicole Melso
Columbia, grad student
Vincent Picouet
LAM, grad student
QSOs are extremely luminous -provide a power illumination source for CGM gas!
3x QSOs gives an excellent likelihood of observing CQM gas at low redshift!!
FIREBall-2022We are currently re-building FIREBall-2 for a reflight next year!
Spectrograph build-up:Through 2021Columbia University
Full instrument integration:Jan - May/June 2022Caltech
Fall 2020 flight!September 2022Ft Sumner, NM
Thank you!
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