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!