Pub Date : 2023-06-26DOI: 10.3847/2041-8213/acdef1
S. Paudel, Suk-Jin Yoon, O. Bait, C. Sengupta, Woong-Bae G. Zee, D. Chhatkuli, B. Adhikari, B. Aryal
We report a rare astrophysical phenomenon, in which an early-type dwarf galaxy (dE), LEDA 1915372, is accreting gas from a nearby star-forming dwarf galaxy, MRK 0689, and is rejuvenating star formation activity at the center. Both LEDA 1915372 and MRK 0689 have similar brightness of M r = −16.99 and −16.78 mag, respectively. They are located in a small group environment, separated by a sky-projected distance of 20.27 kpc (up to 70 kpc in three dimension), and have a relative line-of-sight radial velocity of 6 km s−1. The observation of 21 cm emission with the Giant Metrewave Radio Telescope provides strong evidence of interaction between the pair of dwarf galaxies in terms of neutral hydrogen (Hi) morphology and kinematics. In particular, the Hi map reveals that the two galaxies are clearly connected by a gas bridge, and the gas components of both LEDA 1915372 and MRK 0689 share a common direction of rotation. We also find that the Hi emission peak deviates from LEDA 1915372 toward its optical blue plume, suggesting a tidal origin of ongoing central star formation. Our findings provide a new path to the formation of blue-cored dEs.
{"title":"Rejuvenating Star Formation Activity in an Early-type Dwarf Galaxy, LEDA 1915372, with Accreted H i Gas","authors":"S. Paudel, Suk-Jin Yoon, O. Bait, C. Sengupta, Woong-Bae G. Zee, D. Chhatkuli, B. Adhikari, B. Aryal","doi":"10.3847/2041-8213/acdef1","DOIUrl":"https://doi.org/10.3847/2041-8213/acdef1","url":null,"abstract":"We report a rare astrophysical phenomenon, in which an early-type dwarf galaxy (dE), LEDA 1915372, is accreting gas from a nearby star-forming dwarf galaxy, MRK 0689, and is rejuvenating star formation activity at the center. Both LEDA 1915372 and MRK 0689 have similar brightness of M r = −16.99 and −16.78 mag, respectively. They are located in a small group environment, separated by a sky-projected distance of 20.27 kpc (up to 70 kpc in three dimension), and have a relative line-of-sight radial velocity of 6 km s−1. The observation of 21 cm emission with the Giant Metrewave Radio Telescope provides strong evidence of interaction between the pair of dwarf galaxies in terms of neutral hydrogen (Hi) morphology and kinematics. In particular, the Hi map reveals that the two galaxies are clearly connected by a gas bridge, and the gas components of both LEDA 1915372 and MRK 0689 share a common direction of rotation. We also find that the Hi emission peak deviates from LEDA 1915372 toward its optical blue plume, suggesting a tidal origin of ongoing central star formation. Our findings provide a new path to the formation of blue-cored dEs.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125824440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-26DOI: 10.3847/2041-8213/acec4a
O. Gottlieb, Danat Issa, J. Jacquemin-Ide, M. Liska, A. Tchekhovskoy, F. Foucart, D. Kasen, R. Perna, E. Quataert, B. Metzger
The ongoing LIGO–Virgo–KAGRA observing run O4 provides an opportunity to discover new multimessenger events, including binary neutron star (BNS) mergers such as GW170817 and the highly anticipated first detection of a multimessenger black hole–neutron star (BH–NS) merger. While BNS mergers were predicted to exhibit early optical emission from mildly relativistic outflows, it has remained uncertain whether the BH–NS merger ejecta provides the conditions for similar signals to emerge. We present the first modeling of early near-ultraviolet/optical emission from mildly relativistic outflows in BH–NS mergers. Adopting optimal binary properties, a mass ratio of q = 2, and a rapidly rotating BH, we utilize numerical relativity and general relativistic magnetohydrodynamic (GRMHD) simulations to follow the binary’s evolution from premerger to homologous expansion. We use an M1 neutrino transport GRMHD simulation to self-consistently estimate the opacity distribution in the outflows and find a bright near-ultraviolet/optical signal that emerges due to jet-powered cocoon cooling emission, outshining the kilonova emission at early time. The signal peaks at an absolute magnitude of ∼−15 a few hours after the merger, longer than previous estimates, which did not consider the first principles–based jet launching. By late 2024, the Rubin Observatory will have the capability to track the entire signal evolution or detect its peak up to distances of ≳1 Gpc. In 2026, ULTRASAT will conduct all-sky surveys within minutes, detecting some of these events within ∼200 Mpc. The BH–NS mergers with higher mass ratios or lower BH spins would produce shorter and fainter signals.
{"title":"Hours-long Near-UV/Optical Emission from Mildly Relativistic Outflows in Black Hole–Neutron Star Mergers","authors":"O. Gottlieb, Danat Issa, J. Jacquemin-Ide, M. Liska, A. Tchekhovskoy, F. Foucart, D. Kasen, R. Perna, E. Quataert, B. Metzger","doi":"10.3847/2041-8213/acec4a","DOIUrl":"https://doi.org/10.3847/2041-8213/acec4a","url":null,"abstract":"The ongoing LIGO–Virgo–KAGRA observing run O4 provides an opportunity to discover new multimessenger events, including binary neutron star (BNS) mergers such as GW170817 and the highly anticipated first detection of a multimessenger black hole–neutron star (BH–NS) merger. While BNS mergers were predicted to exhibit early optical emission from mildly relativistic outflows, it has remained uncertain whether the BH–NS merger ejecta provides the conditions for similar signals to emerge. We present the first modeling of early near-ultraviolet/optical emission from mildly relativistic outflows in BH–NS mergers. Adopting optimal binary properties, a mass ratio of q = 2, and a rapidly rotating BH, we utilize numerical relativity and general relativistic magnetohydrodynamic (GRMHD) simulations to follow the binary’s evolution from premerger to homologous expansion. We use an M1 neutrino transport GRMHD simulation to self-consistently estimate the opacity distribution in the outflows and find a bright near-ultraviolet/optical signal that emerges due to jet-powered cocoon cooling emission, outshining the kilonova emission at early time. The signal peaks at an absolute magnitude of ∼−15 a few hours after the merger, longer than previous estimates, which did not consider the first principles–based jet launching. By late 2024, the Rubin Observatory will have the capability to track the entire signal evolution or detect its peak up to distances of ≳1 Gpc. In 2026, ULTRASAT will conduct all-sky surveys within minutes, detecting some of these events within ∼200 Mpc. The BH–NS mergers with higher mass ratios or lower BH spins would produce shorter and fainter signals.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114579751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-26DOI: 10.3847/2041-8213/aceeff
O. Gottlieb, Danat Issa, J. Jacquemin-Ide, M. Liska, F. Foucart, A. Tchekhovskoy, B. Metzger, E. Quataert, R. Perna, D. Kasen, Matthew D. Duez, Lawrence E. Kidder, H. Pfeiffer, M. Scheel
We present the first numerical simulations that track the evolution of a black hole–neutron star (BH–NS) merger from premerger to r ≳ 1011 cm. The disk that forms after a merger of mass ratio q = 2 ejects massive disk winds (3–5 × 10−2 M ⊙). We introduce various postmerger magnetic configurations and find that initial poloidal fields lead to jet launching shortly after the merger. The jet maintains a constant power due to the constancy of the large-scale BH magnetic flux until the disk becomes magnetically arrested (MAD), where the jet power falls off as L j ∼ t −2. All jets inevitably exhibit either excessive luminosity due to rapid MAD activation when the accretion rate is high or excessive duration due to delayed MAD activation compared to typical short gamma-ray bursts (sGRBs). This provides a natural explanation for long sGRBs such as GRB 211211A but also raises a fundamental challenge to our understanding of jet formation in binary mergers. One possible implication is the necessity of higher binary mass ratios or moderate BH spins to launch typical sGRB jets. For postmerger disks with a toroidal magnetic field, dynamo processes delay jet launching such that the jets break out of the disk winds after several seconds. We show for the first time that sGRB jets with initial magnetization σ 0 > 100 retain significant magnetization (σ ≫ 1) at r > 1010 cm, emphasizing the importance of magnetic processes in the prompt emission. The jet–wind interaction leads to a power-law angular energy distribution by inflating an energetic cocoon whose emission is studied in a companion paper.
{"title":"Large-scale Evolution of Seconds-long Relativistic Jets from Black Hole–Neutron Star Mergers","authors":"O. Gottlieb, Danat Issa, J. Jacquemin-Ide, M. Liska, F. Foucart, A. Tchekhovskoy, B. Metzger, E. Quataert, R. Perna, D. Kasen, Matthew D. Duez, Lawrence E. Kidder, H. Pfeiffer, M. Scheel","doi":"10.3847/2041-8213/aceeff","DOIUrl":"https://doi.org/10.3847/2041-8213/aceeff","url":null,"abstract":"We present the first numerical simulations that track the evolution of a black hole–neutron star (BH–NS) merger from premerger to r ≳ 1011 cm. The disk that forms after a merger of mass ratio q = 2 ejects massive disk winds (3–5 × 10−2 M ⊙). We introduce various postmerger magnetic configurations and find that initial poloidal fields lead to jet launching shortly after the merger. The jet maintains a constant power due to the constancy of the large-scale BH magnetic flux until the disk becomes magnetically arrested (MAD), where the jet power falls off as L j ∼ t −2. All jets inevitably exhibit either excessive luminosity due to rapid MAD activation when the accretion rate is high or excessive duration due to delayed MAD activation compared to typical short gamma-ray bursts (sGRBs). This provides a natural explanation for long sGRBs such as GRB 211211A but also raises a fundamental challenge to our understanding of jet formation in binary mergers. One possible implication is the necessity of higher binary mass ratios or moderate BH spins to launch typical sGRB jets. For postmerger disks with a toroidal magnetic field, dynamo processes delay jet launching such that the jets break out of the disk winds after several seconds. We show for the first time that sGRB jets with initial magnetization σ 0 > 100 retain significant magnetization (σ ≫ 1) at r > 1010 cm, emphasizing the importance of magnetic processes in the prompt emission. The jet–wind interaction leads to a power-law angular energy distribution by inflating an energetic cocoon whose emission is studied in a companion paper.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129723773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-25DOI: 10.3847/2041-8213/ace42b
F. Arrigoni Battaia, A. Obreja, T. Costa, E. Farina, Zheng Cai
Cool (T ∼ 104 K) gas is commonly observed around z > 2 quasars as traced by extended Lyα emission. These large-scale nebulae are usually studied using circularly averaged surface-brightness profiles, which suppress information on morphological differences. Here, we revisit the Lyα nebulae around 78 z ∼ 2–3 quasars to obtain a novel estimate of their area and asymmetry using a common redshift-corrected surface-brightness threshold. We find a luminosity–area relation of the form log(LLyαNeb)=a1log(AreaNeb)+a0 . Most nebulae are symmetric and bright, the most lopsided ones being the faintest and less extended. The enormous Lyα nebulae, asymmetric due to the presence of active companions, are the exceptions to this trend. By using simulations able to reproduce z ∼ 6 quasars’ nebulae, we show that the observed relation should not vary with redshift. Finally, we discuss possible mechanisms that drive the relation and future work needed to constrain them.
{"title":"The Luminosity–Area Relation of z > 2 Quasars’ Lyα Nebulae","authors":"F. Arrigoni Battaia, A. Obreja, T. Costa, E. Farina, Zheng Cai","doi":"10.3847/2041-8213/ace42b","DOIUrl":"https://doi.org/10.3847/2041-8213/ace42b","url":null,"abstract":"Cool (T ∼ 104 K) gas is commonly observed around z > 2 quasars as traced by extended Lyα emission. These large-scale nebulae are usually studied using circularly averaged surface-brightness profiles, which suppress information on morphological differences. Here, we revisit the Lyα nebulae around 78 z ∼ 2–3 quasars to obtain a novel estimate of their area and asymmetry using a common redshift-corrected surface-brightness threshold. We find a luminosity–area relation of the form log(LLyαNeb)=a1log(AreaNeb)+a0 . Most nebulae are symmetric and bright, the most lopsided ones being the faintest and less extended. The enormous Lyα nebulae, asymmetric due to the presence of active companions, are the exceptions to this trend. By using simulations able to reproduce z ∼ 6 quasars’ nebulae, we show that the observed relation should not vary with redshift. Finally, we discuss possible mechanisms that drive the relation and future work needed to constrain them.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124237115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-23DOI: 10.3847/2041-8213/acdfd0
C. Law, A. Booth, K. Öberg
Planets form in dusty, gas-rich disks around young stars, while at the same time, the planet formation process alters the physical and chemical structure of the disk itself. Embedded planets will locally heat the disk and sublimate volatile-rich ices, or in extreme cases, result in shocks that sputter heavy atoms such as Si from dust grains. This should cause chemical asymmetries detectable in molecular gas observations. Using high-angular-resolution ALMA archival data of the HD 169142 disk, we identify compact SO J = 88 − 77 and SiS J = 19 − 18 emission coincident with the position of a ∼ 2 M Jup planet seen as a localized, Keplerian NIR feature within a gas-depleted, annular dust gap at ≈38 au. The SiS emission is located along an azimuthal arc and has a morphology similar to that of a known 12CO kinematic excess. This is the first tentative detection of SiS emission in a protoplanetary disk and suggests that the planet is driving sufficiently strong shocks to produce gas-phase SiS. We also report the discovery of compact 12CO and 13CO J = 3 − 2 emission coincident with the planet location. Taken together, a planet-driven outflow provides the best explanation for the properties of the observed chemical asymmetries. We also resolve a bright, azimuthally asymmetric SO ring at ≈24 au. While most of this SO emission originates from ice sublimation, its asymmetric distribution implies azimuthal temperature variations driven by a misaligned inner disk or planet–disk interactions. Overall, the HD 169142 disk shows several distinct chemical signatures related to giant planet formation and presents a powerful template for future searches of planet-related chemical asymmetries in protoplanetary disks.
{"title":"SO and SiS Emission Tracing an Embedded Planet and Compact 12CO and 13CO Counterparts in the HD 169142 Disk","authors":"C. Law, A. Booth, K. Öberg","doi":"10.3847/2041-8213/acdfd0","DOIUrl":"https://doi.org/10.3847/2041-8213/acdfd0","url":null,"abstract":"Planets form in dusty, gas-rich disks around young stars, while at the same time, the planet formation process alters the physical and chemical structure of the disk itself. Embedded planets will locally heat the disk and sublimate volatile-rich ices, or in extreme cases, result in shocks that sputter heavy atoms such as Si from dust grains. This should cause chemical asymmetries detectable in molecular gas observations. Using high-angular-resolution ALMA archival data of the HD 169142 disk, we identify compact SO J = 88 − 77 and SiS J = 19 − 18 emission coincident with the position of a ∼ 2 M Jup planet seen as a localized, Keplerian NIR feature within a gas-depleted, annular dust gap at ≈38 au. The SiS emission is located along an azimuthal arc and has a morphology similar to that of a known 12CO kinematic excess. This is the first tentative detection of SiS emission in a protoplanetary disk and suggests that the planet is driving sufficiently strong shocks to produce gas-phase SiS. We also report the discovery of compact 12CO and 13CO J = 3 − 2 emission coincident with the planet location. Taken together, a planet-driven outflow provides the best explanation for the properties of the observed chemical asymmetries. We also resolve a bright, azimuthally asymmetric SO ring at ≈24 au. While most of this SO emission originates from ice sublimation, its asymmetric distribution implies azimuthal temperature variations driven by a misaligned inner disk or planet–disk interactions. Overall, the HD 169142 disk shows several distinct chemical signatures related to giant planet formation and presents a powerful template for future searches of planet-related chemical asymmetries in protoplanetary disks.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124847625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-21DOI: 10.3847/2041-8213/ace115
Ananyo Bhattacharya, Cheng Li, S. Atreya, P. Steffes, S. Levin, S. Bolton, T. Guillot, P. Gupta, A. Ingersoll, J. Lunine, G. Orton, F. Oyafuso, J. Waite, A. Bellotti, M. Wong
Water and ammonia vapors are known to be the major sources of spectral absorption at pressure levels observed by the microwave radiometer (MWR) on Juno. However, the brightness temperatures and limb darkening observed by the MWR at its longest-wavelength channel of 50 cm (600 MHz) in the first nine perijove passes indicate the existence of an additional source of opacity in the deep atmosphere of Jupiter (pressures beyond 100 bar). The absorption properties of ammonia and water vapor, and their relative abundances in Jupiter’s atmosphere, do not provide sufficient opacity in the deep atmosphere to explain the 600 MHz channel observation. Here we show that free electrons due to the ionization of alkali metals, i.e., sodium and potassium, with subsolar metallicity, [M/H] (log-based 10 relative concentration to solar) in the range of [M/H] = −2 to [M/H] = −5, can provide the missing source of opacity in the deep atmosphere. If the alkali metals are not the source of additional opacity in the MWR data, then their metallicity at 1000 bars can only be even lower. This upper bound of −2 on the metallicity of the alkali metals contrasts with the other heavy elements—C, N, S, Ar, Kr, and Xe—that are all enriched relative to their solar abundances, having a metallicity of approximately +0.5.
{"title":"Highly Depleted Alkali Metals in Jupiter’s Deep Atmosphere","authors":"Ananyo Bhattacharya, Cheng Li, S. Atreya, P. Steffes, S. Levin, S. Bolton, T. Guillot, P. Gupta, A. Ingersoll, J. Lunine, G. Orton, F. Oyafuso, J. Waite, A. Bellotti, M. Wong","doi":"10.3847/2041-8213/ace115","DOIUrl":"https://doi.org/10.3847/2041-8213/ace115","url":null,"abstract":"Water and ammonia vapors are known to be the major sources of spectral absorption at pressure levels observed by the microwave radiometer (MWR) on Juno. However, the brightness temperatures and limb darkening observed by the MWR at its longest-wavelength channel of 50 cm (600 MHz) in the first nine perijove passes indicate the existence of an additional source of opacity in the deep atmosphere of Jupiter (pressures beyond 100 bar). The absorption properties of ammonia and water vapor, and their relative abundances in Jupiter’s atmosphere, do not provide sufficient opacity in the deep atmosphere to explain the 600 MHz channel observation. Here we show that free electrons due to the ionization of alkali metals, i.e., sodium and potassium, with subsolar metallicity, [M/H] (log-based 10 relative concentration to solar) in the range of [M/H] = −2 to [M/H] = −5, can provide the missing source of opacity in the deep atmosphere. If the alkali metals are not the source of additional opacity in the MWR data, then their metallicity at 1000 bars can only be even lower. This upper bound of −2 on the metallicity of the alkali metals contrasts with the other heavy elements—C, N, S, Ar, Kr, and Xe—that are all enriched relative to their solar abundances, having a metallicity of approximately +0.5.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127577279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-21DOI: 10.3847/2041-8213/ace053 10.3847/2041-8213/ace053
M. Mehdipour, G. Kriss, J. Kaastra, E. Costantini, J. Mao
We report on a remarkable change in the spectral energy distribution (SED) of Mrk 841, providing new insights on how the soft X-ray excess emission in active galactic nuclei (AGNs) is produced. By Swift monitoring of a sample of Seyfert-1 galaxies, we found an X-ray spectral hardening event in Mrk 841. We thereby triggered our XMM-Newton, NuSTAR, and Hubble Space Telescope observations in 2022 to study this event. Our previous investigations of such events in other AGNs had shown that they are caused by obscuring winds. However, the event in Mrk 841 has different spectral characteristics and origin. We find it is the soft X-ray excess component that has become dimmer. This is, importantly, accompanied by a similar decline in the optical/UV continuum, suggesting a connection to the soft X-ray excess. In contrast, there is relatively little change in the X-ray power law and the reflection components. Our SED modeling suggests that the soft X-ray excess is the high-energy extension of the optical/UV disk emission, produced by warm Comptonization. We find the temperature of the disk dropped in 2022, explaining the observed SED dimming. We then examined the Swift data, taken over 15 yr, to further decipher the UV and X-ray variabilities of Mrk 841. A significant relation between the variabilities of the X-ray spectral hardness and that of the UV continuum is found, again suggesting that the soft excess and the disk emission are interlinked. This is readily explicable if the soft excess is produced by warm Comptonization.
{"title":"Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-Ray Excess","authors":"M. Mehdipour, G. Kriss, J. Kaastra, E. Costantini, J. Mao","doi":"10.3847/2041-8213/ace053 10.3847/2041-8213/ace053","DOIUrl":"https://doi.org/10.3847/2041-8213/ace053 10.3847/2041-8213/ace053","url":null,"abstract":"We report on a remarkable change in the spectral energy distribution (SED) of Mrk 841, providing new insights on how the soft X-ray excess emission in active galactic nuclei (AGNs) is produced. By Swift monitoring of a sample of Seyfert-1 galaxies, we found an X-ray spectral hardening event in Mrk 841. We thereby triggered our XMM-Newton, NuSTAR, and Hubble Space Telescope observations in 2022 to study this event. Our previous investigations of such events in other AGNs had shown that they are caused by obscuring winds. However, the event in Mrk 841 has different spectral characteristics and origin. We find it is the soft X-ray excess component that has become dimmer. This is, importantly, accompanied by a similar decline in the optical/UV continuum, suggesting a connection to the soft X-ray excess. In contrast, there is relatively little change in the X-ray power law and the reflection components. Our SED modeling suggests that the soft X-ray excess is the high-energy extension of the optical/UV disk emission, produced by warm Comptonization. We find the temperature of the disk dropped in 2022, explaining the observed SED dimming. We then examined the Swift data, taken over 15 yr, to further decipher the UV and X-ray variabilities of Mrk 841. A significant relation between the variabilities of the X-ray spectral hardness and that of the UV continuum is found, again suggesting that the soft excess and the disk emission are interlinked. This is readily explicable if the soft excess is produced by warm Comptonization.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133699698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-20DOI: 10.3847/2041-8213/ace32c
Samuel A Beiler, M. Cushing, D. Kirkpatrick, A. Schneider, S. Mukherjee, M. Marley
We present the first JWST spectral energy distribution of a Y dwarf. This spectral energy distribution of the Y0 dwarf WISE J035934.06−540154.6 consists of low-resolution (λ/Δλ ∼100) spectroscopy from 1–12 μm and three photometric points at 15, 18, and 21 μm. The spectrum exhibits numerous fundamental, overtone, and combination rotational–vibrational bands of H2O, CH4, CO, CO2, and NH3, including the previously unidentified ν 3 band of NH3 at 3 μm. Using a Rayleigh–Jeans tail to account for the flux emerging at wavelengths greater than 21 μm, we measure a bolometric luminosity of 1.523 ± 0.090 × 1020 W. We determine a semiempirical effective temperature estimate of 467−18+16 K using the bolometric luminosity and evolutionary models to estimate a radius. Finally, we compare the spectrum and photometry to a grid of atmospheric models and find reasonably good agreement with a model having T eff = 450 K, log g = 3.25 [cm s−2], and [M/H] = −0.3. However, the low surface gravity implies an extremely low mass of 1 M Jup and a very young age of 20 Myr, the latter of which is inconsistent with simulations of volume-limited samples of cool brown dwarfs.
我们首次获得了Y矮星的JWST光谱能量分布。Y0矮星WISE J035934.06−540154.6的光谱能量分布由1-12 μm的低分辨率(λ/Δλ ~ 100)光谱和15、18和21 μm的三个测光点组成。光谱显示了H2O、CH4、CO、CO2和NH3的许多基本、泛音和组合旋转振动带，包括之前未发现的NH3在3 μm的ν 3波段。使用瑞利-牛仔裤尾巴来解释波长大于21 μm的通量，我们测量到的放热光度为1.523±0.090 × 1020 W。我们确定了一个半经验有效温度估计467−18+16 K使用热光度和进化模型来估计半径。最后，我们将光谱和光度法与大气模型网格进行比较，发现与T = 450 K, log g = 3.25 [cm s - 2]和[M/H] = - 0.3的模型有相当好的一致性。然而，低表面重力意味着极低的质量(1 M Jup)和非常年轻的年龄(20 Myr)，后者与体积有限的冷褐矮星样本的模拟不一致。
{"title":"The First JWST Spectral Energy Distribution of a Y Dwarf","authors":"Samuel A Beiler, M. Cushing, D. Kirkpatrick, A. Schneider, S. Mukherjee, M. Marley","doi":"10.3847/2041-8213/ace32c","DOIUrl":"https://doi.org/10.3847/2041-8213/ace32c","url":null,"abstract":"We present the first JWST spectral energy distribution of a Y dwarf. This spectral energy distribution of the Y0 dwarf WISE J035934.06−540154.6 consists of low-resolution (λ/Δλ ∼100) spectroscopy from 1–12 μm and three photometric points at 15, 18, and 21 μm. The spectrum exhibits numerous fundamental, overtone, and combination rotational–vibrational bands of H2O, CH4, CO, CO2, and NH3, including the previously unidentified ν 3 band of NH3 at 3 μm. Using a Rayleigh–Jeans tail to account for the flux emerging at wavelengths greater than 21 μm, we measure a bolometric luminosity of 1.523 ± 0.090 × 1020 W. We determine a semiempirical effective temperature estimate of 467−18+16 K using the bolometric luminosity and evolutionary models to estimate a radius. Finally, we compare the spectrum and photometry to a grid of atmospheric models and find reasonably good agreement with a model having T eff = 450 K, log g = 3.25 [cm s−2], and [M/H] = −0.3. However, the low surface gravity implies an extremely low mass of 1 M Jup and a very young age of 20 Myr, the latter of which is inconsistent with simulations of volume-limited samples of cool brown dwarfs.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129411331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-20DOI: 10.3847/2041-8213/acdde4
P. Nazari, B. Tabone, M. L. R. van ’t Hoff, J. Jørgensen, E. V. van Dishoeck
Earth is deficient in carbon and nitrogen by up to ∼4 orders of magnitude compared with the Sun. Destruction of (carbon- and nitrogen-rich) refractory organics in the high-temperature planet-forming regions could explain this deficiency. Assuming a refractory cometary composition for these grains, their destruction enhances nitrogen-containing, oxygen-poor molecules in the hot gas (≳300 K) after the initial formation and sublimation of these molecules from oxygen-rich ices in the warm gas (∼150 K). Using observations of 37 high-mass protostars with the Atacama Large Millimeter/submillimeter Array, we find that oxygen-containing molecules (CH3OH and HNCO) systematically show no enhancement in their hot component. In contrast, nitrogen-containing, oxygen-poor molecules (CH3CN and C2H3CN) systematically show an enhancement of a factor ∼5 in their hot component, pointing to additional production of these molecules in the hot gas. Assuming only thermal excitation conditions, we interpret these results as a signature of destruction of refractory organics, consistent with the cometary composition. This destruction implies a higher C/O and N/O in the hot gas than the warm gas, while the exact values of these ratios depend on the fraction of grains that are effectively destroyed. This fraction can be found by future chemical models that constrain C/O and N/O from the abundances of minor carbon, nitrogen, and oxygen carriers presented here.
{"title":"Evidence for Ubiquitous Carbon Grain Destruction in Hot Protostellar Envelopes","authors":"P. Nazari, B. Tabone, M. L. R. van ’t Hoff, J. Jørgensen, E. V. van Dishoeck","doi":"10.3847/2041-8213/acdde4","DOIUrl":"https://doi.org/10.3847/2041-8213/acdde4","url":null,"abstract":"Earth is deficient in carbon and nitrogen by up to ∼4 orders of magnitude compared with the Sun. Destruction of (carbon- and nitrogen-rich) refractory organics in the high-temperature planet-forming regions could explain this deficiency. Assuming a refractory cometary composition for these grains, their destruction enhances nitrogen-containing, oxygen-poor molecules in the hot gas (≳300 K) after the initial formation and sublimation of these molecules from oxygen-rich ices in the warm gas (∼150 K). Using observations of 37 high-mass protostars with the Atacama Large Millimeter/submillimeter Array, we find that oxygen-containing molecules (CH3OH and HNCO) systematically show no enhancement in their hot component. In contrast, nitrogen-containing, oxygen-poor molecules (CH3CN and C2H3CN) systematically show an enhancement of a factor ∼5 in their hot component, pointing to additional production of these molecules in the hot gas. Assuming only thermal excitation conditions, we interpret these results as a signature of destruction of refractory organics, consistent with the cometary composition. This destruction implies a higher C/O and N/O in the hot gas than the warm gas, while the exact values of these ratios depend on the fraction of grains that are effectively destroyed. This fraction can be found by future chemical models that constrain C/O and N/O from the abundances of minor carbon, nitrogen, and oxygen carriers presented here.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128403571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-18DOI: 10.3847/2041-8213/acdf56
D. Banerjee, A. Evans, C. Woodward, S. Starrfield, K. Su, N. Ashok, R. Wagner
V445 Puppis, the only known Galactic helium nova, is a unique test bed to verify supernova (SN) theories in the single-degenerate channel that involve a white dwarf (WD) accreting matter from a helium-rich donor. An estimate of the mass of the helium shell on the WD is crucial to deciding whether or not it will undergo an SN detonation. In this context, this study estimates the dust and ejecta masses in the 2000 November eruption of V445 Pup. Subsequent to its outburst, the star became cocooned in a dust envelope. An analysis of the spectral energy distribution (SED) of the dust using infrared data shows that V445 Pup produced at least 10−3 M ⊙ of dust, which is unprecedented for a classical or recurrent nova. The SED can be explained by a combination of a cold dust component at 105 ± 10 K, mass (1.9 ± 0.8) × 10−3 M ⊙, and a warm dust component at 255 ± 10 K, mass (2.2 ± 1.2) × 10−5 M ⊙. For a conservative choice of the gas-to-dust mass ratio in the range 10–100, the mass of the ejecta is 0.01–0.1 M ⊙. Such a high mass range raises the question: why did V445 Pup not detonate as a Type Ia SN as is predicted in certain double-detonation sub-Chandrasekhar supernovae formalisms? We reexamine the nature of V445 Pup and discuss its role as a potential SN progenitor.
{"title":"V445 Puppis: Dustier than a Thousand Novae","authors":"D. Banerjee, A. Evans, C. Woodward, S. Starrfield, K. Su, N. Ashok, R. Wagner","doi":"10.3847/2041-8213/acdf56","DOIUrl":"https://doi.org/10.3847/2041-8213/acdf56","url":null,"abstract":"V445 Puppis, the only known Galactic helium nova, is a unique test bed to verify supernova (SN) theories in the single-degenerate channel that involve a white dwarf (WD) accreting matter from a helium-rich donor. An estimate of the mass of the helium shell on the WD is crucial to deciding whether or not it will undergo an SN detonation. In this context, this study estimates the dust and ejecta masses in the 2000 November eruption of V445 Pup. Subsequent to its outburst, the star became cocooned in a dust envelope. An analysis of the spectral energy distribution (SED) of the dust using infrared data shows that V445 Pup produced at least 10−3 M ⊙ of dust, which is unprecedented for a classical or recurrent nova. The SED can be explained by a combination of a cold dust component at 105 ± 10 K, mass (1.9 ± 0.8) × 10−3 M ⊙, and a warm dust component at 255 ± 10 K, mass (2.2 ± 1.2) × 10−5 M ⊙. For a conservative choice of the gas-to-dust mass ratio in the range 10–100, the mass of the ejecta is 0.01–0.1 M ⊙. Such a high mass range raises the question: why did V445 Pup not detonate as a Type Ia SN as is predicted in certain double-detonation sub-Chandrasekhar supernovae formalisms? We reexamine the nature of V445 Pup and discuss its role as a potential SN progenitor.","PeriodicalId":179976,"journal":{"name":"The Astrophysical Journal Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127920550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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