The logarithmic scale of the artist perception of the observable universe. The Solar System gives way to the Galaxy, which gives way to nearby galaxies that then give way to the large-scale structure and hot, dense creature of the Big Bang in the vicinity. Every line of sight we can observe contains all these eras, but the search for the most distant observed object will not be completed until we have mapped the entire Universe. (Offer: Pablo Carlos Budassi; Unmismoobjetivo / Wikimedia Commons) This galaxy, HD1, has just been announced as the newest, most distant galaxy it has ever seen. Appearing here with purple arrows, this tiny red object, which can barely be seen without markers on it, may represent the most distant object currently known in the Universe: HD1. However, its distance has not yet been definitively determined. (Offer: Harikane et al.) At 330 million years old, it is currently 33 billion light-years away: the farthest it has ever seen. Light emitted from any galaxy emitted after the onset of the Big Bang 13.8 billion years ago would have reached us by now, at a distance of about 46.1 billion light-years. But light from the first, farthest galaxies will be blocked by interfering matter and shifted to red by the expanding Universe. Both represent serious challenges for detection and warn us, drawing definitive conclusions about their distance without the appropriate, necessary data. (Offer: F. Summers, A. Pagan, L. Hustak, G. Bacon, Z. Levay and L. Frattere (STScI)) This could break the old GN-z11 record: 407 million years old and 32 billion light-years away. Part of the GOODS-N field, which contains the galaxy GN-z11, the most distant galaxy ever observed. At a displacement of red 11.1, a distance of 32.1 billion light-years, and an estimated age of the Universe of 407 million light-years at the time this light is emitted, this is the farthest back we have ever seen a bright object in the universe. Hubble spectroscopic confirmation was key. without it, we would have to remain skeptical. (Credit: NASA, ESA, G. Bacon (STScI), A. Feild (STScI), P. Oesch (Yale)) If so, it’s an exciting find: bright, luminous and possibly the home of the first truly virgin stars. The first stars and galaxies to form must be the home of the population of Population III: stars consisting only of the elements that first formed during the hot Big Bang, which is 99.999999% exclusively hydrogen and helium. Such a population has never been seen or confirmed, but some hope that HD1 will contain it. (Offer: Pablo Carlos Budassi / Wikimedia Commons) But there is a strong possibility that the HD1 is not the widely reported record. Although there are large, extremely distant, very red, and even infrared galaxies, such as those found here in the Hubble eXtreme Deep Field, many of these candidate galaxies have been shown to be either inherently red and / or closer, not the super- distant objects we hoped they were. Without spectroscopic confirmation, making fun of ourselves for the cosmic distance of an object is an unfortunate but common occurrence. (Credit: NASA, ESA, R. Bouwens and G. Illingsworth (UC, Santa Cruz)) Yes, it is extremely red, without all the light of the short wave. This figure shows various photometric filters (top) and HD1 images that reveal or do not reveal, as well as two different adjustments to the photometric data. Note that although the high displacement adjustment is superior, there is no spectroscopic confirmation of the distance of the galaxy HD1. (Offer: Y. Harikane et al., ApJ, 2022) Only long-wavelength photometric filters do not reveal the object at all. Before a sufficient number of stars are formed, neutral atoms remain in the intergalactic medium of the Universe, where they are extremely effective in blocking the ultraviolet and visible light of the stars. Without spectroscopic confirmation, as we have for GN-z11 but not for HD1, caution should be exercised. (Offer: Harikane et al., NASA, EST and P. Oesch / Yale) This is in line with an object behind the “wall of neutrals” before re-ionization. Schematic diagram of the history of the Universe, which points to the renaissance. Before the formation of stars or galaxies, the Universe was full of neutral individuals blocking light. Most of the Universe is being re-deionized only 550 million years later, with some areas achieving complete re-deionization sooner and others later. The first big waves of renaissance begin to occur at the age of about 250 million years, while some lucky stars may form just 50 to 100 million years after the Big Bang. With the right tools, such as the James Webb Space Telescope, we can begin to discover the first galaxies. (Credit: SG Djorgovski et al., Caltech; Caltech Digital Media Center) But only spectroscopy can determine the redshift of a galaxy with absolute certainty. Only by refracting light from a distant object at its wavelengths and detecting the signature of atomic or ionic electron transitions that can be associated with a redshift, and therefore the expanding Universe, can a definite shift to red be achieved? (and hence distance) to reach. These components are missing for HD1 and HD2 today. (Offer: Vesto Slipher, 1917, Proc. Amer. Phil. Soc.) Multiple spectral lines, associated with quantum transitions, reveal how strongly emitted light shifts to red from the expanding Universe. This simplified animation shows how light shifts to red and how distances between unbound objects change over time in the expanding Universe. Only by relating the wavelength of the emitted light to the observed light can the displacement to red be really measured with certainty. (Credit: Rob Knop) For HD1, there is only one candidate line and the detection value is below the 5-s limit. In all the spectra obtained from our most powerful observatories, including ALMA, the galaxy HD1, only one test signature appears for one line: for a double ionized oxygen line. His self-confidence does not reach the “gold standard” required to announce a discovery. (Offer: Y. Harikane et al., ApJ, 2022) The “other” remote contender, HD2, has no spectral lines at all. Exposures to different photometric zones (above) of the candidate galaxy HD2, along with two possible spectral adjustments (curves) to the data points (red). Note that, although a high redshift solution (z = 12) is preferred over a low redshift interpretation (z = 3.5), both are possible and clear signature spectroscopy is not available. (Offer: Y. Harikane et al., ApJ, 2022) Care must be taken until spectroscopic confirmation is reached, as distances cannot be determined decisively. The full published spectrum of the candidate galaxy HD1 shows no definitive spectral line detections. The red arrow corresponds to the candidate signal of a double ionized oxygen line. Without definitive data, we can not responsibly conclude that this is, in fact, the most distant galaxy we have ever seen. It may not be like that at all. (Offer: Y. Harikane et al., ApJ, 2022) For the most part, Mute Monday tells an astronomical story in pictures, images and no more than 200 words. Speak less? Smile more.
