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Tidal disruption events (TDEs) are bursts of electromagnetic energy that are released when supermassive black holes at the centres of galaxies violently disrupt a star that passes too close 1 . TDEs provide a window through which to study accretion onto supermassive black holes; in some rare cases, this accretion leads to launching of a relativistic jet 2 – 9 , but the necessary conditions are not fully understood. The best-studied jetted TDE so far is Swift J1644+57, which was discovered in γ-rays, but was too obscured by dust to be seen at optical wavelengths. Here we report the optical detection of AT2022cmc, a rapidly fading source at cosmological distance (redshift z  = 1.19325) the unique light curve of which transitioned into a luminous plateau within days. Observations of a bright counterpart at other wavelengths, including X-ray, submillimetre and radio, supports the interpretation of AT2022cmc as a jetted TDE containing a synchrotron ‘afterglow’, probably launched by a supermassive black hole with spin greater than approximately 0.3. Using four years of Zwicky Transient Facility 10 survey data, we calculate a rate of 0.0 2 − 0.01 + 0.04 Gpc −3 yr −1 for on-axis jetted TDEs on the basis of the luminous, fast-fading red component, thus providing a measurement complementary to the rates derived from X-ray and radio observations 11 . Correcting for the beaming angle effects, this rate confirms that approximately 1 per cent of TDEs have relativistic jets. Optical surveys can use AT2022cmc as a prototype to unveil a population of jetted TDEs. A series of early-time, multiwavelength observations of an optical transient, AT2022cmc, indicate that it is a relativistic jet from a tidal disruption event originating from a supermassive black hole.

In the version of this article initially published, there was in an error in the third-to-last sentence of the abstract, now reading, in part, “we calculate a rate of 0.02–0.01 +0.04 Gpc–3 yr–1”, where Gpc was spelled out as gigapascals, not gigaparsecs. Also, the scale label (2″) was missing in the lower-left corner of Fig. 1b. The errors have been corrected in the HTML and PDF versions of the article.

Current research into Galactic star formation has focused primarily on either massive star-forming regions or nearby low-mass regions. We present results from a multi-wavelength survey of Galactic intermediate-mass star-forming regions (IM SFRs). These regions were selected from mid-infrared colors that specify cool dust and large PAH contribution, suggesting that they produce stars up to, but not exceeding, 8 solar masses. Using mid-infrared WISE data we have classified 984 candidate IM SFRs as star-like objects, galaxies, filamentary structures, or blobs/shells. Of the 984 candidates, 616 are probable star-forming regions (62.6%), 128 are filamentary structures (13.0%), 39 are point-like objects of unknown nature (4.0%), and 201 are galaxies (20.4%). Focusing on blobs/shells, the sites of active star-forming regions, we study the stellar and molecular content. First, we perform a pilot study of four of these regions, IRAS 00259+5625, IRAS 00420+5530, IRAS 01080+5717, and IRAS 05380+2020, at Galactic latitudes |b| > 5° using optical spectroscopy from the Wyoming Infrared Observatory along with near-infrared photometry from the Two-Micron All Sky Survey to investigate their stellar content, confirming the intermediate-mass nature of these candidate IM SFRs. Next, we continue the survey with seven additional regions, IRAS 23448+6010, IRAS 22451+6154, IRAS 06464-1650, IRAS 01573+6730, IRAS 01467+5339, IRAS 04275+3519, and IRAS 06293-0931. Then, we conduct a sub-millimeter survey of a sample of 128 IM SFRs, using the Onsala 20-m telescope to observe 13CO (1–0) toward 67 northern IM SFRs, the 12-m Atacama Pathfinder EXperiment telescope to observe 13CO (2–1) toward 22 southern IM SFRs, and incorporate an additional 39 sources from the Boston University Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey which observed 13CO (1–0). We find that IM SFRs have mean a molecular column density of 7.89x10–21 cm–2, a factor of 3.1 lower than that for a sample of high-mass regions, and have a mean 13CO linewidth of 1.84 km/s, a factor of 1.5 lower than that for high-mass regions. Finally, we demonstrate a correlation between 13CO linewidth and infrared luminosity as well as between molecular column density and infrared luminosity for the 13CO sample of intermediate-mass and high-mass regions.

We present upgraded infrastructure for Searches after Gravitational Waves Using ARizona Observatories (SAGUARO) during LIGO, Virgo, and KAGRA's fourth gravitational-wave (GW) observing run (O4). These upgrades implement many of the lessons we learned after a comprehensive analysis of potential electromagnetic counterparts to the GWs discovered during the previous observing run. We have developed a new web-based target and observation manager (TOM) that allows us to coordinate sky surveys, vet potential counterparts, and trigger follow-up observations from one centralized portal. The TOM includes software that aggregates all publicly available information on the light curves and possible host galaxies of targets, allowing us to rule out potential contaminants like active galactic nuclei, variable stars, solar-system objects, and preexisting supernovae, as well as to assess the viability of any plausible counterparts. We have also upgraded our image-subtraction pipeline by assembling deeper reference images and training a new neural network-based real-bogus classifier. These infrastructure upgrades will aid coordination by enabling the prompt reporting of observations, discoveries, and analysis to the GW follow-up community, and put SAGUARO in an advantageous position to discover kilonovae in the remainder of O4 and beyond. Many elements of our open-source software stack have broad utility beyond multimessenger astronomy, and will be particularly relevant in the \"big data\" era of transient discoveries by the Vera C. Rubin Observatory.

We present optical and near-infrared observations of SN~2022crv, a stripped envelope supernova in NGC~3054, discovered within 12 hrs of explosion by the Distance Less Than 40 Mpc Survey. We suggest SN~2022crv is a transitional object on the continuum between SNe Ib and SNe IIb. A high-velocity hydrogen feature ( $\\sim$ $-\\(20,000 -- \\)-\\(16,000 \\)\\rm km\\,s^{-1}\\() was conspicuous in SN~2022crv at early phases, and then quickly disappeared around maximum light. By comparing with hydrodynamic modeling, we find that a hydrogen envelope of \\)\\sim 10^{-3}\\( \\msun{} can reproduce the behaviour of the hydrogen feature observed in SN~2022crv. The early light curve of SN~2022crv did not show envelope cooling emission, implying that SN~2022crv had a compact progenitor with extremely low amount of hydrogen. The analysis of the nebular spectra shows that SN~2022crv is consistent with the explosion of a He star with a final mass of \\)\\sim\\(4.5 -- 5.6 \\msun{} that has evolved from a \\)\\sim\\(16 -- 22 \\msun{} zero-age main sequence star in a binary system with about 1.0 -- 1.7 \\msun{} of oxygen finally synthesized in the core. The high metallicity at the supernova site indicates that the progenitor experienced a strong stellar wind mass loss. In order to retain a small amount of residual hydrogen at such a high metallicity, the initial orbital separation of the binary system is likely larger than \\)\\sim\\(1000~\\)\\rm R_{\\odot}\\(. The near-infrared spectra of SN~2022crv show a unique absorption feature on the blue side of He I line at \\)\\sim\\(1.005~\\)\\mu$ m. This is the first time that such a feature has been observed in a Type Ib/IIb, and could be due to ıonSr2. Further detailed modelling on SN~2022crv can shed light on the progenitor and the origin of the mysterious absorption feature in the near infrared.

This paper describes the software DRAGraces (Data Reduction and Analysis for GRACES), which is a pipeline reducing spectra from GRACES (Gemini Remote Access to the CFHT ESPaDOnS Spectrograph) at the Gemini North Telescope. The code is written in the IDL language. It is designed to find all the GRACES frames in a given directory, automatically determine the list of bias, flat, arc and science frames, and perform the whole reduction and extraction within a few minutes. We compare the output from DRAGraces with that of OPERA, a pipeline developed at CFHT that also can extract GRACES spectra. Both pipelines were developed completely independently, yet they give very similar extracted spectra. They both have their advantages and disadvantages. For instance, DRAGraces is more straightforward and easy to use and is less likely to be derailed by a parameter that needs to be tweaked, while OPERA offers a more careful extraction that can be significantly superior when the highest resolution is required and when the signal-to-noise ratio is low. One should compare both before deciding which one to use for their science. Yet, both pipelines deliver a fairly comparable resolution power (R~52.8k and 36.6k for DRAGraces and R~58k and 40k for OPERA in high and low-resolution spectral modes, respectively), wavelength solution and signal-to-noise ratio per resolution element.

We report on analysis using the James Webb Space Telescope (JWST) to identify a candidate progenitor star of the Type II-plateau supernova SN 2022acko in the nearby, barred spiral galaxy NGC 1300. To our knowledge, our discovery represents the first time JWST has been used to localize a progenitor system in pre-explosion archival Hubble Space Telescope (HST) images. We astrometrically registered a JWST NIRCam image from 2023 January, in which the SN was serendipitously captured, to pre-SN HST F160W and F814W images from 2017 and 2004, respectively. An object corresponding precisely to the SN position has been isolated with reasonable confidence. That object has a spectral energy distribution (SED) and overall luminosity consistent with a single-star model having an initial mass possibly somewhat less than the canonical 8 Msun theoretical threshold for core collapse (although masses as high as 9 Msun for the star are also possible); however, the star's SED and luminosity are inconsistent with that of a super-asymptotic giant branch star which might be a forerunner of an electron-capture SN. The properties of the progenitor alone imply that SN 2022acko is a relatively normal SN II-P, albeit most likely a low-luminosity one. The progenitor candidate should be confirmed with follow-up HST imaging at late times, when the SN has sufficiently faded. This potential use of JWST opens a new era of identifying SN progenitor candidates at high spatial resolution.

We analyze pre-explosion near- and mid-infrared (IR) imaging of the site of SN 2023ixf in the nearby spiral galaxy M101 and characterize the candidate progenitor star. The star displays compelling evidence of variability with a possible period of \\(\\)1000 days and an amplitude of \\( m 0.6\\) mag in extensive monitoring with the Spitzer Space Telescope since 2004, likely indicative of radial pulsations. Variability consistent with this period is also seen in the near-IR \\(J\\) and \\(K_s\\) bands between 2010 and 2023, up to just 10 days before the explosion. Beyond the periodic variability, we do not find evidence for any IR-bright pre-supernova outbursts in this time period. The IR brightness (\\(M_K_s = -10.7\\) mag) and color (\\(J-K_s = 1.6\\) mag) of the star suggest a luminous and dusty red supergiant. Modeling of the phase-averaged spectral energy distribution (SED) yields constraints on the stellar temperature (\\(T_eff = 3500_-1400^+800\\) K) and luminosity (\\( L/L_ = 5.10.2\\)). This places the candidate among the most luminous Type II supernova progenitors with direct imaging constraints, with the caveat that many of these rely only on optical measurements. Comparison with stellar evolution models gives an initial mass of \\(M_init = 174 M_\\). We estimate the pre-supernova mass-loss rate of the star between 3 and 19 yr before explosion from the SED modeling at \\( M 310^-5\\) to \\(310^-4 M_\\) yr\\(^-1\\) for an assumed wind velocity of \\(v_w = 10\\) km s\\(^-1\\), perhaps pointing to enhanced mass loss in a pulsation-driven wind.

We present the Gravitational Wave Treasure Map, a tool to coordinate, visualize, and assess the electromagnetic follow-up of gravitational wave (GW) events. With typical GW localization regions of hundreds to thousands of square degrees and dozens of active follow-up groups, the pursuit of electromagnetic (EM) counterparts is a challenging endeavor, but the scientific payoff for early discovery of any counterpart is clear. With this tool, we provide a website and API interface that allows users to easily see where other groups have searched and better inform their own follow-up search efforts. A strong community of Treasure Map users will increase the overall efficiency of EM counterpart searches and will play a fundamental role in the future of multi-messenger astronomy.