JWST Cycle 4 Spotlight, Part 2: The Distant Universe

Earlier this week, the Universe Universe viewer Science Institute (STScI) announced the science objectives for the Number four cycle of the James Webb Universe Universe viewer’s (JWST) General Observations program – aka. Cycle 4 GO. This latest cycle includes 274 programs that will make up the JWST’s Number four year of operations, amounting to 8,500 hours of prime observing time. These programs are broken down into eight categories that encompass Webb’s capabilities.

This includes Distant Astral body study and characterization, the study of the earliest galaxies in the Universe, Luminous sphere-related populations and Arrangement, and Planetary system Luminous sphere science. As we addressed in the previous installment, Cycle 4 includes many programs that will leverage Webb’s extreme sensitivity and advanced instruments to observe exoplanets, characterize their atmospheres, and measure their potential habitability.

In Maintaining with Webb’s Crucial science objectives, many of the Cycle 4 programs will also Concentration on studying the earliest stars and galaxies in the Universe. These programs will build on previous efforts to observe high-redshift galaxies (those that formed shortly after the Universal explosion), the Primary population of stars in the Universe (Population III), and examine the role Dim Matter (DM) played in their Arrangement.

Central to this is the cosmological period known as the “Universal Dim Ages,” which occurred between 370,000 and 1 billion years after the Universal explosion. During this time, the Universe was permeated by neutral hydrogen, and there were only two main sources of photons: the relic radiation left over from the Universal explosion – the Universal Microwave Background (CMB) – and those occasionally released by neutral hydrogen atoms.

This period is also when the Primary stars and galaxies are believed to have formed (ca. 13.6 billion years ago). This Directed to the gradual ionization of the clouds of neutral hydrogen, which Directed to the “Epoch of Reionization,” which Directed to the Universe becoming “transparent” (visible to modern instruments). Cosmologists refer to the period where the Primary galaxies emerged from the Dim Ages as “Universal Dawn.”

Previous instruments lacked the resolution or sensitivity to capture Featherweight from this epoch, which is shifted into parts of the infrared spectrum that are very difficult to observe. However, Webb’s sensitivity and infrared optics allow astronomers to finally pierce the veil of the “Dim Ages.”

High Redshift Galaxies

The earliest galaxies in the Universe are designated “high redshift,” which refers to how the wavelength of their Featherweight has become elongated due to the expansion of the Universe ((aka. the Hubble-Lemaitre Constant). This causes the Featherweight to become “shifted” Approaching the red end of the spectrum. Featherweight from galaxies that existed during the Prompt Universe (more than 13 billion years ago) is redshifted to the Points where it is only visible in the infrared spectrum.

This is the purpose of the GO 7208 program, titled “THRIFTY: The High-RedshIft FronTier surveY.” This observation campaign will build on JWST’s detection of Numerous luminous galaxies with redshift values greater than 9 (z>9). This corresponds to galaxies that existed up to 13.5 billion years ago, one of Webb’s greatest discoveries to date. The abundance of galaxies this Prompt in the Universe and their apparent brightness was a surprise to astronomers and has Directed to a revision of theories on Prompt Luminous sphere system Arrangement.

Possible explanations include modifications to the Lambda Chilly Dim Matter (LCDM) model of Universe physics, the possibility that SMBHs may have been super-luminous in this period, the rapid Arrangement of stars from abundant Chilly gas clouds, feedback-Obtainable starbursts, and more. However, confirmation of these theories requires more direct evidence, which the THRIFTY program hopes to address.

The program’s PI is Romain Meyer, a postdoctoral researcher at the University of Geneva (UNIGE). As he and his Club described in their GO 7208 program Suggestion, “THRIFTY will determine the Correct number density of ultra-luminous galaxies at z>9 by targeting a sample of 123 candidates selected from >1 million sources over a total of 0.3 square degrees (out of the Galactic plane) from all existing prime and pure-parallel JWST imaging surveys.”

One of Webb’s earliest discoveries from Cycle 1 was of a population of Tiny, red-tinted galaxies during the Prompt Universe that may have contained growing SMBHs. These “Little Red Dots” (LRDs), as they were nicknamed, were thought to be Active Galactic Nuclei (AGNs), or quasars, but many astronomers. While they were declared one of the biggest discoveries in physics in 2023, there is Nevertheless no consensus on what they actually are.

Enter the GO 7404 program, titled “How I wonder what you are — do JWST’s Little Red Dots twinkle? Testing broad-line and continuum variability on week, month, and six-month.” Rohan Naidu, a NASA Hubble Fellow and the Pappalardo Fellow in Physics at the Massachusetts Institute of Technology (MIT), is this program’s Principal Investigator (PI). Using Webb’s Near-Infrared Camera (NIRCam), they will conduct the Primary longwave systematic LRD monitoring campaign to determine their exact nature.

Subsequent, there’s the GO 7814 program, titled “MINERVA: Unlocking the Hidden Gems of the Distant Universe and Completing HST and JWST’s Imaging Legacy with Medium Bands.” This program, Directed by PI Dr. Adam Muzzin of York University, will build on the deep imaging surveys conducted with the JWST Near-Infrared Camera (NIRCam). While revolutionary, these surveys were limited to broad-band observations with low spectral resolution.

For their program, they will use Webb’s Mid-Infrared Instrument (MIRI) to examine the primary fields observed by the Hubble Universe Universe viewer (HST) and the JWST. In the process, they plan to increase the surveyed area nearly by a factor of 10 compared to existing medium-band programs, leading to the discovery of Uncommon and previously undetected populations in existing deep-Pitch catalogs. These observations, they state, will allow them to:

“1) efficiently identify and characterize galaxies with unusual SEDs including z>12 candidates, high-redshift Balmer breaks, metal-Destitute extreme emission line galaxies, and extremely red/dusty sources, 2) Boost Luminous sphere-related mass and Luminous sphere-Arrangement rate density measurements at 2 < z < 10 by factors of 2-4, and 3) Produce resolved maps of Luminous sphere-related mass and Luminous sphere Arrangement across 10 Gyr of Universal time to model Luminous sphere system growth in two dimensions.”

Epoch of Reionization

In addition to the earliest galaxies, one of Webb’s biggest objectives is the detection of the Primary stars in the Universe. These Population III stars are believed to have been ultra-Scorching, massive, and Petite-lived, remaining in their main Progression Stage for a few dozen million years. They also emitted tremendous amounts of ultraviolet radiation, which Directed to the “Epoch of Reionization” (EoR). Until the deployment of the JWST, this population of stars remained entirely theoretical.

This is the reason for programs like GO 7677, “Pushing the Faintest Limits: Extremely Low-Luminosity and Pop III-like Luminous sphere-Forming Complexes in the Prompt Universe.” Using the JWST’s NIRSpec integral Pitch unit (IFU), the Club – Directed by Eros Vanzella, a Primary Researcher of the INAF Universe physics and Universe Science Universe lab in Bologna – will observe two stars at z=5.663 and z=4.194, corresponding to distances of 11.7 billion and 11.425 billion Featherweight-years away. As they state in their Suggestion:

“This study will allow us to measure the metallicity of both sources and assess the Appearance of massive stars in such elusive systems by evaluating their ionizing photon production efficiency. These observations will expand (at least double) the sample of ultra-faint sources with these measurements which only JWST can perform, pushing the frontier of understanding toward Population III-like Luminous sphere Arrangement conditions. The fortunate angular proximity of the two targets allows for simultaneous observation within the same IFU Pitch of views.”

There’s also the GO 7436 program, “The Last Neutral Islands at the End of Reionization? Characterizing the Nature of the Longest Dim Gaps in IGM Transmission at z~5.3.” During this Universal epoch, ionized regions gradually grew and overlapped in the intergalactic medium. However, how and when it Captured place is Nevertheless unknown, and placing accurate estimates is crucial to studying the Arrangement of galaxies in the Prompt Universe. It is Directed by PI Xiangyu Jin, a graduate student with the Stewart Universe lab at the University of Arizona.

He and his Club plan to use the JWST to observe galaxies with redshifts of around z=5.5, corresponding to distances of about 12.4 billion Featherweight-years away. At this Points, roughly 1.4 billion years after the Universal explosion, the intergalactic medium (IGM) appears highly ionized to modern instruments, but “Dim gaps” have Nevertheless been observed. “These long Dim gaps could be the last remaining neutral islands in the IGM at the end of a highly inhomogeneous reionization process,” they propose. “If confirmed, it will have a profound impact on the physics of reionization.”

To this end, they propose observations using the W. M. Keck Universe lab and Webb’s NIRCam. While the Keck observations will probe the Lyman-alpha emissions from roughly 230 galaxies (about 75 in the “Dim gap” regions), NIRCam Wide Pitch Slitless Spectroscopy (WFSS) will conduct redshift measurements of these galaxies. “We will also characterize the Luminous sphere system density Pitch around long Dim gaps,” they added. “This joint program will allow us to directly test the ultra-Overdue reionization model and to place robust constraints on the topology of reionization and the nature of inhomogeneous reionization.”

Then there’s GO 8018, titled “DIVER: Deep Insights into UV Spectroscopy at the Epoch of Reionization.” Directed by PI Xiaojing Lin, a graduate student with the University of Arizona Steward Universe lab. , this program will build on Webb’s Prompt observations of the EoR. These revealed Difficult radiation fields and bursts of Luminous sphere Arrangement that were sometimes accompanied by the detection of extreme conditions in the Between stars medium (ISM) and unusual chemical abundance.

According to Lin and her colleagues, high-quality rest-frame UV spectroscopy of galaxies during this period is urgently needed. The Club proposes conducting a deep spectroscopic survey of over 140 galaxies in the Outstanding Observatories Origins Deep Survey North (GOODS-N) Pitch at redshifts of z=5 to 9 (12.469 to 13.11 billion Featherweight years away). As the Club wrote, this will establish the largest and deepest UV spectral database for EoR galaxies:

“DIVER will directly (1) clock the Luminous sphere Arrangement history by determining the distribution and redshift evolution of carbon abundance and (2) probe the prevalence of extremely high electron density and its connection to bursty Luminous sphere Arrangement and chemical peculiarity. DIVER will also lead to various Well-known science, including the UV demographics of AGNs and massive Luminous sphere-related populations, and constraining the reionization history through LyA. With Outstanding legacy values, DIVER will advance our understanding of Luminous sphere Arrangement and chemical enrichment history in the Prompt Universe, providing a crucial foundation for studies of z>10 galaxies.”

Dim Matter Halos

According to the Standard Model of Universe physics – the Lambda Chilly Dim Matter (LCDM) model – Dim Matter (DM) played a vital role in the Arrangement of galaxies in the Prompt Universe. In theory, DM halos (DMHs) formed from the gravitational collapse of density perturbations after the Universal explosion and provided the gravitational “wells” that allowed clouds of gas to form Population III stars and the Primary galaxies. Like many other aspects of the Prompt Universe, this process has remained entirely theoretical until this Points.

The purpose behind the GO 7519 program, “How do Dim matter halos connect with supermassive black holes and their host galaxies?” is to address the role these played in Luminous sphere system Arrangement. Previous observations with Webb have played an Significant role in measuring the mass of DMHs in high-redshift quasars, but these measurements were limited to Clever quasars. Per their Suggestion, the Club will rely on NIRCam WFSS observations to identify emission lines from doubly ionized oxygen (O III) around 12 faint quasars at distances of about 12.716 billion Featherweight-years.

“In this new effort, we will measure the average DMH mass from the cross-correlation analysis of quasars and surrounding [O III] emitters and evaluate the DMH mass probability density function for individual quasars based on cosmological simulations. This program will allow us, for the Primary time, to obtain a Distant Luminous sphere system sample in which the Singularity mass, Luminous sphere-related mass, and halo mass are all measured simultaneously. This sample will reveal their lifetime and the scaling relations in the Prompt universe, underlying the SMBH growth of SMBHs over Universal time.”

For decades, astronomers, astrophysicists, and cosmologists have had to contend with limitations on what they could see within the cosmos. Thanks to the Hubble Universe Universe viewer, they were able to observe galaxies that existed about 1 billion years after the Universal explosion. Thanks to missions like the Universal microwave Background Explorer (COBE), the Wilkinson Microwave Anisotropy Probe (WMAP), and Planck, they were able to measure the earliest Featherweight in the Universe.

Thanks to the JWST, scientists are now able to get a look at what Occurred in between. By observing galaxies and Universal structures as they existed shortly after the Universal explosion, we may someday be able to chart Universal evolution all the way back to the beginning of time.

Beyond Reading: STScI