Gravity Grinch
@gravitygrinch.bsky.social
observational cosmologist -- the particle horizon is the limit!
https://thegravitygrinch.blogspot.com
https://thegravitygrinch.blogspot.com
Pinned
Paper day for least-model-dependent astrophysics! On today's menu: an old-new mathem. robust galaxy clustering, a clever way to reduce large distance-uncertainties from non-redshift probes & our favourite friendly neighbouring cluster, Coma! 🧶🧶
arxiv.org/abs/2504.04135
#cosmology #astronomy
arxiv.org/abs/2504.04135
#cosmology #astronomy
At least something positive in these troublesome times: I am now a member of the advisory board for the Giordano Bruno Foundation in Germany:
www.giordano-bruno-stiftung.de/en/content/w...
#astronomy #humanism #scicomm
www.giordano-bruno-stiftung.de/en/content/w...
#astronomy #humanism #scicomm
Wagner, Jenny
Dr. Jenny Wagner, Astrophysicist
www.giordano-bruno-stiftung.de
June 18, 2025 at 6:08 AM
At least something positive in these troublesome times: I am now a member of the advisory board for the Giordano Bruno Foundation in Germany:
www.giordano-bruno-stiftung.de/en/content/w...
#astronomy #humanism #scicomm
www.giordano-bruno-stiftung.de/en/content/w...
#astronomy #humanism #scicomm
Happy to announce that my paper on galaxy infall models together with David Benisty is now published in Astronomy & Astrophysics, thanks a lot to the journal for the great processing!
doi.org/10.1051/0004...
#GalaxyKinematics #astronomy #astrophysics #AstrophysicsOfGalaxies
doi.org/10.1051/0004...
#GalaxyKinematics #astronomy #astrophysics #AstrophysicsOfGalaxies
June 17, 2025 at 9:44 AM
Happy to announce that my paper on galaxy infall models together with David Benisty is now published in Astronomy & Astrophysics, thanks a lot to the journal for the great processing!
doi.org/10.1051/0004...
#GalaxyKinematics #astronomy #astrophysics #AstrophysicsOfGalaxies
doi.org/10.1051/0004...
#GalaxyKinematics #astronomy #astrophysics #AstrophysicsOfGalaxies
Reposted by Gravity Grinch
Here is my next YouTube short about the great discovery by David Benisty et al. that the cosmological constant can be inferred from the Milky Way and Andromeda system! This is so important because it's a complementary probe to the CMB.
youtube.com/shorts/mwF0H...
#astronomy #scicomm #YouTube
youtube.com/shorts/mwF0H...
#astronomy #scicomm #YouTube
Kosmologische Konstante • Messbar in unserer Galaxiengruppe? | Jenny Wagner
YouTube video by Urknall, Weltall und das Leben
youtube.com
June 12, 2025 at 10:33 AM
Here is my next YouTube short about the great discovery by David Benisty et al. that the cosmological constant can be inferred from the Milky Way and Andromeda system! This is so important because it's a complementary probe to the CMB.
youtube.com/shorts/mwF0H...
#astronomy #scicomm #YouTube
youtube.com/shorts/mwF0H...
#astronomy #scicomm #YouTube
Here is my next YouTube short about the great discovery by David Benisty et al. that the cosmological constant can be inferred from the Milky Way and Andromeda system! This is so important because it's a complementary probe to the CMB.
youtube.com/shorts/mwF0H...
#astronomy #scicomm #YouTube
youtube.com/shorts/mwF0H...
#astronomy #scicomm #YouTube
Kosmologische Konstante • Messbar in unserer Galaxiengruppe? | Jenny Wagner
YouTube video by Urknall, Weltall und das Leben
youtube.com
June 12, 2025 at 10:33 AM
Here is my next YouTube short about the great discovery by David Benisty et al. that the cosmological constant can be inferred from the Milky Way and Andromeda system! This is so important because it's a complementary probe to the CMB.
youtube.com/shorts/mwF0H...
#astronomy #scicomm #YouTube
youtube.com/shorts/mwF0H...
#astronomy #scicomm #YouTube
I asked ChatGPT, Claude, Grok, and deepseek to flip a png that contained text and then flip the text to be readable again. Deepseek can't handle images, Claude did sth crazy & useless output, Grok similarly, Chat just flipped the image but not the text.
Can this be done? How?
#Chatgpt
Can this be done? How?
#Chatgpt
June 11, 2025 at 8:51 PM
I asked ChatGPT, Claude, Grok, and deepseek to flip a png that contained text and then flip the text to be readable again. Deepseek can't handle images, Claude did sth crazy & useless output, Grok similarly, Chat just flipped the image but not the text.
Can this be done? How?
#Chatgpt
Can this be done? How?
#Chatgpt
Good and bad news: my first #YouTube short was released today: youtube.com/shorts/410Fg...
good: I have more ideas what to do.
bad: the AI-translation really s****. Anybody got an idea how to improve that? Doing it in English from the start sounds the most reasonable for me....
#SciComm #Astronomy
good: I have more ideas what to do.
bad: the AI-translation really s****. Anybody got an idea how to improve that? Doing it in English from the start sounds the most reasonable for me....
#SciComm #Astronomy
Licht, Gravitation & Einstein • Wie Masse Licht krümmt | Jenny Wagner
YouTube video by Urknall, Weltall und das Leben
youtube.com
May 28, 2025 at 8:22 PM
Good and bad news: my first #YouTube short was released today: youtube.com/shorts/410Fg...
good: I have more ideas what to do.
bad: the AI-translation really s****. Anybody got an idea how to improve that? Doing it in English from the start sounds the most reasonable for me....
#SciComm #Astronomy
good: I have more ideas what to do.
bad: the AI-translation really s****. Anybody got an idea how to improve that? Doing it in English from the start sounds the most reasonable for me....
#SciComm #Astronomy
Reposted by Gravity Grinch
Happy 91th birthday to #RoyKerr -- the man who made a #BlackHole spin and who assured me that his cat is safe from any thought experiments related to his research! 🥂
(Picture by his lovely wife taken from the bird platform...)
#astronomy #astrophysics #cosmology
(Picture by his lovely wife taken from the bird platform...)
#astronomy #astrophysics #cosmology
May 15, 2025 at 10:04 PM
Happy 91th birthday to #RoyKerr -- the man who made a #BlackHole spin and who assured me that his cat is safe from any thought experiments related to his research! 🥂
(Picture by his lovely wife taken from the bird platform...)
#astronomy #astrophysics #cosmology
(Picture by his lovely wife taken from the bird platform...)
#astronomy #astrophysics #cosmology
Happy 91th birthday to #RoyKerr -- the man who made a #BlackHole spin and who assured me that his cat is safe from any thought experiments related to his research! 🥂
(Picture by his lovely wife taken from the bird platform...)
#astronomy #astrophysics #cosmology
(Picture by his lovely wife taken from the bird platform...)
#astronomy #astrophysics #cosmology
May 15, 2025 at 10:04 PM
Happy 91th birthday to #RoyKerr -- the man who made a #BlackHole spin and who assured me that his cat is safe from any thought experiments related to his research! 🥂
(Picture by his lovely wife taken from the bird platform...)
#astronomy #astrophysics #cosmology
(Picture by his lovely wife taken from the bird platform...)
#astronomy #astrophysics #cosmology
...and if you want to know more about the motions of the galaxies around M81 and M82 and what we know about relative velocities between pairs, groups, and galaxy clusters, check out our new paper on relative kinematics:
arxiv.org/abs/2501.13149
#astronomy #astrophysics #GalaxyKinematics
arxiv.org/abs/2501.13149
#astronomy #astrophysics #GalaxyKinematics
May 13, 2025 at 9:04 AM
...and if you want to know more about the motions of the galaxies around M81 and M82 and what we know about relative velocities between pairs, groups, and galaxy clusters, check out our new paper on relative kinematics:
arxiv.org/abs/2501.13149
#astronomy #astrophysics #GalaxyKinematics
arxiv.org/abs/2501.13149
#astronomy #astrophysics #GalaxyKinematics
Black Hole Week might be over, but today's arxiv had an interesting paper on a dwarf galaxy where a black hole provided enough mass to explain the observables and a dark-matter halo fit seems disfavoured: arxiv.org/abs/2505.06198
#BlackHole #astronomy #astrophysics #DarkMatter
#BlackHole #astronomy #astrophysics #DarkMatter
The "Dark-Matter Dominated" Galaxy Segue 1 Modeled with a Black Hole and no Dark Halo
The dwarf spheroidal galaxy, Segue 1, is thought to have one of the largest ratios of dark matter to stellar mass. Using orbit-based dynamical models, we model Segue 1, including a dark halo and a cen...
arxiv.org
May 12, 2025 at 4:16 PM
Black Hole Week might be over, but today's arxiv had an interesting paper on a dwarf galaxy where a black hole provided enough mass to explain the observables and a dark-matter halo fit seems disfavoured: arxiv.org/abs/2505.06198
#BlackHole #astronomy #astrophysics #DarkMatter
#BlackHole #astronomy #astrophysics #DarkMatter
Reposted by Gravity Grinch
Question of the day: does someone know a (recent) catalogue of galaxy groups & clusters in our local universe with redshift-independent distances, redshifts and member galaxy properties like vel-disps? (we know Cosmicflows we are rather thinking of DESI or so)
#astronomy #LocalUniverse #DarkMatter
#astronomy #LocalUniverse #DarkMatter
May 5, 2025 at 4:58 PM
Question of the day: does someone know a (recent) catalogue of galaxy groups & clusters in our local universe with redshift-independent distances, redshifts and member galaxy properties like vel-disps? (we know Cosmicflows we are rather thinking of DESI or so)
#astronomy #LocalUniverse #DarkMatter
#astronomy #LocalUniverse #DarkMatter
Question of the day: does someone know a (recent) catalogue of galaxy groups & clusters in our local universe with redshift-independent distances, redshifts and member galaxy properties like vel-disps? (we know Cosmicflows we are rather thinking of DESI or so)
#astronomy #LocalUniverse #DarkMatter
#astronomy #LocalUniverse #DarkMatter
May 5, 2025 at 4:58 PM
Question of the day: does someone know a (recent) catalogue of galaxy groups & clusters in our local universe with redshift-independent distances, redshifts and member galaxy properties like vel-disps? (we know Cosmicflows we are rather thinking of DESI or so)
#astronomy #LocalUniverse #DarkMatter
#astronomy #LocalUniverse #DarkMatter
Very interesting stuff out there on the arxiv today! And still a Nick-Kaiser legacy paper!! Wow!
arxiv.org/abs/2504.19922
#astronomy #cosmology #GalaxyClusters
arxiv.org/abs/2504.19922
#astronomy #cosmology #GalaxyClusters
Dynamical analysis of stacked samples of asymmetric, non-static, self-gravitating systems
We use numerical simulations to explore biases that arise in dynamical estimates of the mean mass profile for a collection of galaxy clusters that have been stacked to make a composite. There are thre...
arxiv.org
April 29, 2025 at 7:02 PM
Very interesting stuff out there on the arxiv today! And still a Nick-Kaiser legacy paper!! Wow!
arxiv.org/abs/2504.19922
#astronomy #cosmology #GalaxyClusters
arxiv.org/abs/2504.19922
#astronomy #cosmology #GalaxyClusters
Fresh from the arxiv:
arxiv.org/abs/2504.16991
check this interesting paper out which is a follow-up application to my previous paper with the first author. They now look at the impact of missing velocity components on the mass estimate of our Local Group.
#astronomy #NearFieldCosmology
arxiv.org/abs/2504.16991
check this interesting paper out which is a follow-up application to my previous paper with the first author. They now look at the impact of missing velocity components on the mass estimate of our Local Group.
#astronomy #NearFieldCosmology
Line-of-Sight Velocity Projection Impact on the Local Group Mass
The mass of the Local Group (LG), comprising the Milky Way (MW), Andromeda (M31), and their satellites, is crucial for validating galaxy formation and cosmological models. Traditional virial mass esti...
arxiv.org
April 25, 2025 at 1:48 PM
Fresh from the arxiv:
arxiv.org/abs/2504.16991
check this interesting paper out which is a follow-up application to my previous paper with the first author. They now look at the impact of missing velocity components on the mass estimate of our Local Group.
#astronomy #NearFieldCosmology
arxiv.org/abs/2504.16991
check this interesting paper out which is a follow-up application to my previous paper with the first author. They now look at the impact of missing velocity components on the mass estimate of our Local Group.
#astronomy #NearFieldCosmology
Reposted by Gravity Grinch
#AAS246 LAST CALL FOR LATE ABSTRACTS! To share your latest research with an eager audience of scientists at all career stages, submit your late abstract (for iPosters only) in one of more than 50 topical categories by 11:59 pm ET on Friday, 25 April. aas.org/meetings/aas...
April 22, 2025 at 2:01 PM
#AAS246 LAST CALL FOR LATE ABSTRACTS! To share your latest research with an eager audience of scientists at all career stages, submit your late abstract (for iPosters only) in one of more than 50 topical categories by 11:59 pm ET on Friday, 25 April. aas.org/meetings/aas...
Happy Earth Day to everyone and have a try writing your name or anything you like in earthly letters!
landsat.gsfc.nasa.gov/apps/YourNam...
landsat.gsfc.nasa.gov/apps/YourNam...
April 22, 2025 at 3:09 PM
Happy Earth Day to everyone and have a try writing your name or anything you like in earthly letters!
landsat.gsfc.nasa.gov/apps/YourNam...
landsat.gsfc.nasa.gov/apps/YourNam...
Potentially new life found on other planets, but one special life lost on this planet this week: www.princeton.edu/news/2025/04...
#JerryOstriker #Physicists #astrophysics #cosmology #DarkMatter
#JerryOstriker #Physicists #astrophysics #cosmology #DarkMatter
Astrophysicist Jeremiah P. Ostriker, pioneer of modern cosmology and ‘source of inspiration,’ dies at 87
Ostriker is responsible for groundbreaking discoveries that forever changed the way astronomers think about what the universe is made of, including the existence of dark matter.
www.princeton.edu
April 17, 2025 at 10:15 AM
Potentially new life found on other planets, but one special life lost on this planet this week: www.princeton.edu/news/2025/04...
#JerryOstriker #Physicists #astrophysics #cosmology #DarkMatter
#JerryOstriker #Physicists #astrophysics #cosmology #DarkMatter
Fresh from the arxiv: calc. (numerically) the impact of a wave hitting a spherical overdensity in the cosmos, the wave suffers from a Shapiro delay and thus shows interference patterns. So do we really need fuzzy dark matter to observe interference?! arxiv.org/abs/2504.08286
#astronomy #DarkMatter
#astronomy #DarkMatter
Numerical evolution of Maxwell's equations for wavefronts propagating through a spherical gravitational potential
We present a scheme for numerically solving Maxwell's equations in a weakly perturbed spacetime without introducing the usual geometric optics approximation. Using this scheme, we study light propagat...
arxiv.org
April 14, 2025 at 8:50 AM
Fresh from the arxiv: calc. (numerically) the impact of a wave hitting a spherical overdensity in the cosmos, the wave suffers from a Shapiro delay and thus shows interference patterns. So do we really need fuzzy dark matter to observe interference?! arxiv.org/abs/2504.08286
#astronomy #DarkMatter
#astronomy #DarkMatter
Wow! Welcome to my new followers! 🤩
Now that we are friends, I will think of a paper worth submitting (never tried).
Now that we are friends, I will think of a paper worth submitting (never tried).
April 11, 2025 at 7:15 PM
Wow! Welcome to my new followers! 🤩
Now that we are friends, I will think of a paper worth submitting (never tried).
Now that we are friends, I will think of a paper worth submitting (never tried).
Reposted by Gravity Grinch
Paper day again! Have a look at our findings on galaxy infall models, first time checked with simulations (up to our knowledge):
arxiv.org/abs/2501.13149
Thread about the main results below. Endure the equations, stay for the final punch on clusters! 🧶
#astronomy #cosmology #GalaxyKinematics
arxiv.org/abs/2501.13149
Thread about the main results below. Endure the equations, stay for the final punch on clusters! 🧶
#astronomy #cosmology #GalaxyKinematics
Galaxy infall models for arbitrary velocity directions
For most galaxies in the cosmos, our knowledge of their motion is limited to line-of-sight velocities from redshift observations. To determine the radial velocity between two galaxies the minor and ma...
arxiv.org
April 10, 2025 at 9:14 PM
Paper day again! Have a look at our findings on galaxy infall models, first time checked with simulations (up to our knowledge):
arxiv.org/abs/2501.13149
Thread about the main results below. Endure the equations, stay for the final punch on clusters! 🧶
#astronomy #cosmology #GalaxyKinematics
arxiv.org/abs/2501.13149
Thread about the main results below. Endure the equations, stay for the final punch on clusters! 🧶
#astronomy #cosmology #GalaxyKinematics
Paper day again! Have a look at our findings on galaxy infall models, first time checked with simulations (up to our knowledge):
arxiv.org/abs/2501.13149
Thread about the main results below. Endure the equations, stay for the final punch on clusters! 🧶
#astronomy #cosmology #GalaxyKinematics
arxiv.org/abs/2501.13149
Thread about the main results below. Endure the equations, stay for the final punch on clusters! 🧶
#astronomy #cosmology #GalaxyKinematics
Galaxy infall models for arbitrary velocity directions
For most galaxies in the cosmos, our knowledge of their motion is limited to line-of-sight velocities from redshift observations. To determine the radial velocity between two galaxies the minor and ma...
arxiv.org
April 10, 2025 at 9:14 PM
Paper day again! Have a look at our findings on galaxy infall models, first time checked with simulations (up to our knowledge):
arxiv.org/abs/2501.13149
Thread about the main results below. Endure the equations, stay for the final punch on clusters! 🧶
#astronomy #cosmology #GalaxyKinematics
arxiv.org/abs/2501.13149
Thread about the main results below. Endure the equations, stay for the final punch on clusters! 🧶
#astronomy #cosmology #GalaxyKinematics
Reposted by Gravity Grinch
Paper day for least-model-dependent astrophysics! On today's menu: an old-new mathem. robust galaxy clustering, a clever way to reduce large distance-uncertainties from non-redshift probes & our favourite friendly neighbouring cluster, Coma! 🧶🧶
arxiv.org/abs/2504.04135
#cosmology #astronomy
arxiv.org/abs/2504.04135
#cosmology #astronomy
April 8, 2025 at 5:41 PM
Paper day for least-model-dependent astrophysics! On today's menu: an old-new mathem. robust galaxy clustering, a clever way to reduce large distance-uncertainties from non-redshift probes & our favourite friendly neighbouring cluster, Coma! 🧶🧶
arxiv.org/abs/2504.04135
#cosmology #astronomy
arxiv.org/abs/2504.04135
#cosmology #astronomy
Paper day for least-model-dependent astrophysics! On today's menu: an old-new mathem. robust galaxy clustering, a clever way to reduce large distance-uncertainties from non-redshift probes & our favourite friendly neighbouring cluster, Coma! 🧶🧶
arxiv.org/abs/2504.04135
#cosmology #astronomy
arxiv.org/abs/2504.04135
#cosmology #astronomy
April 8, 2025 at 5:41 PM
Paper day for least-model-dependent astrophysics! On today's menu: an old-new mathem. robust galaxy clustering, a clever way to reduce large distance-uncertainties from non-redshift probes & our favourite friendly neighbouring cluster, Coma! 🧶🧶
arxiv.org/abs/2504.04135
#cosmology #astronomy
arxiv.org/abs/2504.04135
#cosmology #astronomy
An interesting strong lensing discovery by @NASAWebb : arxiv.org/abs/2504.03571
"if a bottom-heavy IMF for elliptical gals is employed, stellar mass estimations increase and can account for the majority of the lensing mass (up to ∼83\%), reducing the need for dark matter"!
#DarkMatter #Cosmology
"if a bottom-heavy IMF for elliptical gals is employed, stellar mass estimations increase and can account for the majority of the lensing mass (up to ∼83\%), reducing the need for dark matter"!
#DarkMatter #Cosmology
JWSTs PEARLS: NIRCam imaging and NIRISS spectroscopy of a $z=3.6$ star-forming galaxy lensed into a near-Einstein Ring by a $z=1.258$ massive elliptical galaxy
We present the discovery, and initial lensing analysis, of a high-redshift galaxy-galaxy lensing system within the JWST-PEARLS/HST-TREASUREHUNT North Ecliptic Pole Time Domain Field (designated NEPJ17...
arxiv.org
April 7, 2025 at 3:25 PM
An interesting strong lensing discovery by @NASAWebb : arxiv.org/abs/2504.03571
"if a bottom-heavy IMF for elliptical gals is employed, stellar mass estimations increase and can account for the majority of the lensing mass (up to ∼83\%), reducing the need for dark matter"!
#DarkMatter #Cosmology
"if a bottom-heavy IMF for elliptical gals is employed, stellar mass estimations increase and can account for the majority of the lensing mass (up to ∼83\%), reducing the need for dark matter"!
#DarkMatter #Cosmology
New review on tensions in #cosmology: arxiv.org/abs/2504.01669
As a collaborator said: 500+ authors wrote 400+ pages on the issues with our cosmo model. Can we still claim #LCDM is fine?!
I contributed bc the sum of all issues should make us rethink the 100-yo model.
#astrophysics #astronomy
As a collaborator said: 500+ authors wrote 400+ pages on the issues with our cosmo model. Can we still claim #LCDM is fine?!
I contributed bc the sum of all issues should make us rethink the 100-yo model.
#astrophysics #astronomy
The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
The standard model of cosmology has provided a good phenomenological description of a wide range of observations both at astrophysical and cosmological scales for several decades. This concordance mod...
arxiv.org
April 3, 2025 at 12:33 PM
New review on tensions in #cosmology: arxiv.org/abs/2504.01669
As a collaborator said: 500+ authors wrote 400+ pages on the issues with our cosmo model. Can we still claim #LCDM is fine?!
I contributed bc the sum of all issues should make us rethink the 100-yo model.
#astrophysics #astronomy
As a collaborator said: 500+ authors wrote 400+ pages on the issues with our cosmo model. Can we still claim #LCDM is fine?!
I contributed bc the sum of all issues should make us rethink the 100-yo model.
#astrophysics #astronomy