Webb's First Deep Field: Two Arcs Are the Same Galaxy (NIRISS Emission Spectra)

Stsci_2022-035c_1024

stsci_2022-035c July 12th, 2022

Credit: NASA, ESA, CSA, STScI, Webb ERO Production Team

Want to go on a galactic treasure hunt? Data known as spectra from NASA’s Webb Telescope make it easy to find – and match up – cosmic prizes!

At far left is a near-infrared image of galaxy cluster SMACS 0723. A group of massive galaxies below and to the right of the bright central star have distorted, magnified, and mirrored many galaxies in this field.

By quickly examining the image at left by eye, it becomes clearer that one arc may be made up of two similar-looking galaxies. Their bright central regions match, despite their stretched appearances. These may be lensed galaxies – one galaxy that is mirrored in a second location. Are they the same? Researchers can’t be sure from the image alone – more data are needed to confirm a match.

Scientists do this by gathering spectra, which spread light out so they can fully examine an object’s makeup. Webb’s Near-Infrared Imager and Slitless Spectrograph (NIRISS), which gathers spectra of every object in any field it observes, was pointed at the galaxy cluster to gather more detail. A segment of the NIRISS grism image (an instrument that has a grating, or stair steps, on a prism), at center, shows how ionized oxygen and atomic hydrogen emission lines are distributed along the arc.

Next, the spectra from each of these two galaxies were plotted as graphs, shown at right, to reveal their compositions. The graphs, known as spectra, match, which indicates that these arcs are mirror images of the same galaxy. Webb’s spectra from NIRISS also quickly proved that light from both galaxies was emitted 9.3 billion years ago, further confirming they are one and the same.

Using Webb’s NIRISS is like opening a treasure chest overflowing with spectra. For example, this instrument can disperse the spectra along the image vertically and horizontally. Researchers can use both modes to untangle which lines match each source.

Every object’s image can be transformed into spectra like the two shown above. So even if researchers aren’t intending to study a particular galaxy in the field, they may make a surprise discovery.

For a full array of Webb’s first images and spectra, including downloadable files, please visit: https://webbtelescope.org/news/first-images

NIRISS was contributed by the Canadian Space Agency (CSA). The instrument was designed and built by Honeywell in collaboration with the Université de Montréal and the National Research Council Canada.

Provider: Space Telescope Science Institute

Image Source: https://webbtelescope.org/contents/news-releases/2022/news-2022-035

Curator: STScI, Baltimore, MD, USA

Image Use Policy: http://hubblesite.org/copyright/

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Image Details

Image Type
Chart
Object Name
SMACS 0723-73
Subject - Distant Universe
Galaxy > Grouping > Cluster
Galaxy > Type > Gravitationally Lensed

Distance

Universescale3
4,240,000,000 light years

Position Details

Position (FK5)
RA = 7h 23m 8.6s
DEC = -73° 26’ 59.2”
Constellation
Volans

Color Mapping

  Telescope Spectral Band Wavelength
Webb (NIRISS) Infrared -
Stsci_2022-035c_1280
×
ID
2022-035c
Subject Category
D.5.5.3   D.5.1.8  
Subject Name
SMACS 0723-73
Credits
NASA, ESA, CSA, STScI, Webb ERO Production Team
Release Date
2022-07-12T00:00:00
Lightyears
4,240,000,000
Redshift
0.390
Reference Url
https://webbtelescope.org/contents/news-releases/2022/news-2022-035
Type
Chart
Image Quality
Good
Distance Notes
distance given to cluster at redshift z=0.390
Facility
Webb
Instrument
NIRISS
Color Assignment
Band
Infrared
Bandpass
Central Wavelength
Start Time
Integration Time
Dataset ID
Notes
Coordinate Frame
FK5
Equinox
Reference Value
110.7856779410000030, -73.4497732803999952
Reference Dimension
Reference Pixel
Scale
Rotation
Coordinate System Projection:
Quality
Position
FITS Header
Notes
Creator (Curator)
STScI
URL
http://hubblesite.org
Name
Space Telescope Science Institute Office of Public Outreach
Email
outreach@stsci.edu
Telephone
410-338-4444
Address
3700 San Martin Drive
City
Baltimore
State/Province
MD
Postal Code
21218
Country
USA
Rights
http://hubblesite.org/copyright/
Publisher
STScI
Publisher ID
stsci
Resource ID
STSCI-J-p22035c-f-19084x12100.tif
Metadata Date
2022-07-10T12:35:24-04:00
Metadata Version
1.2
×

 

Detailed color mapping information coming soon...

×
Universescalefull
4,240,000,000 light years